Raspberry Pi Mechatronics Projects HOTSHOT 1849696225 %7BE56CA9D0%7D %5BYamanoor %26 Yamanoor 2015 01 26%5D {E56CA9D0} [Yamanoor & 26]

User Manual: 1849696225 %7BE56CA9D0%7D Raspberry Pi Mechatronics Projects Hotshot %5BYamanoor %26 Yamanoor 2015-01-26%5D

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RaspberryPiMechatronicsProjects
HOTSHOT
TableofContents
RaspberryPiMechatronicsProjectsHOTSHOT
Credits
AbouttheAuthors
AbouttheReviewers
www.PacktPub.com
Supportfiles,eBooks,discountoffers,andmore
Whysubscribe?
FreeaccessforPacktaccountholders
Preface
Whatthisbookcovers
Whatyouneedforthisbook
Whothisbookisfor
Conventions
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
Missionchecklist
Task1
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Classifiedintel
Readerfeedback
Customersupport
Downloadingtheexamplecode
Downloadingthecolorimagesofthisbook
Errata
Piracy
Questions
1.HelloWorld
AquickintroductiontotheRaspberryPi
FeaturesofaRaspberryPi
WherecanIbuyaRaspberryPi?
RequirementstogetstartedwiththeRaspberryPi
OperatingsystemsontheRaspberryPi
GettingstartedwithRaspbian
DownloadingRaspbian
FlashingimageontotheSDcard
Windows
Linux
Acommand-lineinterface-basedapproach
IdentifyingtheSDcardmountpoint
UnmounttheSDcard
FlashtheSDcard
GUI-basedapproach
SettinguptheRaspberryPi
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
Missionchecklist
Huntingandgathering
Engagethrusters
Objectivecomplete–minidebriefing
SettinguptheGPIO
Engagethrusters
InstallingGPIOlibraries
Objectivecomplete–minidebriefing
GPIOprogrammingusingPython
Engagethrusters
Analternativetoquick2wire–RPi.GPIO
Objectivecomplete–minidebriefing
Electricaloutputofourprogram
Engagethrusters
Objectivecomplete–minidebriefing
IntroductiontothePiCrust–aprototypingplatformfortheRaspberryPi
Missionaccomplished
Hotshotchallenge
2.ARaspberryWebIDEExample
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
Missionchecklist
Installation,features,andusageoftheOccidentalisoperatingsystemfromAdafruit
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
SetupofaremoteloginintotheRaspberryPi
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
InstallationoftheRaspberryPiWebIDE
Engagethrusters
Objectivecomplete–minidebriefing
PythondevelopmentontheWebIDE
Prepareforliftoff
QuickintroductiontotheI2Cinterface
ConfiguringtheI2CinterfaceontheRaspberryPi
Engagethrusters
Objectivecomplete–minidebriefing
TestanddebuggingexamplesusingtheWebIDE
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
3.TheArduinoRaspberryPiInterface
Missionbriefing
Whyisitawesome?
WherecanyoubuyanArduino?
YourHotshotobjectives
Missionchecklist
InstallingtheArduinoIDE
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
ProgrammingtheArduinousingtheRaspberryPi
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
RaspberryPiAlaMode
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
TheWeasleyweatherclock
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
ControllingthestepperusingtheArduino
Prepareforliftoff
Engagethrusters
Counterclockwiserotationofthesteppermotor
Objectivecomplete–minidebriefing
ControllingtheRGBLEDStripusingtheArduino
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
I2CCommunicationusingtheArduino(optional)
Prepareforliftoff
Engagethrusters
The7-Segmentdisplay
8x8LEDmatrix
BlinkM
Proximitysensor
Objectivecomplete–minidebriefing
SerialportcommunicationwiththeRaspberryPi
Engagethrusters
PythonprogramfortheWeasleyclock
Arduinoacknowledgementtocontrolsignal
Controlflowfortheweatherclock
Temperaturedata
ControloftheRGBLEDstrip
Controlofstepperviaserialport
Programmingtheweatherforecastposition
8x8matrixcontrol
BlinkMcontrol
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
4.ChristmasLightSequencer
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
InterfacethedevicestotheRaspberryPi
Prepareforliftoff
Engagethrusters
ConnectingmultipleappliancestotheRaspberryPi
Objectivecomplete–minidebriefing
SettingupthedigitallyaddressableRGBmatrix
Prepareforliftoff
WherecanIbuythem?
Engagethrusters
Howdoesitwork?
LightinguptheRGBLEDstrip
AnArduino-basedcontrol
Objectivecomplete–minidebriefing
Interfaceofanaudiodevice
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Installingthewebserver
Prepareforliftoff
Engagethrusters
Objectivecomplete–missiondebriefing
Interfacingthewebserver
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
References
5.InternetofThingsExample–AnE-mailAlertWaterFountain
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
InstallationoftheFlaskframework
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
ControllingRGBLEDsfromawebpage
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Setupofthee-mailalertsinthefountain
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
6.RaspberryPiasaPersonalAssistant
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
Settingupthee-mailfeedparser
Prepareforliftoff
Engagethrusters
Settinguptheparserforremindersandevents
Prepareforliftoff
Engagethrusters
Designinganenclosuredesignforthepersonalassistant
Prepareforliftoff
Engagethrusters
Settinguptheassemblyforthedishmonitor
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Settingupsensorsforthekeyalertsystem
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenges
References
7.RaspberryPi-basedLineFollowingRobot
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
Missionchecklist
AssemblyofthePiPlateforthelinefollowingrobot
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Sensorselection,interface,anddatainterpretation
Engagethrusters
LightDependentResistors
Infraredemitter/detector
Machine-vision-basedlinefollowingrobot
Sensorselection
Objectivecomplete–missiondebriefing
Implementationoflinefollowinglogicbasedonsensordata
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Testingthemotordrivercircuit
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Preparationofthelinefollowingcourse
Prepareforliftoff
Engagethrusters
Useelectricaltapeandbuildatrack
Designingthechassisforthelinefollowingrobot
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Astep-by-stepassemblyoftherobot
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
References
8.ConnectFourDesktopGameusingRaspberryPi
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
Helloworldexamplewiththepygame
Prepareforliftoff
Engagethrusters
Playingsoundsusingthepygamemodule
Buildingmenususingthepygamemodule
Objectivecomplete–minidebriefing
GettingstartedwiththeConnectFourgame(UIandsoundeffects)
Prepareforliftoff
EngageThrusters
Addingamenuforthegame
Addingsoundstothegame
Objectivecomplete–missiondebriefing
InterfacinggameinputsusingthePiFacemodule
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
AbriefdescriptionoftheConnectFourGameAI
Prepareforliftoff
Engagethrusters
Maingameloop
Objectivecomplete–minidebriefing
Marqueedesignandcontrol(optional)
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Setupoftheswitchesusingacardboardbox
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
References
9.TheRaspberryPi-enabledPet/WildlifeMonitor
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
Installingandtestingthepython-twistedframework
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
SettingupandtestingSparkCoretointeractwithappliances
Prepareforliftoff
EngageThrusters
Objectivecomplete–minidebriefing
InstallingandtestingtheGoogleCoderprojectontheRaspberryPi
Prepareforliftoff
Engagethrusters
Objectivecomplete–objectivecomplete
Abriefoverviewofabirdfeederthattriggersacamera
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Alternativesandprojectideastoconsider
Missionaccomplished
Hotshotchallenge
10.RaspberryPiPersonalHealthMonitor
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
Missionchecklist
Settingupawebservertorecordhealthparameters
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
AsimpleexercisetoolusingtheRaspberryPi
Prepareforliftoff
Engagethrusters
Aminiprojectidea
Objectivecomplete–minidebriefing
Settingupane-mailfeedparsertorefillaprescriptionaswellasremindtheuserabout
anupcomingdoctor’sappointment
Engagethrusters
Settingupareminderfordoctor’sappointments
Objectivecomplete–minidebriefing
Asimpletoolthatremindsapersontotakehis/herpills
Prepareforliftoff
Engagethrusters
Otherprojectideas
Objectivecomplete–minidebriefing
Missionaccomplished
Hotshotchallenge
11.HomeAutomationusingRaspberryPi
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
Asimpleexamplethatcontrolslimitedindoorandoutdoorlightingintheevening
Prepareforliftoff
Softwareprerequisites
Engagethrusters
Objectivecomplete–minidebriefing
Alternativesolutionsandsomeprojectideastoconsider
Acustomarywebserverexample
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
Turningonalawnsprinkleronlywhenthereisnorainforecast!
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
GainingremoteaccesstoyourRaspberryPitocontrolappliances
Someprojectideastoconsider
Missionaccomplished
12.UsingaRaspberryPiforScienceandEducation
Missionbriefing
Whyisitawesome?
YourHotshotobjectives
ImprovingyourvocabularyusingtheRaspberryPi
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
RaspberryPiandKhanAcademy
Someideastoconsider
BuildingasciencefairexhibitusingtheRaspberryPi
Prepareforliftoff
Engagethrusters
Objectivecomplete–minidebriefing
SomesimpleeducationalexperimentsusingtheRaspberryPi
Hotshotchallenge
13.TipsandTricks
Missionbriefing
Whyisitawesome?
Yourobjectives
Missionchecklist
SettingupRaspberryPiasadevelopmentplatform
#1–SimpletrickforPythondevelopmentviaremotelogin
#2WebdevelopmentusingGoogleCoder
#3AdafruitOccidentalis
#4JavaDevelopmentusingtheRaspberryPi
#5TheThingboxproject
RemotelyloggingintheRaspberryPifromanywhereontheInternet
ProblemsthatmightbeencounteredwhileusingRaspberryPi
SDcardcorruption
Powerissues
DevicespoweredbyUSB
Cooladd-onhardwaresourcesdevelopedfortheRaspberryPiplatform
TheRaspberryPimodelBversusB+,modelAversusA+
Projectideasthatcanbeimplementedoveraweekend
UsefulresourcesfortheRaspberryPi
RaspberryPiFoundation’sforums:
RaspberryPiStackExchange:
Element14’sRaspberryPicommunity:
Missionaccomplished
Index
RaspberryPiMechatronicsProjects
HOTSHOT
RaspberryPiMechatronicsProjects
HOTSHOT
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Firstpublished:February2015
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Credits
Authors
SaiYamanoor
SrihariYamanoor
Reviewers
GuyScheffer
SreedharVaddi
CheukYu
CommissioningEditor
UshaIyer
AcquisitionEditors
UshaIyer
RebeccaPedley
SamWood
ContentDevelopmentEditor
SusmitaSabot
TechnicalEditor
ParagTopre
CopyEditor
JanbalDharmaraj
ProjectCoordinator
MiltonD’souza
Proofreaders
SimranBhogal
MariaGould
AmeeshaGreen
PaulHindle
Indexer
HemanginiBari
Graphics
SheetalAute
DishaHaria
ProductionCoordinators
AparnaBhagat
ManuJoseph
CoverWork
AparnaBhagat
AbouttheAuthors
SaiYamanoorisamechatronicsengineerworkingforaprivatestart-upschoolintheSan
FranciscoBayAreawherehebuildsdevicesthathelpstudentsachievetheirfullpotential.
HecompletedhisdegreeinmechanicalengineeringatCarnegieMellonUniversity,
Pittsburgh,PA,andhisundergraduateworkinmechatronicsatSriKrishnaCollegeof
EngineeringandTechnology,Coimbatore,India.Hisinterests,deeplyrootedinDIYand
opensoftwareandhardwarecultures,includedevelopinggadgetsandappsthatimprove
qualityoflife,InternetofThings,crowdfunding,education,andnewtechnologies.Inhis
sparetime,heplayswithvariousdevicesandarchitecturessuchasRaspberryPi,Arduino,
Galileo,Androiddevices,andothers.Saishareshisadventureswithmechatronicsatthe
aptlynamed“MechatronicsCraze”blogathttp://mechatronicscraze.wordpress.com/.
Iwanttothankmyparentsforencouragingmeinallmyendeavorsandformakingme
whatIamtoday.Iamgratefultomybrotherwhohashelpedshapemycareerallthese
years.IlookforwardtoworkingwithSriharionsimilarprojectsinthefuture.Isincerely
thankMr.S.BalajiRaghavendrawhohasbeenagreatsourceofinspirationtomewhile
pursuingmyundergraduatedegree.IamalsothankfultoSusmitaSabotandtheentire
supportteamatPacktPublishingwhowerepatientandunderstoodthecircumstances
duringdifficulttimes.
SrihariYamanoorisanaturephotographerandmechanicalengineerwithexperience
workinginmedicaldevicedesignandCAD/CAM.Hecompletedhismaster’sinscience
aswellasadegreeinengineeringfromStanfordUniversity.Hisworkandinterestsin
medicaldevicesincludewomen’shealth,cancer,orthopedics,andcardiovasculardiseases,
aswellasnewerareassuchasdigitalhealthandelectronichealthrecords.Hehasseveral
thousandsofhoursofCADexperiencebehindhimandisalsocertifiedamongother
thingsasaSolidWorksexpert,simulationprofessional,andaSolidWorksinstructor.His
interestsrangefromengineeringandeducationtosocialentrepreneurship,animalwelfare,
andcrowdfunding.
Iwouldliketothankmyparents,NarasimhanandYasodaVenakatakrishnan,fortheir
steadfastsupportinmyeducationandeffortsthroughouttheyears,culminatinginprojects
suchasthisbook.Overthecourseoftheyears,manyfriendshavehelpedbothSaiandme
growinmanyways.Forthisreason,Iwouldliketosayabigwordofthanks,inno
particularorder,toRikaCatherineHirachi,AnnaLiuJao,ShirupaGupta,PatrickNguyen,
VishnuPrasadRamachandran,AndrewEib,ChristopherMa,andKarthikPalaniappan.I
amsureIammissingsomenames,andforthis,Iapologizeinadvance.Iwouldalsolike
tothankmygraciousmentors,Dr.KevinWaldron,Dr.JamesStubbs,RussellSampson,
MukundPatel,andasIfondlycallhim,Cyril“Master”,allofwhomhavegivenmeadvice
andshownmetheway.Iwouldliketoespeciallythankmyfirstcat,Squeaky,andthe
felinesBob,Saxon,andFishbone,thathavefollowedme,forinspiringmeandpushing
metostayontrackandkeepaneyeonthebigpicture.
AbouttheReviewers
SreedharVaddihas4yearsofexperienceinbigdata,4yearsincloudcomputing,and15
yearsinJava.Hisexperienceincludesworkinthefieldsofbigdatasecurity,
biomedical/healthcare,mobilesecurity,financialservices(wholesale,mortgage,
investment,andbrokerage),theWeb(marketplace,crowdsourcing,andadvertising),news
andentertainment,propertyandcasualtyinsurance,softwareproductdevelopment,and
scientificresearch.
Hehashands-onexperienceasanarchitectworkingonenterprisemobileapplications,
Hadoop,SaaS,PaaS,IaaS,thecloud,richenterpriseapplications,n-tierenterprise
systems,EnterpriseApplicationIntegration(EAI)inweb-enablinglegacysystems,IBM
MainframeandSAP,andSOAwebserviceswithJava2andJEE.
HehasalsoworkedinallphasesofSDLC,namelydesigning,developing,performance
testing,andimplementingWeb-2.0,Web-UI,server-side,middleware,andmobile
applications.HehasalsoworkedwithBig5ConsultingandFortune100companies.He
hasledteamsofsizesvaryingfrom2to80acrosstheglobeindifferenttimezones,
cultures,anddialects.
HeisanadministratorofJEEcontainers(Geronimo,WebSphere,Weblogic,JBoss,and
Tomcat)andCDH.Heisalsoatechnicalconsultantatastealthmodestart-upinanimal
careintheclinicaltrialsindustry.Heisadiligentworkerandquicklearnerwithexcellent
problemsolving,presentation,andmentoringskills.
CheukYuispursuingabachelor’sdegreeinelectricalengineeringattheUniversityof
California,LosAngeles(UCLA),withanemphasisoncircuitandsignalprocessing.He
workedonmultipleembeddedsystemsprojectsusingvariousmicrocontrollerssuchas
Arduino,Teensy,andRaspberryPi.AsastudentresearcherfortheELFINCubeSat
MissionatUCLA,healsohashands-onexperienceworkingonprintedcircuitboards,
includingdesigningandtestingavionicsandgroundsupportequipmentboards.Besides
workandstudy,heisalsoanamateurradiooperatorandastronomer.
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Preface
TheRaspberryPiisaquaintexampleoftechnologicalinnovationsthatcomebyonce
everytwoorthreedecadesandsetoffarevolutionthattoucheseveryaspectofhumanlife
fromscientificexplorationtoentertainmenttoeducation.Whatisexcitingthistime
aroundisthatthereareseveralsuchinnovationshappeningsimultaneously.Theymight
soundlike,andareinaway,buzzwords,buttheyareinfactreal,andarechangingour
livesinsomanyways,sofewofwhichweareconsciouslyawareof.Wearespeakingof
innovationsinentrepreneurship,suchascrowdsourcingortheemergenceofDIYwithan
almostcult-likefollowingtoinnovationsintechnologythatarecurrent,suchas3D
printingandInternetofEverything,andinnovationsthatareimpendingsuchas4D
printing,smartmanufacturing,andmuchmore.
TheRaspberryPihasalreadyfoundseveralusesasevidencedbyhundredsofwebsites,
projectexamples,andcrowdsourcingcampaigns.PeoplehaveusedthePitobuildrobots,
teachprogramming,restoreoldgamingconsoles,streamvideos,collectdata,anddomany
otherthings.ThePiitselfhasgonethroughdesigniterationsandcontinuestospur
competingsystems.PeoplehavetakenadvantageofthisandhavehookedupthePito
manydifferentecosystems,expandingitsubiquityandutility.
ThepurposeofthisbookistohelpthosewhoareexcitedabouttheRaspberryPiandhave
projectideasinmind,orwouldsimplyliketogettheirhandsdirtyandpractice
implementingprojectssothattheycanthenusethatknowledgeforotherendeavors.We
triedtotakeapracticalapproach,introducingthePiinthefirstcoupleofprojectthatyou
canskipifyouarefamiliarwiththeRaspberryPiandhaveuseditbefore.Wethendiscuss
projectsofincreasingcomplexity.Wehavealsoattemptedtodiversifytheprojectsto
demonstratevarioususesforthePithroughoutthebook.
Whatthisbookcovers
Project1,HelloWorld,willintroducetheRaspberryPiandremindyouofthingsthatyou
shouldknowasyouproceedthroughthebook.WewillsetuptheRaspberryPiandblink
anLED.
Project2,ARaspberryWebIDEExample,willtakeyouthroughPythondevelopment
usingabrowser.WewillusetheAdafruitWebIDEandleadyouthroughthedevelopment
processusingAdafruitproductsaspropsfortheexamples.
Project3,TheArduinoRaspberryPiInterface,isinspiredbytheHarryPotterseries,and
inanefforttoshowourloveforthisseries,wehavecreatedaclocksimilartothe
innovativeandendearingWeasleyclockusingtheRaspberryPiandanArduino.This
project,ofcourse,allowstheclocktoreportbackweatherconditions.
Project4,ChristmasLightSequencer,discussesholidaysasthebesttimeforDIYprojects,
andifyouareeverstarvedofideas,holidaysarethebesttimetocookupideas.Wepicked
aChristmas-themedprojecttodemonstratecontrollingappliancesconnectedtoalocal
networkusingRaspberryPi.
Project5,InternetofThingsExample–AnE-mailAlertWaterFountain,followsthe
themeofthepreviousproject.Wewillshowyouhowtocontroladecorativefountainsuch
thatanytimeyoureceiveanewe-mail,yourfountain’slightwillflashanalert(thiscan
alsobeswitchedtoreceiveTwitteralerts).
Project6,RaspberryPiasaPersonalAssistant,willshowyouhowyoucanusethePias
yourpersonalassistant,remindingyouofchores,settingalarms,anddoingeverythingat
yourcommand.
Project7,RaspberryPi-basedLineFollowingRobot,willtakeyouthroughthesimplestof
allrobots,thelinefollowingbot,withRaspberryPiatthehelm.Thisprojectwillshow
youthewayforthisandothercomplexroboticsprojectsyouwishtoimplement.
Project8,ConnectFourDesktopGameusingRaspberryPi,followstheinstant-classic
themefortheRaspberryPi,whichincludesgames.Allmannersofgamingapplications,
includingtherevivalofarchaicgamestonewonesandmods,arebeingcreatedusingthe
RaspberryPi.Wewillimplementthegameusingapushbuttoninterface.
Project9,TheRaspberryPi-enabledPet/WildlifeMonitor,willwalkyouthroughafun
exampleofabirdfeedermonitorthatallowsyoutotriggeraphotocaptureeachtimethe
birdapproachesthefeeder.Youcanthinkofextendingthistootherpets,orsay,theferal
catsinyourcolony.
Project10,RaspberryPiPersonalHealthMonitor,isaprojectwherewesetupasimple
webservertorecordourpersonalhealthparameters,buildasimpletooltoremind
ourselvestoremainphysicallyactive,andremindourselvestorefillaprescriptionviae-
mailalerts.
Project11,HomeAutomationusingRaspberryPi,isaprojectwherewewillshowyou
howtocontrolappliancesusingatwistednetworkwheretheapplianceisconnectedtoa
platformsuchasanArduino.TheRaspberryPiactsasaserverthatcontrolsallsuchnodes
inthenetwork.
Project12,UsingaRaspberryPiforScienceandEducation,isaprojectpackedwith
examples,includingavocabularylearningtool,awebhostforKhanAcademy,anda
windmillgeneratorscienceexhibit.Havefunlearningandteaching!
Project13,TipsandTricks,isaprojectpackedwithtipsandtricksthatwillhelpyouuse
theRaspberryPi!
Youcanalsogetthevideos,tipsandtricks,andmanymorethingsrelatedtotheprojectsat
http://diywithpi.com/.
Whatyouneedforthisbook
Togetstarted,youwillneedtheRaspberryPi,amonitor,akeyboard,apowersource,and
preferably,alaptoporpersonalcomputerrunningonanyOS—Windows,Linux,orApple.
Otherhardwareandsoftwarerecommendationsaremadeintheindividualprojects,and
youarewelcometoreplacethemwithwhatyouseefit.AworkingknowledgeofPythonis
preferred,butnotrequired.
Whothisbookisfor
Thisbookisprimarilyaimedathobbyistsanddo-it-yourselfenthusiastsaswellasthose
lookingtoimplementspecificprojectsusinglowcosthardwareandsoftwarecentered
aroundtheRaspberryPi.Basicexposuretoelectronics,programming,andInternetusage
isassumed.Wehavetriedtotakeapragmaticapproach,implementingtheprojectsand
showinghowyoucandothisonyourown.
Conventions
Inthisbook,youwillfindseveralheadingsappearingfrequently.Togiveclear
instructionsofhowtocompleteaprocedureortask,weuse:
Missionbriefing
Thissectionexplainswhatyouwillbuild,withascreenshotofthecompletedproject.
Whyisitawesome?
Thissectionexplainswhytheprojectiscool,unique,exciting,andinteresting.Itdescribes
whatadvantagetheprojectwillgiveyou.
YourHotshotobjectives
Thissectionexplainstheeightmajortasksrequiredtocompleteyourproject.
Task1
Task2
Task3
Task4
Task5
Task6
Task7
Task8
Missionchecklist
Thissectionexplainsanypre-requisitesfortheproject,suchasresourcesorlibrariesthat
needtobedownloaded,andsoon.
Task1
Thissectionexplainsthetaskthatyouwillperform.
Prepareforliftoff
Thissectionexplainsanypreliminaryworkthatyoumayneedtodobeforebeginning
workonthetask.
Engagethrusters
Thissectionliststhestepsrequiredinordertocompletethetask.
Objectivecomplete–minidebriefing
Thissectionexplainshowthestepsperformedintheprevioussectionallowsusto
completethetask.Thissectionismandatory.
Classifiedintel
Thissectionprovidessomeextrainformationrelevanttothetask.
Youwillalsofindanumberofstylesoftextthatdistinguishbetweendifferentkindsof
information.Herearesomeexamplesofthesestyles,andanexplanationoftheirmeaning.
Codewordsintext,databasetablenames,foldernames,filenames,fileextensions,
pathnames,dummyURLs,userinput,andTwitterhandlesareshownasfollows:“Wewill
gothroughtheimportantfeaturesofthepygamemodule,whichisnecessarytobuildour
arcadegame,includingplayingsoundsandcontrollingthemenu.”
Ablockofcodeissetasfollows:
GPIO.output(25,True)
while1:
GPIO.output(25,False)
sleep(1)
GPIO.output(25,True)
sleep(1)
Anycommand-lineinputoroutputiswrittenasfollows:
#cp/usr/src/asterisk-addons/configs/cdr_mysql.conf.sample
/etc/asterisk/cdr_mysql.conf
Newtermsandimportantwordsareshowninbold.Wordsthatyouseeonthescreen,in
menusordialogboxesforexample,appearinthetextlikethis:“clickingtheNextbutton
movesyoutothenextscreen”.
Note
Warningsorimportantnotesappearinaboxlikethis.
Tip
Tipsandtricksappearlikethis.
Readerfeedback
Feedbackfromourreadersisalwayswelcome.Letusknowwhatyouthinkaboutthis
book—whatyoulikedormayhavedisliked.Readerfeedbackisimportantforusto
developtitlesthatyoureallygetthemostoutof.
Tosendusgeneralfeedback,simplysendane-mailto<feedback@packtpub.com>,and
mentionthebooktitleviathesubjectofyourmessage.
Ifthereisatopicthatyouhaveexpertiseinandyouareinterestedineitherwritingor
contributingtoabook,seeourauthorguideonwww.packtpub.com/authors.
Customersupport
NowthatyouaretheproudownerofaPacktbook,wehaveanumberofthingstohelp
youtogetthemostfromyourpurchase.
Downloadingtheexamplecode
YoucandownloadtheexamplecodefilesforallPacktbooksyouhavepurchasedfrom
youraccountathttp://www.packtpub.com.Ifyoupurchasedthisbookelsewhere,youcan
visithttp://www.packtpub.com/supportandregistertohavethefilese-maileddirectlyto
you.
Downloadingthecolorimagesofthisbook
WealsoprovideyouaPDFfilethathascolorimagesofthescreenshots/diagramsusedin
thisbook.Thecolorimageswillhelpyoubetterunderstandthechangesintheoutput.You
candownloadthisfilefrom
http://www.packtpub.com/sites/default/files/downloads/6227OT_ColoredImages.pdf.
Errata
Althoughwehavetakeneverycaretoensuretheaccuracyofourcontent,mistakesdo
happen.Ifyoufindamistakeinoneofourbooks—maybeamistakeinthetextorthe
code—wewouldbegratefulifyouwouldreportthistous.Bydoingso,youcansave
otherreadersfromfrustrationandhelpusimprovesubsequentversionsofthisbook.If
youfindanyerrata,pleasereportthembyvisitinghttp://www.packtpub.com/submit-
errata,selectingyourbook,clickingontheerratasubmissionformlink,andenteringthe
detailsofyourerrata.Onceyourerrataareverified,yoursubmissionwillbeacceptedand
theerratawillbeuploadedonourwebsite,oraddedtoanylistofexistingerrata,underthe
Erratasectionofthattitle.Anyexistingerratacanbeviewedbyselectingyourtitlefrom
http://www.packtpub.com/support.
Piracy
PiracyofcopyrightmaterialontheInternetisanongoingproblemacrossallmedia.At
Packt,wetaketheprotectionofourcopyrightandlicensesveryseriously.Ifyoucome
acrossanyillegalcopiesofourworks,inanyform,ontheInternet,pleaseprovideuswith
thelocationaddressorwebsitenameimmediatelysothatwecanpursuearemedy.
Pleasecontactusat<copyright@packtpub.com>withalinktothesuspectedpirated
material.
Weappreciateyourhelpinprotectingourauthors,andourabilitytobringyouvaluable
content.
Questions
Youcancontactusat<questions@packtpub.com>ifyouarehavingaproblemwithany
aspectofthebook,andwewilldoourbesttoaddressit.
Chapter1.HelloWorld
ItisaHotshotcustomtobeginlearninganythingnewwithaHelloWorldexample.Since
wewillbedoingreallycoolthingsinthisbook,wewillsay“HelloWorld”inaunique
fashion.Inthisproject,wewillusetheRaspberryPitocauseanLEDlighttoblink.This
projectisdirectedtowardsthosewhoarerelativelynewtotheRaspberryPienvironment
asawarm-upexercise.FeelfreetoskipaheadifyouhavealreadydonethiswithyourPi,
thoughwesuggestyoulookthroughandmakesureyouhaven’tmissedanything.
AquickintroductiontotheRaspberryPi
IfwesearchforthetermRaspberryPiovertheweboropentheRaspberryPi
Foundation’swebpage,wewillfindthattheRaspberryPiisacomputerthatisthesizeof
acreditcard.
PartsofaRaspberryPi
FeaturesofaRaspberryPi
TheRaspberryPiFoundation(http://www.raspberrypi.org/)initiallyreleasedthe
RaspberryPimodelB.ThiswasfollowedbytheRaspberryPimodelA.In2014,the
RaspberryPifoundationreleasedvariantsB+andA+.TheRaspberryPimodelsAandA+
(costing25USDand20USDrespectively)donotcomewithanEthernetport,aUSBport
and256MBRAM.ThemodelA+replacedmodelAwhilethemodelB+replacedmodel
B.ThemodelB(price:35USD)camewithanEthernetport,2USBports,and512MB
RAM;modelB+,whichsupersedesmodelB,comeswith40pinGPIOheaderasopposed
to26intheearliermodels,andhas4USBportsandamicroSDcardslotinsteadofthe
SDslot.PertheRaspberryPiFoundationwebsite,modelB+(aswellasmodelA+)
consumeslowerpower,hasbetteraudioandabetterformfactor,whichwecertainly
concurwith.ThemodelA+alsocomeswitha40pinGPIOheaderandamicroSDcard
slot.ThemodelsA+andB+haveninemoreGPIOpinsthantheirpredecessors.
Note
TheRaspberryPi2wasreleasedafterwefinishedwritingthebook.Pleaserefertothe
book’ssitetofindoutmoreaboutgettingstartedwithmodel2.
TheobjectiveofthisbookistobuildcoolprojectsusingtheRaspberryPi.Wewilldiscuss
thecomponentsofRaspberryPifromthisperspective.Ifyouareinterestedinfindingout
moreabouttheRaspberryPi,theRaspberryPiFoundation’swebpagehaspublishedthe
technicalspecificationsofallthecomponents.
First,wewilldiscussthecomponentsavailableontheRaspberryPiandtheuseofthese
componentsinourprojects.ThecomponentsoftheRaspberryPiinclude:
2USBports(1USBportavailableinmodelA)
Ethernetport(availableonlyinmodelsBandB+)
RCAoutput
HDMIoutput
Audiooutput
Lowlevelperipherals,whichinclude:
GPIO(GeneralPurposeInputOutput)
UART/SerialPort(UniversalAsynchronousReceiverTransmitter)
I2C(twowireinterface)
SPI(SerialPeripheralInterface)
WherecanIbuyaRaspberryPi?
Element14andRSComponentsarethemostcommondistributorsoftheRaspberryPiin
theUnitedStates.TheRaspberryPimodelAwasroughlypricedat25USD,whileits
successormodelA+waspricedat20USD.ThemodelBwaspricedat35USDandthe
modelB+ispricedat40USD.Therearealsoaneverincreasingnumberoflocal
distributorssuchasAdafruitandFry’sElectronicsintheUSthatselltheRaspberryPi
foramargin.PleasechecktheRaspberryPiFoundationwebsiteandothersourcesfor
morevendors.
RequirementstogetstartedwiththeRaspberryPi
Inthissection,wewilldiscusstheitemsrequiredtogetstartedwiththeRaspberryPi.We
willneedallthesamethingsthatarerequiredtouseacomputer/laptop.Theyare:
Display
Keyboard
Mouse
Wi-FiAdapter/Ethernetcable
Note
ItispossibletousetheRaspberryPiviaremoteloginusingasecureshell.Thismight
seemdifficulttothosewhoarenewtotheLinuxenvironment.ThesetupoftheRaspberry
PiforremoteloginisexplainedinProject13,TipsandTricks.
TheRaspberryPieLinuxwiki(http://elinux.org/RPi_Hub)haslistedperipheralsthathave
beentestedandconfirmedtohaveworkedontheRaspberryPi.Youhavethefreedomto
chooseperipheralsaccordingtoyourchoice.
Display:TheRaspberryPiisprovidedwithanHDMIoutputandanRCAoutput.It
ispossibletoconnectamonitorthathasanHDMIinput.Itisalsopossibletoconnect
monitorsthathaveaDVIinputwithanHDMItotheDVIcable.
Powersupply:SincetheRaspberryPiconsumes700mAforitsoperation,itis
recommendedthatthereaderusespoweredUSBhubstousedevicessuchasWi-Fi
adaptersasopposedtopluggingindevicessuchastheWi-Fiadaptersdirectlytothe
USBportoftheRaspberryPitoavoidthedeviceresettingitself.
OperatingsystemsontheRaspberryPi
TheRaspberryPifoundationrecommendsthefollowingoperatingsystemsonthe
RaspberryPi.Theyare:
Raspbian
ArchLinuxARM
RISCOS
Youarewelcometochooseanyoperatingsystemofyourchoice.Forbeginners,we
stronglyrecommendtheRaspbianOSforprojects.TheRaspbianisequippedwithtoolsto
getstartedeasily.TheRaspberryPi’sfirmwareisimplementedsuchthattheoperating
systemisloadedfromanSDcard.
GettingstartedwithRaspbian
Inthissection,wewilldownloadanimagefromtheRaspberryPiFoundation’swebpage
toacomputer,flashanSDcardwiththeimage,andsetuptheoperatingsystemonthe
RaspberryPi.Wewillalsotrytowriteandexecuteourfirstexample.
DownloadingRaspbian
ThelatestRaspbianimageishostedontheRaspberryPiFoundation’swebpage
(http://www.raspberrypi.org/downloads/).Thelatestimageatthetimeofwritingthisbook
wasRaspbianwheezy.Weneedtodownloadtheimageandextractittothefolderofour
choice.
RaspbianwheezyontheRaspberryPiFoundation’swebsite
FlashingimageontotheSDcard
WewilldiscussflashingtheSDcardwiththeRaspbianimageonbothWindowsand
Linuxmachines.
Windows
Extractthefilestoalocationofyourchoice.TheWin32DiskImagertoolisrequiredto
preparetheSDcardwiththeRaspbianimage.
Tip
AstandardRaspbianimageisabout1.8GBbig.Itisstronglyrecommendedthatyouuse
anSDcardthatisatleastof4GBbig.
TheWin32DiskImagertool
WecanflashtheSDcardinthreesimplesteps(asshownintheprecedingscreenshot):
1. SelecttheSDcardthatneedstobeflashed.
2. SelecttheRaspbianimagelocation.
3. ClickonWrite.
4. ClickonYestoconfirm.
ConfirmoverwritingtheSDcard
5. Itcantakeawhilebeforethewritecycleiscompleted.
Linux
TherearetwoidenticalmethodstoflashanSDcardonaLinuxmachine.Thetwo
approachesinclude:
AGUI-basedapproach
Acommand-lineinterface-basedapproach
Acommand-lineinterface-basedapproach
TheSDcardcanbeflashedinthreesimplestepsusingacommand-lineinterface.These
stepsareasfollows:
1. IdentifytheSDcardmountpoint.
2. UnmounttheSDcard.
3. FlashtheSDcard.
IdentifyingtheSDcardmountpoint
AssoonasweinserttheSDcardintoaUSBcardreaderoranSDcardslotfoundona
laptop,weneedtoopenaterminalonourLinuxmachine.Weneedtoidentifyourdevice’s
mountpointonthemachineusingthefollowingcommand:
df–h
Thedevicesenumeratedonthemachinewillbelistedasshowninthefollowing
screenshot:
Storagedevicesidentifiedbytheoperatingsystem
UnmounttheSDcard
Inthepreviousexample,the/dev/sdb5pathisthestoragedeviceofinterest.Theremay
bemorethanonestoragedevicethatmightbeconnectedtoamachine.Weneedtomake
surethatwehaveidentifiedtherightdevice.Oncewehaveidentifiedthedevice,ithasto
beunmountedusingthefollowingcommand:
umount/dev/sdb
FlashtheSDcard
Now,wewillflashourSDcardusingthefollowingcommand:
ddbs=4Mif=~/2012-09-18-wheezy-raspbian.imgof=/dev/sdb
Theif=argumentpointstothelocationoftheimageandof=referstotheSDcardmount
point.Thewriteoperationtakesawhiletocompleteanditisreadyforuseonthe
RaspberryPiuponcompletion.
GUI-basedapproach
OnaDebianLinux-basedoperatingsystem,thereisapackagecalledusb-imagewriter.
TheImageWriterpackageperformsthesameoperationsrequiredtoflashanSDcard.
AUSBImageWriteronUbuntu
SettinguptheRaspberryPi
Nowthattheimageisflashed,let’sgetstartedwithsettinguptheRaspberryPiforthefirst
time.WewillhavetoinserttheSDcardslotfoundontheothersideoftheRaspberryPi.
AflashedSDcardintheslot
Whenthekeyboardandthemouseareconnected,wecangetstartedbypoweringupthe
RaspberryPi!
OncetheRaspberryPiispoweredup,theoperatingsystembootsuptoRaspi-config.The
raspi-configisthetoolusedtosetupdesktopoptions,keyboardsettings,storage
settings,andsoon.TheRaspi-configscreenisshowninthefollowingscreenshot:
TheRaspi-configscreen
Inthissection,wewilldiscusseachfeatureoftheraspi-configtool:
info:Asthenamesuggests,thissectiongivesthegeneralinformationaboutthetool.
expand_rootfs:WhiletheSDcardisflashedwiththeoperatingsystemimage,the
SDcardispartitionedjustaboutthesizeoftheimage.Thiscommandaidstoexpand
thepartitionsothattheremainingspacecanbeusedforfilestorage.
overscan:ThisisanoptionusedwhentheRaspberryPiisconnectedtothe
television.
configure_keyboard:Thisoptionisusedtoconfigurethechange_typeoptionofthe
keyboard.
change_pass:Thedefaultpasswordisraspberry,andifnecessary,thisoptionlets
youswitchtoastrongerpassword.
change_locale:Theoptionletsyouchangethelanguagepreferences.
change_timezone:Wecansetourcurrenttimezoneusingthisoption.
memory_split:ThisoptionletsussplitthememorybetweentheARMprocessor’s
CPUandthegraphicsprocessor.
overclock:Thedefaultclockspeedis700MHz.Thisoptionletsyousettheclock
speedto1GHz.ThismightvaryforRaspberryPi2.
ssh:Thisoptionenablesthesecureshellserver.Thisisrequiredtoremotelylogin
theRaspberryPiandcontroldevicesremotely.ItisenabledbydefaultonRaspbian.
boot_behaviour:Thisoptionenablesyoutobootdirectlyintothedesktop.
Tip
Itisimportantthatyouenablethisoptiononasthedefaultoptionbootsintoanormal
text-basedconsole.
update:IftheRaspberryPiisconnectedtotheInternetusinganEthernetcable,the
raspi-configtooldownloadsanypackagethatmightbeavailable.
OncewecompletethesetupprocessbyselectingFinish,theRaspberryPirebootsand
expandsthefilesystemifnecessary.
Missionbriefing
Inthisproject,wewillsetuptheGPIO(GeneralPurposeInputOutput)peripheralon
theRaspberryPiandwriteourfirstprogramtocauseanLEDtoblink.Attheend,wewill
repeatthesamestepswithaRaspberryPiadd-onboardcalledPiCrust.Thiswillallow
youtogetyourfeetwetandensureyouhavealltherighttoolsgoingforward,andshould
youneedto,troubleshootanyproblemsyoumightidentify.
Whyisitawesome?
Thinkofsaying“HelloWorld”asbothanodtoprogrammingtraditionandadryrunto
ensureyouarewellequipped!
YourHotshotobjectives
Theobjectivesforthismissionarequitesimple,andyettakeusallseveralmilestones
further!HerearetheobjectivesoftheHelloWorldmission:
Collectallthenecessarytools
SetuptheGPIOperipheral
IntroduceourselvestotheRaspberryPienvironment
Turnalightemittingdiode(LED)onandoffwitha1seconddelay
Missionchecklist
Goovertheprevioussections,andmakesureyouhaveallthetools.DownloadtheGPIO
libraries,andensureyoucanlogintotheRaspberryPiremotely,andyouareallset!
Note
TherearetwodifferentwaystouseaRaspberryPi.Theyare:
ConnectingamonitortotheHDMIportortheRCAjackandakeyboardtotheUSB
portoftheRaspberryPi.
RemotelyloggingintotheRaspberryPifromthereader’sworkstation.
Ifyouareabeginner,itisbesttousethefirstmethodwhilethesecondmethodcanbe
usedifyouarefamiliarwiththeLinuxoperatingsystemandremotelogincapabilities.
OncewecompletethesetupprocessbyselectingFinish,theRaspberryPirebootsand
expandsthefilesystemifnecessary.
Huntingandgathering
Asstatedbefore,youwillneedtomakesureyouhaveallthetools.So,goahead,huntand
gatheraway.Grabatleastoneofeachofthefollowingandmorethanoneofeach,ifyou,
likeus,arepronetoaccidents:
AlaptoptodownloadtheRaspberryPiimageandsetupeverything
RaspberryPi—ModelB/B+(preferred),akeyboard,andamousefortheRaspberry
Pi(optional)
SDcardwith4GBmemory(SDcardpreparationwasexplainedearlierinthis
project)
USBPowerAdapter(Rated1.0A)andMicroUSBpowercable
Ethernetcable
Wi-Fiadapter—(optional)refertotheeLinuxwikiforRaspberryPiforverified
peripherals
Breadboard
Jumperwires
DiscreteResistorValues
Aworkbench(oracleanworkingsurface—hopefullyyouhaveone)
Goodthoughtsandacan-doattitude
Lotsofcoffee,tea,orasafebeverageofyourchoice
Engagethrusters
Youwillneedallofthetoolslistedintheprevioussectiontogetthroughthisproject.Take
yourtimeandmakesureyouhaveeverythinghandy!
Objectivecomplete–minidebriefing
Doyouhaveallthetools?Readytogo?Thenontothenexttask!
SettinguptheGPIO
WeneedtoenabletheGPIOperipheralsinourRaspbianinstallationtogetstarted.In
ordertodownloadtherequiredtoolsandsetthingsinmotion,theRaspberryPineedstobe
connectedtotheInternet.
TheGPIOpinisapinthatisavailablefromtheRaspberryPi’sprocessorthatenables
interfacinginputandoutputdevicestotheRaspberryPi.Inthissection,wewilltalkabout
settinguptheGPIOforinterfacinganoutputdevice.Thereisa26-pininterface(40in
ModelB+)availableontheRaspberryPiandabout17ofthose26pinsareGPIOpins(26
oftheminModelB+)whiletheothersaremiscellaneouspinssuchaspower.Thepinsare
drivenbya3.3VrailandeachGPIOpinisratedforabout17mAandthetotalcurrent
drawnotexceeding50mA.
Engagethrusters
WealsoneedtoknowtheGPIOperipheralsavailabletoconductourexperiment.The
followingfigureshowstheGPIOmapsoftheRaspberryPiRev1andRev2:
GPIOmapforModelsA,B,andB+.(ImagepublishedwithpermissionfromRaspi.tv)
TheletterP1showninthefollowingimagecorrespondstoP1-1oftheGPIOmap.P1-1
correspondstothefirstpinontheleftinthefrontrow,whileP1-2correspondstothefirst
pinontheleftinthebackrow.
TheRaspberryPiGPIOperipheral
Inthisbook,wewillbemostlyusingPythonprogramminglanguage.Pythonisavery
simpleandeasylanguagetolearn.Wemaywanderofftootherprogramminglanguages
fromtimetotime,butwewillmostlysticktoPython.Withthisinmind,let’sgetstarted.
InstallingGPIOlibraries
TherearealotoflibrariesavailabletoaccesstheGPIOperipheral.Theeasiesttoinstall
anduseisthequick2wirepythonAPI.TheAPIisusedtocontroltheGPIOperipherals
andI2CdevicesconnectedtotheRaspberryPi.
Note
TherearedifferentlibrariessuchastheRPi.GPIO,Pi4J,andsoon.Weareusingthe
quick2wireAPIinthisexampleasabeginnermightfinditeasytouse.Youarewelcome
touseotherlibrariesofyourchoice.Thequick2wire-gpio-admintoolenablescontrolling
theGPIOpinswithoutrootaccess.
Onedisadvantageofusingthequick2wiremoduleisthatitprovidesaccessonlytoGPIO
pins0through7.
Theterminalcanbelocatedintheleftcornerofthedesktopandhasbeenhighlightedin
thefollowingscreenshot:
ACommand-lineterminalontheRaspbiandesktop
1. Thequick2wirelibraryinstallationisbasedonapostonthequick2wirewebsite
(http://quick2wire.com/articles/how-to-add-quick2wire-as-a-raspbian-software-
source/).Inordertoinstallthequick2wire-pythonlibrary,therepositoryneedstobe
addedto/etc/apt/sources.list.
Inthecommandline,therepositoryisaddedbyusingthenanotexteditor:
sudonano/etc/apt/sources.list
Thefollowinglinesneedtobeaddedtothefile:
#Quick2WireSoftware
debhttp://dist.quick2wire.com/raspbianwheezymain
deb-srchttp://dist.quick2wire.com/raspbianwheezymain
ThefilecanbesavedbytypingCTRL+X.Thefilecanalsobesavedbypressing
Ykeywhileexitingtheeditor.
Alternatively,thelinescanbeaddedusingagraphicaltexteditorsuchas,
leafpadandsavingit:
sudoleafpad/etc/apt/sources.list
2. Inordertoensurethatthepackagesaredownloadedfromthequick2wirerepository,
weneedtoauthenticatethepackagesusingakeyavailablefromquick2wire:
wgethttps://raw.githubusercontent.com/quick2wire/quick2wire-software-
users/master/software@quick2wire.com.gpg.key
sudoapt-keyadd
software@quick2wire.com.gpg.key
3. Thecacheisupdatedandthelatestsoftwarepackagescanbedownloadedasfollows:
sudoapt-getupdate
sudoapt-getupgrade
4. Thequick2wiretoolisinstalledasfollows:
sudoapt-getinstallquick2wire-gpio-admin
sudoapt-getinstallquick2wire-python3-api
Objectivecomplete–minidebriefing
Now,wasn’tthateasy?Let’sgetmorefamiliarwiththeGPIOinput/outputoperations.
GPIOprogrammingusingPython
Inthissection,wewillensurethatthelibraryiscorrectlyinstalledandaddtheusertothe
group.ThiswillenabletheusertousetheGPIOpinswithouthavingrootprivileges.This
willbefollowedbythesectionongettingstartedwithGPIOcontrolprogrammingin
Python.
Engagethrusters
InordertogetstartedwithprogrammingintheRaspberryPi,wewilllaunchPython
IDLE3fromthedesktop.
LaunchingIDLE3fromthedesktop
1. Now,wehavetogetstartedwithprogrammingtheLEDblinkingexampleinIDLE3.
2. ThisLEDblinkingsamplecodeisasfollows:
fromtimeimportsleep
fromquick2wire.gpioimportpins,Out
withpins.pin(7,direction=Out)asout_pin:
whileTrue:
out_pin.value=1
sleep(1)
out_pin.value=0
sleep(1)
out_pin.unexport()
3. Wewillimportthesleepclassfromthetimemoduleinthefirstline.Thisisrequired
tointroducea1-seconddelaybetweenturningtheLEDonandoffeveryother
second:
fromtimeimportsleep
4. Wealsoneedthepinclassfromthequick2wireGPIOlibrary:
fromquick2wire.gpioimportPin
5. Weneedtosettheoutputpinthatwewillbeusingintheexample:
LED_output=Pin(8,Pin.Out)
6. Wecansetthepintothelogicalhigh(3.3V)asfollows:
LED_output=1
7. Wewillsetthepintothelogicallow(0V)asfollows:
LED_output=0
8. Wewillexecutethesamethingusinganinfinitewhileloop:
whileTrue:
LED_output=1
sleep(1)
LED_output=0
sleep(1)
9. ThiswillmaketheLEDblinkwitha1-seconddelay.Weshouldalsonotetheindent
ontheblinksequence.Theblinksequencehasadifferentindentcomparedtothe
whileloop.Hence,thecodethatisatadifferentindentisexecutedinfinitely.
10. Whentheprogramisinterrupted(bypressingCTRL+Conthekeyboard),weneed
tounexportthepinsatexit:
out_pin.unexport()
Analternativetoquick2wire–RPi.GPIO
1. AnotheralternativeistouseRPi.GPIO(https://pypi.python.org/pypi/RPi.GPIO).It
comesasastandardpackagealongwiththeRaspbianWheezyOS.Let’sperforma
quickreviewofthecode:
importRPi.GPIOasGPIO
fromtimeimportsleep
GPIO.setmode(GPIO.BCM)
GPIO.setup(8,GPIO.OUT)
GPIO.output(8,GPIO.LOW)
whileTrue:
GPIO.output(8,GPIO.HIGH)
sleep(1)
GPIO.output(8,GPIO.LOW)
sleep(1)
GPIO.cleanup()
2. Afterimportingtherequiredmodules,wegetstartedwithsettingupthepin
numberingmode.Therearetwotypesofpinnumberingmodes,namely:
TheBCMPinnumberingmode:Thepinnumbersarebaseduponthepin
numbersoftheBCMchip.
TheBoardnumberingmode:Thepinnumbersarebaseduponthepin
numbersoftheRaspberryPiGPIOheader.
Inthisexample,wewillsettheBCMnumberingmodeandsetpin8asthe
output:
GPIO.setmode(GPIO.BCM)
GPIO.setup(8,GPIO.OUT)
3. Wecansetthepintologicalhigh(3.3V)asfollows:
GPIO.output(8,GPIO.HIGH)
4. Wecansetthepintologicallow(3.3V)asfollows:
GPIO.output(8,GPIO.LOW)
5. Now,theLEDcanbemadetoblinkwitha1seconddelay:
whileTrue:
GPIO.output(8,GPIO.HIGH)
sleep(1)
GPIO.output(8,GPIO.LOW)
sleep(1)
6. WhentheprogramisinterruptedbytypingCTRL+C,wehavetocleanupand
releaseanyoccupiedGPIOresources:
GPIO.cleanup()
Objectivecomplete–minidebriefing
Inthissection,wefinishedwritingaprogramtomakeanLEDblink.Inthenextsection,
wewillputacircuittogetherthatmakesanLEDblink.
Electricaloutputofourprogram
Intheprevioussection,wewroteaprogramtomakeanLEDblink.Let’slookatthe
electricalconnectiontoobservetheoutputofourprogram.Wewillconnectaresistor
betweentheGPIOpinandtheanodeoftheLED.Wewillconnectthecathodetothe
groundpinoftheRaspberryPi.
Engagethrusters
WewillconnecttheLEDandtheresistortotheGPIOpinandthegroundpin,asshownin
thisimage:
LEDblinkingcircuit
Note
IfwearenotcarefulwiththehandlingoftheRaspberryPiGPIOpins,itmayeither
temporarilyresettheRaspberryPiorsometimesevenpermanentlydamagetheGPIOpin.
ThereareseveraltutorialsinbasicelectronicsavailableovertheWeb.Itisimportantthat
youfamiliarizeyourselfwiththebasicsofelectronics.
Onceweconnectthecircuitasshownintheprecedingimage,wewillbeabletoexecute
theprogramandconcludeourexperiment.
Wecanexecutetheprogrambyrunningthemodule,asshowninthefollowingscreenshot:
ExecutingthePythonexample
Objectivecomplete–minidebriefing
That’sit!WehavewetourfeetbysayingHelloWorldbyblinkinganLED!Onourwayto
biggerandbetterthings,let’sstopandexaminethePiCrustforamoment.
IntroductiontothePiCrust–aprototypingplatformfortheRaspberry
Pi
NowthatourHelloWorldexampleisdone,wewillleaveyouwithonemorething.
Throughoutthisbook,wewillreviewsomeadd-onhardwaretoaccesstheGPIO
peripheralsontheRaspberryPi.Inthisproject,wewilldiscussthePiCrustboardforthe
RaspberryPi.
ThePiCrustboardwasdesignedbyJoeWalnes.Itisaboardthatisstackableonthe
RaspberryPiandeliminatestheneedforabreadboardtoprototypecircuits.
APiCrustboard
ThePiCrustisanopensourceadd-onhardwareandcostsapproximately$14tobuildone
ourselves.Thedesigncanbedownloadedfreeofcostfromhttp://picru.st.
So,itisuptoyoutodecidewhetheryouwanttosimplybuyone,buildone,orasweare
pronetoencourage,improveuponitandopensourceitforotherstobenefit!
ThemainadvantagebehindPiCrustisthatitisaidsprototyping.Itallowseasyaccessto
theI2Cinterface,SPIinterface,UARTport,andtheGPIOpins.Thefollowingfigure
showsBlinkM—anI2C-drivenRGBLEDmountedontopofthePiCrust.
PiCruststackedontopoftheRaspberryPi
Missionaccomplished
Nowthatyouhavetraveledthisfarwithus,howdoyoufeel?Doyouneedabreak,or
morecoffee?Beforeyoudoeither,let’sreview.
Inthisproject,wegotstartedwiththeLEDblinkingexampleusingtheRaspberryPi.We
discussedthesetupofGPIOperipheralsandusingtheminanexperiment.Youare
welcometocontinueexperimentswiththeGPIOperipheralswithprojectssuchasLED
sequencing,threebitcounter,andsoon.
Intheforthcomingprojects,wewilllookintoI2Ccommunication,SPIcommunication,
andUARTcommunication(serialport).
Hotshotchallenge
Welldone;youhavetaughtyourPitosay“HelloWorld”!However,wearesureyoucan
domore,muchmore.HaveyouwatchedthemovieCloseEncountersoftheThirdKind?
Well,ifnot,youshould.However,thisisnotachallengeinitself.Inthemovie,thehuman
beingsattemptatcommunicationwithwhattheybelieveisaliensbybuildingapatternof
lightsthataresettomusic.CanyoumakeapatternofLEDsrepeatthatorsomething
similar?
Chapter2.ARaspberryWebIDE
Example
Inthisproject,wewilllearnhowtodevelopprojectsusingtheWebIDEfromAdafruit
Industries.WewillflashanSDcardwiththeRaspbianOS,installtheOccidentalistool
(https://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/occidentalis-v0-
dot-3),setuptheweb-baseddevelopmenttool,andtestthesetupusinganexample.
Note
OccidentaliswasinitiallyavailableasaRaspbianOSimagebyAdafruitIndustries.It
comprisedofthetoolsetthatenabledtogetstartedwithprojectdevelopmentusingthe
RaspberryPi.TheOSimagewasdeprecatedandreleasedafterwefinishedwritingthe
book.Wehavetakenourbestefforttoupdatethebook.Pleaserefertothisbook’swebsite
formoreinformation.
Missionbriefing
Inthisproject,wewilldiscussinstallingatool,Occidentalis,andaWebIDEthatenables
programminginthePythonlanguageontheRaspberryPi.Wewillalsodiscussone
examplefromtheAdafruitrepositoryandanotherexampleofdrivinganRGBLED.
Thefollowingtableliststhebillofmaterialsusedinthisproject.Thesearejustexamples,
andalternativeproductsthathaveasimilarspecificationmayalsobeused.
Item EstimatedCost
RaspberryPiModelB 35USD
AdafruitCobbler(https://www.adafruit.com/product/914) 7USD
Adafruit7-segmentLEDBackpack(https://www.adafruit.com/product/879) 10USD
Blinkm(https://www.sparkfun.com/products/8579) 13USD
Whyisitawesome?
TheAdafruitWebIDEincombinationwiththeOccidentalisoperatingsystemenables
developmentinthePythonlanguageonaRaspberryPiusingjustawebbrowser.Italso
enablesaccesstosampleprojectsdevelopedbyAdafruitviaBitbucket,asourcecontrol
tool.(IfyouarenotfamiliarwithsourcecontroltoolssuchasBitbucket,Git,andsoon,
theexamplesinthisprojectareagreatwaytogetstarted!)TheAdafruitWebIDEisatool
developedforhobbyistsandcomeswithexamplesfortechniquessuchaspulse-width
modulation(usedinlightingsystemcontrol)andI2Ccommunication,andalsoprovides
examplesforcontrollingproductsfromAdafruit.
Note
TheAdafruitWebIDEisnowabetareleaseanditmaynotworksuccessfullyacross
differentplatforms.TheAdafruitlearningsystemhasindicatedthatthisdevelopmenttool
wasdirectedtowardsadvancedhobbyists.Wehavetakenourbesteffortstoexplainitas
simplyaspossible.
Pulse-widthmodulationisatechniqueusedwidelyinmotorcontrol,lightingsystems,and
soon.Itisatechniquewheretheaveragevoltageappliedtoadeviceisvariedbychanging
thewidthofthepulse.Thereareseveraltutorialsonpulse-widthmodulation
(https://learn.sparkfun.com/tutorials/pulse-width-modulation)availableallovertheWeb.
I2Ccommunication(https://learn.sparkfun.com/tutorials/i2c)isaformofserial
communicationinterfaceusedtoconnectmultipleslavedevices(usuallysensors)witha
masterdevice(RaspberryPioramicrocontroller)throughacommoninterface.
YourHotshotobjectives
Inthisproject,wewilldiscussthefollowingfeatures:
BootstrappingyourRaspberryPibyinstallingOccidentalis
SetupofremoteloginintotheRaspberryPi
InstallationoftheRaspberryPiWebIDE
PythondevelopmentontheWebIDE
TestanddebuggingexamplesusingtheWebIDE
Note
ThisprojectshouldnotbeconsideredasanattempttopromoteAdafruitIndustriesor
theirproductsdevelopedfortheirplatform.Thisprojectmerelydemonstrates
simplificationofdevelopmentontheRaspberryPiusingatoolfromAdafruit
Industries.
Missionchecklist
Inordertogetstarted,thefirststepistoinstalltheOccidentalisdistro,whichisa
derivativeoftheRaspbianoperatingsystem.
Thethingsrequiredtogetstartedareasfollows:
A4GBSDcardflashedwiththeRaspbianOS
AnOccidentalisimage.
AnEthernetcable
Installation,features,andusageofthe
Occidentalisoperatingsystemfrom
Adafruit
ThefirststepisinstallingOccidentalisontheRaspberryPi.
Prepareforliftoff
ThefirststepistheinstallationoftheAdafruit-Pi-Findertool.Thetoolcanbedownloaded
fromhttps://github.com/adafruit/Adafruit-Pi-Finder/releases/latest.Itisavailablefor
Windows,Linux,andMacplatforms.
Engagethrusters
1. YoucanfinddetailedinstructionsoninstallingtheOccidentalistoolat
https://github.com/adafruit/Adafruit-Pi-Finder.
2. Alternatively,astep-by-stepinstructionisalsoavailableonthisbook’swebsite.We
cannotincludethemheresincechangesweremadetoOccidentalisinstallation
processafterwefinishedwritingthisbook.
Objectivecomplete–minidebriefing
Oncetheinstallationiscomplete,wehavetoensurethattheRaspberryPiaswellasthe
developmentmachineareconnectedtothenetworkviatheEthernetportoraUSBWi-Fi
dongle.
SetupofaremoteloginintotheRaspberry
Pi
Inthissection,wewillremotelylogintotheRaspberryPiusingasecureshell.Sincethe
RaspberryPicomeswithsshdenabled,itispossibletologinremotelyusingthelocal
name,raspberrypi.local(Duringthebootstrappingprocess,theavahi-daemontoolis
installedandhence,itispossibletoremotelylogintotheRaspberryPiusingthelocal
name,raspberrypi.local).Alternatively,onaWindowsmachine,youcanuseatool
suchasAdvancedIPScanner(http://www.advanced-ip-scanner.com/)tofindtheIP
addressoftheRaspberryPi.Asnapshotofthistoolisshownlaterinthisproject.
Note
IfyouareusingaWindowsmachine,theBonjourPrintServicesdrivershavetobe
installedtoremotelyloginusingthelocalname,raspberrypi.local.TheBonjourPrint
Servicesdriversareavailablefromhttp://support.apple.com/kb/DL999.
Prepareforliftoff
TheIPaddressoftheRaspberryPicanbeidentifiedusingtoolssuchasAdvancedIP
Scanner,asshowninthefollowingscreenshot:
AlistofdevicesandIPaddressesconnectedtoanetworksimilartotheRaspberryPi
Engagethrusters
1. OnceweknowtheIPaddress,weuseanSSHclientsuchasPuTTYonWindowsora
command-lineterminalonaLinuxoraMacmachinetoremotelylogintothe
machine(inthiscase,weshowthisonaWindowsmachine).
2. OnaWindowsmachine,weeitherusetheIPaddressoftheRaspberryPioritslocal
name(raspberrypi.local)andlogintotheRaspberryPi,asshowninthefollowing
screenshot:
3. OnceweentertheIPaddress/localnameinthePuTTywindow,weloginas
follows:
loginas:pi
<username>@<ipaddress>'spassword:raspberry
Alternatively,wecanalsologinusingtheIPaddressoftheRaspberryPiinsteadof
thelocalname,raspberrypi.local.
Objectivecomplete–minidebriefing
Iftheusernameandpasswordareenteredcorrectly,weshouldbeabletoremotelylogin
totheRaspberryPitoinstallthewebserver.
InstallationoftheRaspberryPiWebIDE
WewillgetstartedbyusingaremoteloginclientsuchasPuTTYtoremotelylogintothe
RaspberryPiandinstalltheAdafruitWebIDE.Inordertogetstartedwithexamplesfrom
theAdafruitrepository,weneedaBitbucketaccount,andAdafruitprovidesdetailed
instructionsforthisathttp://learn.adafruit.com/webide/getting-started.
Engagethrusters
1. Oncewehaveloggedin,theAdafruitlearningsystem’swebsiterecommends
executingthefollowingtoinstallthewebserver:
curlhttps://raw.githubusercontent.com/adafruit/Adafruit-
WebIDE/master/scripts/install.sh|sudosh
2. Itshouldtakeaboutfiveminutestofinishtheinstallation.Iftheinstallationwas
successful,weshouldbeabletoseethemessagemarkedinthefollowingscreenshot:
SuccessfulcompletionoftheAdafruitWebIDEinstallation
3. Assumingtheinstallationwassuccessful,weshouldbeabletolaunchtheAdafruit
WebIDEusinghttp://raspberrypi.local.
AdafruitWebIDElaunchedforthefirsttime
4. InordertomakeuseoftheexamplesfromAdafruitIndustries,weneedtocreatea
Bitbucketaccount(itispossibletocreateonewithaGoogleaccount)andintegrate
theWebIDEwiththeBitbucketaccount.Theinstructionsforthisareprovidedonthe
webpage,asshownintheprecedingscreenshot.
Objectivecomplete–minidebriefing
Iftheinstallationwassuccessful,aftercompletionoftheregistration,wearedonewith
thistask.Let’smoveonandlearntocodeusingtheWebIDE!
PythondevelopmentontheWebIDE
Inthissection,wewillusea7-segmentLEDbackpackandtheAdafruitCobbleralong
witha26-pinribboncable.WewilltestanexamplefromtheAdafruitrepository
(https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code).Inthisproject,thenew
add-onhardwarethatwewilldiscussistheAdafruitCobbler.TheCobblerisasmall
boardthataidsprototypingcircuitsonabreadboard.TheAdafruitCobblercostsabout7
USDwhiletheribboncablecostsabout3USDandthe7-segmentbackpackcostsabout
10USD.
Note
TheearliermentionedproductsaremerelyexamplestodemonstratetheAdafruitWebIDE.
Therearealternativeprototypingplatformsandproductsavailableforahigherorlower
price.
TheCobblermountedonabreadboard
Prepareforliftoff
Inordertogetstartedwiththeprototyping,the26-pinribboncableisusedtoconnectthe
GPIOinterfacetotheCobbler,asshowninthefollowingimage.Wehavetoensurethat
pin1oftheGPIOheadermatchespin1oftheAdafruitCobbler.(TheCobblercomeswith
ashroudedheader,andhenceitisfoolproof.However,pin1oftheRaspberryPineedsto
bematchedcorrectly.)
QuickintroductiontotheI2Cinterface
TheI2CinterfacewasinventedbyPhillipsSemiconductors.Itisaformofserial
communicationinterfaceusedtoconnectmultipleslavedevices(usuallysensors)witha
masterdevice(RaspberryPioramicrocontroller)throughacommoninterface.Each
devicehasauniqueaddressthatisusedbythemastertoreadorwritedata.Thereare
plentyofresourcesavailabletofamiliarizeourselveswiththeI2Cinterface.Wewillmove
ontothenextstageofconfiguringtheinterface.
ConfiguringtheI2CinterfaceontheRaspberryPi
IntheOccidentalisdistribution,theI2Cdriversareinstalledandenabledbydefault.
Hence,wecangetstartedbyconnectingtheAdafruit7-segmentbackpacktotheAdafruit
Cobbler,asshowninthefollowingimage.(ConnectionsbetweentheCobblerandthe7-
segmentbackpackareClockpin,SCL(C)-SCL(B)DataPin-SDA(C)-SDA(B),3V3(C)
to+(B)GND(C)to-(B),whereCistheCobblerandBisthebackpack):
7-segmentbackpackconnectionsonabreadboard
NowthatwehaveconnectedtheRaspberryPi,theAdafruitCobbler,andthe7-segment
backpack,let’sgetstartedwiththedetectionofthebackpackontheRaspberryPi’sI2C
interfaceandprogramanexample.
Beforewegetstartedwiththeexample,weneedtodeterminetheI2Cbustowhichthe
deviceisconnectedbyusingthefollowingcommand:
sudoi2cdetect–y0
Thecommandoutputsatablethatcontainsthelistofdevicesforthatparticularbus.Since
therearenodevicesconnectedtobus0,wescanfordevicesonbus1.Inthisexperiment,
wearetestingtheAdafruit7-segmentbackpack.Inthefigurethatfollows,the7-segment
backpackisconnectedtobus1andthedeviceaddressis0x70.Refertothefollowing
screenshot:
Thei2cdetectoutput
Weshouldchangethebusaddressinthecodetodrivethe7-segmentbackpack.Line11in
theAdafruit_I2C.pyfileneedstobechangedinthecodeaccordingtothebustowhich
thedeviceisconnected.Hence,line11shouldbe:
def__init__(self,address,bus=smbus.SMBus(1),debug=False):
Engagethrusters
1. The7-segmentbackpackisadevicecontrolledviaanI2Cport.AnyI2Cdevicehas
fourpins,namelyclock,data,powersupply,andground.TheI2Cdeviceneedstobe
connectedtotheCobbler,asshownintheearlierscreenshot.
2. ThereareseveralexamplesavailablefromAdafruitintheWebIDE.Let’slocatethe
ex_7segment_clock.pyexample(intheIDE,itislocatedatAdafruit_Raspberry-
Pi-Python-Code|ex_7segment_clock.py).Thisisasimpleexampletodisplaythe
currenttimeonthe7-segmentbackpack:
Theex_7segment_clock.pyfilelocationintheWebIDE
3. Let’sdoaquickreviewoftheprogram.Wegetstartedbyimportingthedatetime
andAdafruit_7Segmentmodules:
ThesegmentvariableisinitializedasaninstanceofanI2Cdeviceattheaddress
0x70.Weenteraninfiniteloopandgetthecurrenttimeusingthedatetime
module:
now=datetime.datetime.now()
hour=now.hour
minute=now.minute
second=now.second
Sincethe7-segmentLEDbackpackconsistsoffourdigits,wewritethecurrent
timeateachpositionasfollowsalongwithacolon:
#Sethours
segment.writeDigit(0,int(hour/10))#Tens
segment.writeDigit(1,hour%10)#Ones
#Setminutes
segment.writeDigit(3,int(minute/10))#Tens
segment.writeDigit(4,minute%10)#Ones
#Togglecolon
segment.setColon(second%2)#Togglecolonat1Hz
#Waitonesecond
Thisexerciseisrepeatedwithaonesecondinterval.
4. TheprogramisexecutedbyclickingonRunfoundintheIDE.Ifourconnections
wereright,weshouldbeabletoseethecurrenttimeonthe7-segmentdisplay
(showninthefollowingfigure).
Objectivecomplete–minidebriefing
WewereabletotestanAdafruitproductusingtheirWebIDEinthissection.
A7-segmentbackpackconnectedtotheCobbler
Testanddebuggingexamplesusingthe
WebIDE
Inthisexample,wewillconnecttheBlinkMtotheRaspberryPi.ABlinkMisanRGB
LEDthatcanbeconnectedtoyourRaspberryPiviatheI2Cinterface.Itispossibleto
executelightscriptsusingtheport.TheconnectionstotheBlinkMaresimilartothatof
the7-segmentbackpack.
BlinkMconnectedtotheCobbler
Note
ItisimportanttopayattentionwhileconnectingdevicestotheGPIOheaderofthe
RaspberryPi.IftherearedevicesthatdrawalotofcurrentfromtheGPIOpins,itmay
resetthePiorpermanentlydamageitintheeventofashortcircuit.Itisassumedthatyou
arefamiliarwithbasicelectronicsandcapableofhandlingsuchdevices.
Prepareforliftoff
Similartothepreviousexperiment,weneedtodeterminethebustowhichthedeviceis
connectedusingthei2cdetectcommand.Asshowninthefollowingscreenshot,the
deviceisconnectedtobus1andthedeviceaddressis0x09:
Blinkmconnectedtobus1
Engagethrusters
1. TheBlinkMdatasheet
(thingm.com/fileadmin/thingm/downloads/BlinkM_datasheet.pdf)providesstep-by-
stepinformationtoexecutethelightscripts.
2. AlistofscriptsavailableontheBlinkMisshowninthefollowingscreenshot:
AlistofscriptsavailableontheBlinkM
3. Let’sseethecodetoexecutealightscript(forexample,scriptnumber6)onthe
BlinkMusingtheAdafruitWebIDEinterface.Inordertoexecuteascriptforever,the
datasheetmentionsthatthefollowingcharactersshouldbewrittenattheI2Cdevice
addressinthefollowingsequence:'p',<scriptno>,0,0.Let’sdiscusshowto
executethisusingaPythonscriptontheRaspberryPiinterfacedwiththeBlinkM
LED.ThePythonscriptofthisexampleiscalledPlay_blinkm.py:
ThePlay_blinkm.pyfilecanbeexecutedbycreatinganewfileinthe
repositorythatwascreatedwhenyousignedupforaBitbucketaccount.When
thefileissaved,thechangesaresavedtoyourBitbucketaccount.Thecodefor
thisisgivenasfollows:
#!/usr/bin/python
#python-smbus
importsmbus
#createi2cobject
bus=smbus.SMBus(1)
#refertodatasheetforscriptsequence
#Playscriptbywriting0x70orponthebus
bus.write_byte(0x09,0x70)
#playscriptno:6
bus.write_byte(0x09,0x06)
#playthescriptinfinitely
bus.write_byte(0x09,0x00)
bus.write_byte(0x09,0x00)
Thefirstlineofthiscodeiscalledshebang.Itindicatesthatthescripthastobe
executedusingPython.
Weneedtoimportpython-smbustoexecutethelightscript:
importsmbus
WeneedtocreateanobjectforI2Ccommunication.Weneedtowritethe
controlscriptviabus1.Thisisdonebythefollowinglineofcode:
bus=smbus.SMBus(1)
Inordertoplayascript(scriptnumber6inthiscase)forever,wewrite'p',
<scriptno>,0,0ontheI2Cbusasfollows:
bus.write_byte(0x09,0x70)
bus.write_byte(0x09,0x06)
bus.write_byte(0x09,0x00)
bus.write_byte(0x09,0x00)
4. ThiswouldcausetheBlinkMtoexecutescriptnumber6aslongasthedeviceis
poweredanduntilanotherinstructionhasbeenissuedtothedevicethroughtheI2C
interface.
5. Now,itispossibletodebugourprogrambyexecutingitstepbystep.Thishelps
identifyanyproblemswiththeprogram.Let’sreviewsomeoptionstodebuga
program.Wecanlaunchtheprogramfortroubleshooting/debuggingbyclickingon
Debug.
TheAdafruitWebIDEtoolbar
Thisopensuptwoconsoles,DebugOutputandDebugVariables(shownin
thefollowingscreenshot).ThewindowDebugOutputprintsanyoutputofthe
program.Ifweincludedanyprintstatementsinourprogram,theoutputis
displayedinthiswindow.Thiswindowcanbeusedtoviewanyresults,ensure
thataparticularcallbackfunctionwasexecuted,ordeterminewhetherthe
programexecutiongotpastaparticularlineoftheprogram.
TheDebugVariableswindowdisplaysthestateofvariablesastheprogramis
beingexecuted.BoththewindowsarehelpfulindeterminingwhetheraPython
scriptwaswrittenasintended.
Debugterminals
WhenwestartdebuggingaPythonscript,thetoolbaratthetoppresentsuswith
twooptions,namelyStepOverandStepIn,asshowninthefollowing
screenshot:
TheAdafruitdebugtoolbar
Inthisexample,itispossibletotesttheexecutionofcommandsbystepping
througheachlineofthescript.Thisisreallyusefulwhendevices(forexample,
apressuresensor)arenotprovidingtheintendedoutputtoidentifytheroot
cause.
Objectivecomplete–minidebriefing
Inthissection,weinterfacedandcontrolledanRGBLEDusinganI2Cinterfaceand
discussedsomeoptionsavailablefordebuggingintheAdafruitWebIDE.
TheAdafruitWebIDEcanconsiderablyreducetheturnaroundtimeforanyproject
developmentactivity.
Missionaccomplished
Inthisproject,weworkedontwosimpleexperimentsusingtheI2Cinterfaceonthe
RaspberryPi.ThetwoexamplesdiscussedusingtheAdafruitWebIDEreflectthefactthat
thetoolcanhelpsavetimeforanyelectronicsprojectinvolvingaRaspberryPisinceit
comeswithsomeoftheprerequisitesinstalledalongwithawebinterfacethatjustmakes
remotedevelopmenteasier.
WehopethatyouhadfuntakingtheOccidentalisdistributionforatestdriveandfindit
usefulinyourprojects.
Hotshotchallenge
Inthisproject,weusedtwodifferenttypesofI2Cdevices,thatis,anLEDbackpackand
anRGBLED.ItispossibletoconnectmultipleI2Cdevicestothesameinterface.How
canthisbeachieved?HowcanweidentifytheaddressesoftheseI2Cinterface-enabled
devicesandcontrolthem?
Chapter3.TheArduinoRaspberryPi
Interface
Inthisproject,wewilllookintointerfacingtheRaspberryPitotheArduino
microcontrollerdevelopmentplatform.Arduino(www.arduino.cc)isapopular
microcontrollerplatformthatiswidelyusedtoprototypedifferentprojects.Wewill
discussinstallationoftheArduinodevelopmentenvironmentanddiscussanexampleof
itsusage.
RaspberryPiandArduinohavebecomepopularplatformsamonghobbyists,anditis
beingwidelyusedbypeoplefromdifferentbackgrounds,includingschoolanduniversity
students,artists,andengineers.ThisprojectexplainshowtheRaspberryPicanbeusedin
combinationwithArduino.
Note
TheRaspberryPicomeswithaGPIOpinsetthatisquitecapableofinterfacingand
controldevices.WewouldliketodiscusstheArduinoRaspberryPiinterfacebecauseyou
mayhaveprojectsthatwereoriginallybuiltusinganArduino,especiallyinscenarios
wherearemotefirmwareupdateneedstobeperformedontheArduinoplatformusingthe
RaspberryPi.Thisprojectpresentstheoptionsofenhancingthecapabilitiesofthe
ArduinomicrocontrollerusingaRaspberryPi.
Missionbriefing
Inthefirstpartoftheproject,wewilldiscussprogrammingtheArduinoforthefirsttime,
andinthesecondhalf,wewilllookintothecontrolofaWeasleyweatherclock.Wewill
alsolookintotheRaspberryPiAlaMode,stackableadd-onarduinohardware
(http://wyolum.com/projects/alamode/).
Whyisitawesome?
ArduinoisanopensourcemicrocontrollerdevelopmentplatformbasedontheAtmel
seriesofmicrocontrollers.Ithasbroughtengineers,artists,andstudentstothesametable.
Theprogramminginterface(programsarewritteninC/C++usually)issosimpleandthis
wasthesolereasonthatmadetheplatformsopopular.Hence,itiswidelyusedfor
prototypinginproductdevelopment.
Overtheyears,therehavebeenseveralhardwareadd-onsthataidedinhardware
developmentusingtheArduino.Someoftheseadd-onscanbestackedontopofthe
Arduinodevelopmentplatform,andtheyarecommonlyreferredtoasshields.Thereare
shieldsformedicaldevices,interfacingsensors,GPSunits,andactuatorssuchasstepper
motors,servomotors,andsoon.Theecosystemofthegadgetsthatarebuiltaroundthe
Arduinoissovastthatthemicrocontrollerplatformwaslaunchedintothestratosphere
alongwithaheliumballoon.
WherecanyoubuyanArduino?
SincetheArduinoisanopensourcemicrocontrollerboard,therearemanyresellersforthe
product.ThebasicversionoftheArduinoistheArduinoUnoandcostsabout$29.95.
Arduino-relatedproductsaresoldatwebsitessuchasSparkfun,Adafruit,andSeeed
Studio.
YourHotshotobjectives
Inthisproject,wewilldothefollowing:
InstalltheArduinoIDE
ProgramtheArduinousingtheRaspberryPi
RaspberryPiAlaMode(oranyotherArduinodevelopmentboard)
IntroductiontoWeasleyWeatherClockandBillofMaterials
ControlthestepperusingtheArduino
ControltheRGBLEDStripusingtheArduino
I2CCommunicationusingtheArduino(optional)
SerialportcommunicationwiththeRaspberryPi
Missionchecklist
WeneedaRaspberryPialongwithanSDcardflashedwiththeRaspbianOS,amicro
USBpowercable,displaysetup,andanArduinotogetstarted.Inthelatersectionofthis
project,wewillneedsomeadditionalhardwaresuchasRGBLEDStrips,motors,wires,
andsoon.
InstallingtheArduinoIDE
Inthissection,wewillinstalltheArduinoIDEontheRaspberryPi.
Prepareforliftoff
AnArduinomicrocontrollerdevelopmentplatform(anyvariantthatcouldbeprogrammed
usingtheArduinoIDEisfine)isabsolutelyessentialforthissectionoftheproject.
Engagethrusters
1. TheIDEcouldbeinstalledbyexecutingthefollowingcommandinthecommand
lineterminal:
sudoapt-getinstallarduino
2. MostArduinoproductscomewithaUSBportandareprogrammedviatheUSBport
(theArduinoenumeratesasaserialportdevice).Ittakesawhiletodownloadand
installtheArduinoIDE.Oncetheinstallationisfinished,wecantesttheinstallation
byexecutingthefollowingcommand:
arduino
TheArduinoIDEisshowninthefollowingscreenshot:
TheArduinoIDEinterface
Objectivecomplete–minidebriefing
NowthatwehaveinstalledtheArduinoIDE,let’smoveontothenextsectionandrunan
exampletestusingtheArduinodevelopmentplatform.
ProgrammingtheArduinousingthe
RaspberryPi
WewillintroduceourselvestotheArduinoIDEwithanLEDblinkingexample.
Prepareforliftoff
ThereareseveralexamplesfortheArduinoandittakeslessthanaminutetoexecutethe
firstprogram.Let’sgetstartedwiththetraditionalLEDblinkingexample.TheLED
blinkingexamplecanbefoundatFile|Examples|01.Basics|Blink.
Engagethrusters
1. WegetstartedbyidentifyingtheArduino’sserialportenumeratedontheRaspberry
Pi.
2. TheserialportisidentifiedfromTools|SerialPort.Usuallythereisonlyoneserial
portasshowninthefollowingscreenshot.Ifthereismorethanoneserialportdevice
connected,itisrecommendedthatyouproceedwithcaution.
3. WecanprogramtheArduinobyclickingontheUploadbutton.
TheArduinoIDEinterface
Objectivecomplete–minidebriefing
IftheArduinoisconnectedandtheserialportwascorrectlyidentified,theprogramshould
beuploadedsuccessfully.
SketchuploadedusingtheArduinoIDE
MostArduinoproductscomewithanonboardLEDtotesttheLEDblinkingexample.
RaspberryPiAlaMode
Inthissection,wewillbrieflydiscusstheRaspberryPiAlaMode’sfeaturesanditssetup.
RaspberryPiAlaMode(asshowninthefollowingfigure)isastackableArduino
developmentplatformdevelopedspecificallyfortheRaspberryPi.Theboard,whichis
releasedasopensourcehardware,ispricedatabout$45andalsoincludesareal-time
clockandamicroSDcardslotfordatalogging.
RaspberryPiAlaModemodestackedontheRaspberryPi
Prepareforliftoff
TheattractivefeatureoftheboardisthatitcouldbeprogrammedviatheRaspberryPi’s
UARTpinsandhenceeliminatestheneedforaUSBport.Theboardcouldbeeither
poweredviatheRaspberryPiorthroughtheMicroBUSBportusingawallwart
transformer.Theproduct’swebpage,http://wyolum.com/projects/alamode/alamode-
getting-started/,offersasinglestepprocesstostartusingtheboard.
Note
TheRaspberryPiAlaModemodeisjustoneexampleofthestackableArduinohardware.
ThereareprobablyothersimilarstackableArduinohardwareavailableinthemarket.For
example,https://www.kickstarter.com/projects/raspitv/raspio-duino-affordable-arduino-
programming-on-ras.
Engagethrusters
1. Oncethearchiveisdownloadedfromtheirwebpage,weextractthecontents:
tar–xvzfalamode-setup.tar.gz
2. Oncethefilesareextracted,thesetupisasfollows:
sudo./setup
3. Aftertheinstallationiscomplete,theRaspberryPialamode’sserialportis
enumeratedas/dev/ttyS0.
Objectivecomplete–minidebriefing
Aftertheinstallationiscomplete,weshouldhavetheRaspberryPiAlaModemode
enumeratedandbereadytostartprogrammingthehardwareadd-onboard.
TheWeasleyweatherclock
WewillbuildaWeasleyweatherclockinthisprojectusinganArduinomicrocontroller
boardandtheRaspberryPi.TheWeasleyWeatherclockisinspiredbytheWeasleyclock
seenintheHarryPotterseriesofmovies.AWeasleyclockisusedtoidentifythecurrent
locationofafamilymemberoftheWeasleys(forexample,work,school,andsoon)and
alsothesafetyofthefamilymember.Mrs.MollyWeasley(thematriarchoftheWeasleys)
usedtheWeasleyclocktokeeptabsonherfamilyandthisclockhashaditsvariantsover
theyears.Thisprojecthappenstobeoneofthem!
TheWeasleyweatherclockisonethatdisplaysthecurrentoutdoortemperatureandthe
forecast.Italsowarnsusaboutimpendingdangersduetoconditionssuchastornadoes,
blizzards,andsoon.
AWeasleyweatherclockbuiltusingtheArduinoandtheRaspberryPi
Prepareforliftoff
Thefollowingitems(alongwiththeirapproximatecost)arerequiredtobuildourWeasley
clock:
Item Price
RaspberryPimodelB*1 US$35
ArduinoUno/RaspberryPiAlaModemode(http://wyolum.com/projects/alamode/)*1 US$30/45
AcrylicSheet24inchesx20inches*0.093inchthick*1 US$10
Woodsheet1ftx1/2ftx0.25inchthick*1 US$5
5VDCSteppermotorfromAdafruit*1(http://www.adafruit.com/product/858) US$5
RGBLEDStrip1m*1(analogones(http://www.adafruit.com/products/1004)) US$15
NPNtransistors*2(BC547orNP2222) US$1
PowerDarlingtonStepperDriver(ULN2003A) US$2
Cablesforconnection US$4
7-SegmentBackpack(http://www.adafruit.com/product/879) US$10
A8x8LEDMatrixbackpack(optional(http://www.adafruit.com/product/871)) US$10
BlinkM(optional) US$13
12V,1ADCwalltransformer(optional(https://www.sparkfun.com/products/8579)) US$8
Totalcost US$122approx.
Engagethrusters
1. TheWeasleyclockcouldbeeasilyassembledwithpartsmachinedwithalasercutter.
Lasercuttingisaprocesswherepartsaremachined/engraved/cutusingahigh-
powerlaserbeaminacontrolledenvironment.
Thelasercutteriswidelyusedforprototypingpurposes.Thedesignfilesfor
lasercuttingareavailablealongwiththisbookcodebundle.
Inthisexample,thedialoftheweatherclockiscutfromtheacrylicandthe
designincludesmountingholesfortheclockaswellasthesteppermotor.
Theweatherkeywordsareengravedandmachinedusingwoodsheets.The
assemblyofthekeywordsandthedialareshowninthefollowingfigure:
PartialassemblyoftheWeasleyClock
Objectivecomplete–minidebriefing
Theassemblyshownintheimageissufficienttotestthisexample.Youcanaddmore
featurestothedesign.Forexample,youcanaddslotsontheacrylicboardtoembeda7-
Segmentdisplay,8x8LEDmatrix,oraBlinkMRGBLEDtothedesign.
Inthisexample,theArduinoisthelow-levelcontroller,whichdrivestheRGBLEDstrip,
steppermotor,andsoon,whiletheweatherdataisobtainedfromtheInternetusingthe
RaspberryPi.WewilldiscusstheArduinocodeinthefirstpartofourtask.
FlowofdataandcontrolinthisWeasleyClockproject
ControllingthestepperusingtheArduino
Thepartnumberofthesteppermotorusedinthisexampleis28BJY-48
(http://www.adafruit.com/product/858).Asteppermotorisatypeofmotorthatisoperated
byenergizingitscoilsinseveralsteps.Thecoilenergizationinseveralstepsenablesthe
steppertorotateinpreciseangularsteps.Thisprecisemovementaidstheuseofastepper
motorinopenloopsystems.Sincetheworkingprincipleofasteppermotorisbeyondthe
scopeofthebook,let’sdiscussitscontroltechnique.
Prepareforliftoff
Thesteppermotorispoweredbyacommonleadconnectedtothepowersupplyandthe
otherendisconnectedtoatransistor.Sincetransistorscanbeusedasswitches,theleads
ofthecoilcanbegroundedalternatively.Thisalternativesequencecausesthestepper
motortorotateandthespeedofrotationiscontrolledbyintroducingadelayinbetween
thecoilenergization.Theminimumdelayrequiredbetweeneachenergizationstepto
makethestepperrotateproperlyandavoidmissstepsis2milliseconds.Thisisduetothe
designlimitationsofthesteppermotor.
Thefollowingtableshowsthecoilenergizationsequenceforthesteppermotorina
clockwisedirection(borrowedfromthedatasheet).Theenergizationsequenceshownhere
wouldmakethestepperrotateinahalfstepperactuation,thatis,thestepperwouldrotate
2.8125degreesforeveryactuationsequence.
Note
Itisassumedthatyouarefamiliarwithsteppermotorsandtheircontroltheory.
Asteppermotorenergizationsequencefrom28BJY-48’sdatasheet
Engagethrusters
1. Eachcolumnintheprecedingdiagramindicatestheleadthatneedstobeenergizedto
rotateasinglestep.
2. Forexample,inthecaseofclockwiserotation,Lead4isenergizedandallotherleads
areturnedoff.Thedatasheetexplainsthatthesteppermotorrotatesapproximately
5.625degreesperstep.
3. Hence,64actuationstepsarerequired(64*5.626=360degrees)tomakeone
completerotation.Thesteppermotorisinterfacedtoagearboxof1:64ratio,and
eachrotationtakesabout4096steps.
4. Let’sreviewthecoderequiredfortheenergizationsequence(codeborrowedfromthe
Arduinoforumshttp://forum.arduino.cc/index.php?topic=85335.0):
//Step1
digitalWrite(motorPin4,HIGH);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
//Step2
digitalWrite(motorPin4,HIGH);
digitalWrite(motorPin3,HIGH);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
//Step3
digitalWrite(motorPin4,LOW);
digitalWrite(motorPin3,HIGH);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
//Step4
digitalWrite(motorPin4,LOW);
digitalWrite(motorPin3,HIGH);
digitalWrite(motorPin2,HIGH);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
//Step5
digitalWrite(motorPin4,LOW);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,HIGH);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
//Step6
digitalWrite(motorPin4,LOW);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,HIGH);
digitalWrite(motorPin1,HIGH);
delay(motorSpeed);
//Step7
digitalWrite(motorPin4,LOW);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,HIGH);delay(motorSpeed);
//Step8
digitalWrite(motorPin4,HIGH);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,HIGH);
delay(motorSpeed);
}
5. Let’sdiscussthefirststepinthesteppermotorenergizationsequence:
//Step1
digitalWrite(motorPin4,HIGH);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin1,LOW);
delay(motorSpeed);
6. Intheprecedinglinesofcode,themotorPin4pinissettoHigh,whiletheotherpins
aresettoLow.Asshowninthefollowingfigure,thepinsmotorPin1through
motorPin4areconnectedtoapowerDarlingtoncircuit.Youcanfindareferenceto
thePowerDarlingtoncircuitathttps://coefs.uncc.edu/dlsharer/files/2012/04/F5.pdf.
AnArduinosteppermotorinterface
7. Whenmotorpin4(theD11pinoftheArduinoisconnectedtothebasepinofthe
powerDarlingtonpair)issettohigh,thetransistor(whichactsaswitch)connectsthe
orangeleadtothegroundandenergizesthecoilandtherebythesteppermovesbya
singlestep.
8. Similarly,thesteppermotor’scoilsareenergizedinthesequenceshowninthetable.
Forexample,instep2,thecoils4and3areenergizedbysettingmotorPin4and
motorPin3toHighandotherpinstoLow.
Counterclockwiserotationofthesteppermotor
1. Thecounterclockwiserotationisachievedbyreversingtheorderofenergization.In
thefirststep,Lead1isenergized,whichisfollowedbyLeads1and2.Thetablefor
counterclockwiserotationisshownasfollows:
LeadWireColor
CCWDirection
12345678
1BLU - - 
2PIK ---
3YEL --- 
4ORG ---
2. Hence,thecodeforthefirststepwillbeasfollows:
digitalWrite(motorPin1,HIGH);
digitalWrite(motorPin2,LOW);
digitalWrite(motorPin3,LOW);
digitalWrite(motorPin4,LOW);
delay(motorSpeed);
Objectivecomplete–minidebriefing
Note
Ifyouarenotfamiliarwithsteppermotorsandtheircontroltechniques,thereareabundant
resourcesandonesuchresourceis
http://www.societyofrobots.com/member_tutorials/node/314.
WediscussedthesteppermotorcontroltechniqueusingtheArduinomicrocontroller.Once
wehavediscussedtheprerequisites,wewilltakethiscodesampleandbuildthingsaround
it.
ControllingtheRGBLEDStripusingthe
Arduino
WedepictthemoodoftheweatherforecastbyusingRGBLEDlighting.Weindicatecold
weatherindicationswithbluecolorlighting,fairweatherconditionswithgreenlighting,
andwarm/dangerousweatherconditionsusingredlighting.Inthissection,wewilllook
intocontrollinganRGBLEDusingtheArduino.
TheRGBLEDstripsoldbyAdafruitindustries(http://www.adafruit.com/products/1004)
consumesabout60mApersegment.ItisbestrecommendedtodrivetheRGBLEDstrip
usingatransistorswitchingcircuit.Weneedtousethreetransistorsforthethreecolors
anditispossibletocontroleachcolorindividuallyanditisalsopossibletoobtaina
combinationofcolours.
Note
ItispossibletoproduceasecondarycolorusingtheRGBcombinations.Thiscanbe
achievedbyturningontheRGBsegmentsatthesametimeandvaryingthebrightnessof
theprimarycolors.Therearevastresourcesavailableforsuchtipsandtricksonthe
Internetandanexplanationofthisisbeyondthescopeofthisbook.
Prepareforliftoff
TheAdafruitlearningwebsiteprovidesexamplesforcontrollingtheRGBLEDusinga
pulsewidthmodulationtechnique.TheschematicfortheAnalogRGBstripisshownin
thefollowingdiagram:
RGBLEDstripschematic(borrowedfromAdafruit)
SincetheRGBstriprequires12V,wemustuseatransistorswitchingcircuittocontrolthe
LEDs.ThetransistorswitchingcircuitforcontrollingtheRed,Green,andBluechannels
oftheLEDstripisshowninthefollowingdiagram:
TheArduinoRGBswitchingcircuit
TheRGBchannelsareconnectedtotheNPNtransistorsthatactasswitches.Thebaseof
thetransistorisconnectedtothePWM(PulseWidthModulation)outputoftheArduino.
ThisenablesyoutoadjustthebrightnessoftheRGBchannels,andconsequently,produce
differentcolors.
Engagethrusters
1. AdafruithasprovidedanexampleforadjustingthebrightnessoftheLEDsand
producingdifferentcolorsfromthecombinationofprimarycolors.Let’sconsiderthe
followingpieceofcode:
//fadefrombluetoviolet
for(r=0;r<256;r++){
analogWrite(REDPIN,r);
delay(FADESPEED);
}
//fadefromviolettored
for(b=255;b>0;b--){
analogWrite(BLUEPIN,b);
delay(FADESPEED);
}
2. Inthiscode,thered,greenandbluesegmentsoftheRGBLEDstripareconnectedto
theD3,D5,andD6oftheArduino,respectively.
ThevaluewrittentothepinsusingtheanalogWritefunctionsetsthebrightness
valueofeachcolor.
TheanalogWritefunctionvariesthedutycycleofthePWMchanneland
acceptsvaluesbetween0and255.
Thevalue0indicatesa0percentdutycycleand255indicatesa100percent
dutycycle.ThedutycycledeterminesthecurrentthatflowsthroughtheLED,
andinturn,controlsthebrightnessandcolor.
Objectivecomplete–minidebriefing
WediscussedadjustingthebrightnessoftheRGBLEDstripusingthePulseWidth
ModulationTechniqueandanArduinomicrocontroller-baseddevelopmentplatform.
I2CCommunicationusingtheArduino
(optional)
Inthisproject,thereisa7-Segmentdisplay,8x8LEDmatrix,proximitysensor(to
determinethehomeposition),andaBlinkMRGBLEDthatcommunicatesviatheI2C
interface.Wewilldiscusstheapplicationofeachcomponentinthisproject.
Prepareforliftoff
ThemainrequirementforthissectionisthenecessaryI2Cdevicerequiredtointerface
withtheweatherclock.
Engagethrusters
Letusreviewaboutthe7-Segmentdisplay.
The7-Segmentdisplay
1. TheAdafruit7-Segmentdisplaybackpack(reference:thetutorialavailableat
https://learn.adafruit.com/adafruit-led-backpack/0-dot-56-seven-segment-backpack
providesinstructionsonsettingupthebackpackandtestingthebackpackwithacode
sample),whichisusedtodisplaythecurrentatmospherictemperatureobtainedvia
theRaspberryPi.
2. Adafruitprovideslibrariestowritetothe7-Segmentdisplay.Inordertowritetothe
7-Segmentdisplay,wedeclarea7-Segmentobject:
Adafruit_7segmentmatrix_7segment=Adafruit_7segment();
WeinitializetheI2CportaddressofthedeviceintheArduinosetup()function:
matrix_7segment.begin(0x70);
Now,wecancalltheobjectandwritedataonthedisplay(codeborrowedfrom
AdafruitLEDbackpacklibraries):
matrix_7segment.clear();
matrix_7segment.print(temp,DEC);
matrix_7segment.writeDisplay();
8x8LEDmatrix
1. TheAdafruit8x8matrixisusedtodisplaythemoodofthecurrentweathercondition
usingasmiley.(Thesetuptutorialcanbefoundathttps://learn.adafruit.com/adafruit-
led-backpack/0-8-8x8-matrix).
2. Ifthecurrentweatherconditionisfair,asmileisdisplayedandafrownisdisplayed
forimpendingdanger.
3. Thewriteprocessissimilartothe7-Segmentdisplay.The7-Segmentdisplayandthe
8x8displaymatrixusetheMAX7219chip.Hence,itisnecessarytouseadifferent
addressfortheLEDmatrix.TheAdafruittutorial(https://learn.adafruit.com/adafruit-
led-backpack/connecting-multiple-backpacks)clearlyexplainshowtochangeI2C
portaddressesontheLEDbackpack.Youarewelcometoswitchtheaddressifboth
the7-SegmentdisplayandtheLEDmatrixarebeingusedintheproject.
4. Itisalsopossibletowritestringstothe8x8matrixandscrolllikeamarquee.Similar
tothe7-Segmentdisplay,wewillinitializetheobjecttocommunicatewiththeLED
matrix:
Adafruit_8x8matrixmatrix=Adafruit_8x8matrix();
WeinitializetheI2CportaddressofthedeviceintheArduinosetup()function:
matrix_7segment.begin(0x73);
Adafruittutorialsalsoexplainthecreationofbitmapsforthesmileystobe
displayed:
staticuint8_t__attribute__((progmem))smile_bmp[]={0x3C,0x42,
0x95,0xA1,0xA1,0x95,0x42,0x3C};
staticuint8_t__attribute__((progmem))frown_bmp[]={0x3C,0x42,
0xA5,0x91,0x91,0xA5,0x42,0x3C};
staticuint8_t__attribute__((progmem))neutral_bmp[]={0x3C,0x42,
0x95,0x91,0x91,0x95,0x42,0x3C}
ThebitmapisusedtodeterminetheLEDsthatwouldhavetobeturnedonto
createthesmiley.Forexample,0x3C(binaryvalue:00111100)turnsonthe
LEDsexceptforthefirstandlasttwooneitherends:
matrix.clear();
matrix.setRotation(3);
matrix.drawBitmap(0,0,smile_bmp,8,8,LED_ON);
matrix.writeDisplay();
ThesetRotationfunctionisusedtorotatethedisplayimageby90degrees.
ThedrawBitmapfunctionisusedtodrawthebitmaponthedisplay.Inthe
drawBitmapfunction,thefirsttwoargumentsspecifythexandyofthestarting
positionfollowedbythebitmap,width,heightofthebitmap,anditscolor.
BlinkM
1. WediscussedtheBlinkMRGBLEDinProject2,ARaspberryWebIDEExample.
TheBlinkMisusedtoindicateimpendingdangerbyflashingaredcolorintheevent
ofimpendingdanger.WeusetheBlinkMlibrariestoplayaflashingredscriptinsuch
scenarios:
BlinkM_playScript(script_no,0,0);
2. TheBlinkM_playScriptfunctiontakesthescriptnumberoftheRGBLED.The
secondargumentisthenumberofrepeatsforthescript.Whenthethirdargumentis
zero,thescriptisplayedinaninfiniteloop.
Proximitysensor
1. Theproximitysensorisusedtodeterminethehomepositionofthearrowthatisused
topointtotheweatherposition.Theproximitysensorusedinthisprojectisthe
OSEPPProximitySensorModulefromParallax.Theproximitysensordetectsthe
presenceofobjectsandcommunicatesthisviatheI2Ccommunicationport.
2. SimilartotheotherI2Cdevices,wesetthesensoraddressasfollows:
constuint8_tsensorAddr=0x20;
WeturnonthesensorintheArduinosetup()method:
WriteByte(sensorAddr,0x3,0xFE);
Thesensor’sreadingisreadby:
ReadByte(sensorAddr,0x0,&val)
Objectivecomplete–minidebriefing
WediscussedtheinterfacingofdifferentI2Cdevicesthatcouldbeusedinthisproject.In
thenextsection,wewillworkoncontrollingthesedevicesusinganindividualcontrol
signal.
Serialportcommunicationwiththe
RaspberryPi
Asmentionedearlier,theweatherdataisobtainedbytheRaspberryPiandcommunicates
thedatawithcontrolcharactersviatheserialport.Wewilldiscussthecontrolsignalsused
inthisproject.
Engagethrusters
Let’sgetstartedbyreviewingthePythonscriptusedtooperatetheweatherdisplay.
PythonprogramfortheWeasleyclock
1. Inthissection,wewilldiscussthePythoncodefortheweatherclock.Theimportant
requirementforthisprojectisthePythonweatherAPI.Weneedtodownloadand
installittogetstarted.IfsubversionisnotinstalledontheRaspberryPi,itcanbe
installedusingthefollowingcommand:
sudoapt-getinstallsubversion
2. Oncetheinstallationiscomplete,thePythonweatherAPIrepositorycanbeclonedas
follows:
svncheckouthttp://python-weather-api.googlecode.com/svn/trunk/
python-weather-api-read-only
3. ThePythonweatherAPIhasaPython3requirementandisinstalledasfollows:
cdpython-weather-api-read-only
python3setup.pybuild
python3setup.pyinstall
4. Let’sreviewthePythonscriptusedtooperatetheweatherdisplay.Wewillimportthe
serialport,pywapi,andtime(fordelay)modulesfortheproject:
#!/usr/bin/envpython
importserial
importglob
importpprint
importpywapi
fromtimeimportsleep
Wewilldetermineandestablishconnectiontotheserialport.Thescan()
functionidentifiesalltheserialportsavailableontheRaspberryPi:
#Establishserialportcommunication
defscan():
returnglob.glob('/dev/ttyS*')+glob.glob('/dev/ttyUSB*')+
glob.glob('/dev/ttyACM*')
sport_data=scan()
fornameinscan():
serialport=serial.Serial(name,9600)
sleep(5)
serialport.write(bytes("A",'ascii'))
sleep(1)
response=serialport.read()
if(response==b'A'):
sport=name
serialport.close()
break
seport=serial.Serial(sport,9600,timeout=45)
5. Oncetheserialportshavebeenidentified,wetestthembysendingabyteAandawait
aresponse.WhenaresponsewiththebyteAisreceived,weidentifyandsavethe
serialport.Afteridentification,wewillestablishaconnectionwiththeArduino.
6. Inthisproject,weareusingtheNOAAwebsitetoobtaintheweatherdata.Wehave
toidentifythecity’sweathercodetoobtainthecurrentlocation’sweatherstation
code.Thiscouldbesimplyobtainedbyenteringthezipcodeontheirwebsite.For
example,theweatherstationcodeforChicagoisKORD.
WeatherstationforChicago,IL
Theweatherdataisobtainedasfollows:
result=pywapi.get_weather_from_noaa('KORD')
Thetemperaturedataisretrievedasfollows:
temperature=int(float(result['temp_f']))
Theretrieveddataiswrittentotheserialport:
temperature_string="S"+str(temperature)
#print(temperature_string)
seport.write(bytes(temperature_string,'ascii'))
Basedonthetemperaturedata,theRGBstrip,BlinkMcontroldata,and8x8
matrixdataarewrittentotheArduino:
if(temperature>40):
seport.write(bytes("G",'ascii'))
sleep(5)
seport.write(bytes("P4",'ascii'))
sleep(5)
seport.write(bytes("M1",'ascii'))
sleep(5)
Wewillsettheweatherclocktopointataweatherforecastbasedonthedata
obtained:
if(result['weather']=='LightSnow')or(result['weather']=='Snow')
or(result['weather']=='Flurries'):
seport.write(bytes("H",'ascii'))
sleep(5)
seport.write(bytes("T-2",'ascii'))
sleep(5)
7. Let’sreviewthecodeforthecontrolfromtheRaspberryPiandthecorresponding
acknowledgmentsignals.
Arduinoacknowledgementtocontrolsignal
Letusreviewonthecontrolsignalandcontrolflowoftheweatherclock.
Controlflowfortheweatherclock
ThefollowingflowchartshowswhathappensintheArduinowhenacontrolcharacteris
receivedfromtheRaspberryPi.
Theweatherclockprogramflow
1. TheRaspberryPitriestoidentifytheArduinobysendingacharacterA.TheArduino
respondswithanacknowledgementcharacterA:
if(serial_read=='A'){
Serial.print("A");
}
2. Thisisafoolproofmechanismtoidentifyandestablishacommunicationwiththe
weatherclockcontrollerfromtheRaspberryPi.
Temperaturedata
1. TheRaspberryPitemperaturedataissenttotheArduinowiththeletter/characterS.
Thereceiveddataisconvertedtoasignedintegerandpassedasanargumenttothe7-
Segmentdisplaylibraries:
if(serial_read=='S'){
while(Serial.available()){
sb=Serial.read();
sevenseg_string[serInIndx]=sb;
serInIndx++;
temp=0;
}
temp=atoi(sevenseg_string);
memset(sevenseg_string,0,9);
}
2. WhenthecharacterSisreceived,wereadallthecharactersintothebuffer
sevenseg_string.Thestringisconvertedtoanintegerusingtheatoifunctionand
storedinthetempvariable.Thebufferisclearedattheendofthecycle.Thismethod
takessub-zerotemperaturesintoconsideration.
ControloftheRGBLEDstrip
1. TheindividualcolorsoftheRGBLEDarecontrolledindividuallyusingtheASCII
charactersR,G,and,Brespectively.Eachcolorindicatesauniqueweathercondition,
namely,blueindicatescoldweather,greenindicatesfairweatherconditions,andred
colorindicatesimpedingdangerinweatherconditions:
if(serial_read=='R'||serial_read=='G'||
serial_read=='B'){
color_bit=serial_read;
}
if(color_bit=='R'){
lightsequence_red();
}
elseif(color_bit=='G'){
lightsequence_green();
}
elseif(color_bit=='B'){
lightsequence_blue();
}
2. Whenthecharacterisreceived,thecorrespondinglightsequenceisturnedon.
Controlofstepperviaserialport
1. Earlier,wediscussedthecontrolofthesteppermotorusingapowerDarlington
driverandthecontrolroutineforonefullrotation.Inthissection,wewilldiscuss
howtocontrolthedirectionandthenumberofstepsbasedontheinputfromthe
serialport.Inthisexample,theclockwisedirectionisindicatedby+,and
counterclockwisedirectionisindicatedby-.
Forexample,inordertomove45stepsinaclockwisedirection,thecommand
wouldbe+45precededbytheletterP.Hence,itwouldbeP+45.Similarly,the
counterclockwisedirectioncommandwouldbeP-45:
if(serial_read=='P'){
while(Serial.available())
{
sb=Serial.read();
serInString[serInIndx]=sb;
serInIndx++;
}
}
2. WeawaittheserialcharacterPandstoretherestofthestringinabuffer.Oncethe
dataisstoredinthebuffer,wewilldeterminewhetherthefirstcharacteris+or-.
TheASCIInumberforthe+signis43and45forthe-sign.Wecomparethe
firstcharacterinthebufferandexecutethecommandaccordingly.Serial
communicationsusuallytransmitASCIInumbersandhencethenumbersare
convertedintotheirdecimalequivalents:
if(serInString[0]==43){
intvar_serial=0;
for(serOutIndx=1;serOutIndx<serInIndx;serOutIndx++)
{
var_serial=var_serial*10+(serInString[serOutIndx]-48);
}
motorSpeed=20;
for(inti=0;i<var_serial;i++){
clockwise();

}
Weconvertthereceivedserialdataintotheirdecimalequivalentatthisstep:
var_serial=var_serial*10+(serInString[serOutIndx]-48);
Onceconverted,wemovethestepperforthedesirednumberofstepsineither
directionusingtheclockwise()andcounterclockwise()functions.
3. Wewantthesteppermotortoreachthehomepositioneverytimebeforepointingtoa
particularweathercondition.Thissystemisanopenloopandsoitisnecessaryto
movethearrowtothehomepositionbeforepointingtothecurrentweather
condition.
Note
Thesteppermotormovesinacounterclockwisedirectiontopointatallweather
conditionsandaclockwisedirectiontomovetowardsthehomeposition.
4. Hence,whentheletterHistransmittedviatheserialport,thearrowismovedtowards
thehomeposition:
if(serial_read=='H'){
reset_stepper();
lightsequence();
}
Thereset_stepper()functiontakescareofsettingthearrowtothehome
position:
voidreset_stepper(void){
uint8_tval;
//Getthevaluefromthesensor
if(ReadByte(sensorAddr,0x0,&val)==0)
{
//ThesecondLSBindicatesifsomethingwasnotdetected,
i.e.,
//LO=objectdetected,HI=nothingdetected
while(val&0x2)
{
motorSpeed=20;
Serial.println("Nothingdetected");
if(ReadByte(sensorAddr,0x0,&val)==0){
clockwise();//Wekeepgoingclockwiseuntilthearrowis
detected
}
}

}
else
{
Serial.println("Failedtoreadfromsensor");
}
}
Inthereset_stepper()function,wewillexecutethesteppermotor’sclockwise
routineuntiltheobjectisdetected.Thesensorreferencemanualmentionsthat
anobjectisdetectedifthesecondLSBissettolow.Hence,thestepperrotates
intheclockwisedirectionuntilalowsignalisdetected.
Programmingtheweatherforecastposition
1. Intheprevioussection,wediscussedthesteppermotorcontrolviatheserialport.
Sinceweareusingasteppermotor,itispossibletopointateachweatherforecast
conditionbasedonapredeterminednumberofstepsfromthestep.So,wewill
determinethenumberofstepsrequiredtopointateachweatherforecastcondition
andprogramthesepositionsintotheflashmemoryoftheArduino.
WeshouldusethePROGMEMkeywordtostorethepositiondataintheflash
memoryoftheArduinosincetheyareaconstant:
constintmydata[6][2]PROGMEM={
1,10,
2,18,
3,28,
4,43,
5,54,
6,66};
Thenumbers1through6inthearraycorrespondtotheweatherforecast
indicatorsstartinginthecounterclockwisedirection.Thesecondposition
indicatesthenumberofpositionsfromthehomepositiontopointtothat
particularweathercondition.
ThecommandforindicatingweatherdataisprecededbytheletterT.Inorderto
pointtotheweatherforecast,Rain,thecommandwouldbeT-6.Whena
characterTisreceived,westorethedatareceivedinabuffer.Itisconfirmedthat
thesecondcharacterreceivedaftertheletterTisanumberbetween1and6.We
willretrievethecorrespondingpositiondatafromtheflashmemoryusingthe
pgm_read_word_near()function.Oncethedataisretrieved,thesteppermotor
controlroutineisexecutedforthedesirednumberofsteps.
Nowwewillretrievethedatafromtheflashmemoryasfollows:
if(serial_read=='T'){
while(Serial.available())
{
sb=Serial.read();
serInString[serInIndx]=sb;
serInIndx++;
}
}
intvar_serial=serInString[1]-48;
serInIndx=0;
if(var_serial>0&&var_serial<=6)
{
steps=pgm_read_word_near(&mydata[(var_serial-1)][1]);
Serial.println(steps);
}
if(serInString[0]==45){

motorSpeed=20;
for(inti=0;i<steps;i++){
counterclockwise();
}
8x8matrixcontrol
WewillcontroltheLEDmatrixusingtheletterM.AsmileisdisplayedifM1is
receivedandafrownifM2isreceived:
if(serial_read=='M'){
sb=Serial.read();
if(sb-'0'==1){
set_display(smile_bmp);
}
elseif(sb-'0'==2){
set_display(frown_bmp);
}
}
BlinkMcontrol
TheBlinkMscriptisplayedwhenevertheletterPisreceived.TheletterPisfollowed
bythescriptnumber.
if(serial_read=='P'){
while(Serial.available())
{
sb=Serial.read();
serInString[serInIndx]=sb;
serInIndx++;
}
BlinkM_playScript(BlinkM_addr,serInString[0]-48,0,0);
}
Objectivecomplete–minidebriefing
Inthissection,wediscussedtheoverallcontroloftheweatherclockanditsinterfaceto
theInternet.Wealsodiscussedtheinterfacingofthesensorsanddisplayingtheweather
data.
Missionaccomplished
Inthisproject,wediscussedinterfacinganArduinowiththeRaspberryPi.Thiswas
followedbyanexampleofconstructingaweatherclock.WedemonstratedtheArduinoas
alow-levelcontrollerthatinterfacesactuators,sensors,anddisplaydeviceswhilethe
RaspberryPiisinterfacedwiththeInternet.Ihopeyouenjoyedtheproject!
Hotshotchallenge
Inthisexample,thecitylocationwashard-codedintothePythonscript.Itispossibleto
displaytheweatherdatabasedonthezipcode/citylocation.Whatcouldtheinputdevice
be?Howcanthisbeachieved?
Chapter4.ChristmasLightSequencer
Asthenamesuggests,wewilldesignautomationandcontrolofChristmaslightsinour
homes.Wewilldecorateourhomeswithlightsforanyfestiveoccasionandworkona
projectthatenablesustobuildfantasticprojects.Wewillbuildalocalservertocontrol
thedevices.Wewillusetheweb.pyframeworktodesignthewebserver.We’dliketo
dedicatethischaptertothememoryofAaronSwartzwhowasthefounderoftheweb.py
framework.
Missionbriefing
Inthischapter,wewillinstallalocalwebserver-basedcontrolofGPIOpinsonthe
RaspberryPi.Wewillusethiswebserverframeworktocontrolitviaawebpage.
TheRaspberryPiontopofthetreeisjustanornamentfordecoration
Whyisitawesome?
Wecelebratefestiveoccasionsbydecoratingourhomes.Thedecorationsreflectourheart
anditcanbeenhancedbyusingRaspberryPi.
Note
ThisprojectinvolvesinterfacingAC-powereddevicestoRaspberryPi.Youshould
exerciseextremecautionwhileinterfacingthedevices,anditisstronglyrecommended
thatyousticktotherecommendeddevices.
Yourobjectives
Inthischapter,wewillworkonthefollowingaspects:
InterfaceoftheChristmastreelightsandotherdecorativeequipmenttothe
RaspberryPi
Setupthedigitally-addressableRGBmatrix
Interfaceofanaudiodevice
Settingupthewebserver
Interfacingdevicestothewebserver
Missionchecklist
Thischapterisbasedonabroadconcept.Youarefreetochoosedecorativeitemsofyour
owninterest.Wechosetoshowthefollowingitemsfordemonstration:
Item EstimatedCost
Christmastree*1 30USD
Outdoordecoration(optional) 30USD
SantaClausfigurine*1 20USD
Digitallyaddressablestrip*1 30USDapproximately
PowerSwitchTail2fromAdafruitIndustries(http://www.adafruit.com/product/268) 25USDapproximately
ArduinoUno(anyvariant) 20–30USDapproximately
InterfacethedevicestotheRaspberryPi
Note
ItisimportanttoexercisecautionwhileconnectingelectricalappliancestotheRaspberry
Pi.Ifyoudon’tknowwhatyouaredoing,pleaseskipthissection.Adultsupervisionis
requiredwhileconnectingappliances.
Inthistask,wewilllookintointerfacingdecorativeappliances(operatedwithanAC
powersupply)suchastheChristmastree.ItisimportanttointerfaceACappliancestothe
RaspberryPiinaccordancewithsafetypractices.ItispossibletoconnectACappliances
totheRaspberryPiusingsolidstaterelays.However,iftheprototypeboardsaren’t
connectedproperly,itisapotentialhazard.Hence,weusethePowerSwitchTailIIsold
byAdafruitIndustries.
Note
ThePowerSwitchTailIIhasbeenratedfor110V.
AccordingtothespecificationsprovidedontheAdafruitwebsite,PowerSwitchTail’s
relaycanswitchupto15Aresistiveloads.Itcanbecontrolledbyprovidinga3-12VDC
signal.WewilllookintocontrollingthelightsonaChristmastreeinthistask.
PowerSwitchTailII–imagesource:Adafruit.com
Prepareforliftoff
WehavetoconnectthePowerSwitchTailIItotheRaspberryPitotestit.Thefollow
FritzingschematicshowstheconnectionoftheswitchtotheRaspberryPiusingPi
Cobbler.Pin25isconnectedtoin+,whilethein-pinisconnectedtotheGroundpinof
theRaspberryPi.
TheRaspberryPiconnectiontothePowerSwitchTailIIusingPiCobbler
ThePiCobblerbreakoutboardisconnectedtotheRaspberryPiasshowninthefollowing
image:
Engagethrusters
1. Inordertotestthedevice,therearetwooptionstocontrolthedevicetheGPIOPins
oftheRaspberryPi.Thiscanbecontrolledeitherusingthequick2wireGPIOlibrary
orusingtheRaspiGPIOlibrary.
Note
Themaindifferencebetweenthequick2wiregpiolibraryandtheRaspiGPIOlibrary
isthattheformerdoesnotrequirethatthePythonscripttoberunwithrootuser
privileges(tothosewhoarenotfamiliarwithrootprivileges,thePythonscriptneeds
toberunusingsudo).InthecaseoftheRaspiGPIOlibrary,itispossibletosetthe
ownershipofthepinstoavoidexecutingthescriptasroot.Thisisleftassome
homeworkforyou.
2. Oncetheinstallationiscomplete,let’sturnon/offthelightsonthetreewithathree
secondinterval.Thecodeforitisgivenasfollows:
#Importtherpi.gpiomodule.
importRPi.GPIOasGPIO
#Importdelaymodule.
fromtimeimportsleep
#SettoBCMGPIO
GPIO.setmode(GPIO.BCM)
#BCMpin25istheoutput.
GPIO.setup(25,GPIO.OUT)
#InitialisePin25tolow(false)sothattheChristmastreelightsare
switchedoff.
GPIO.output(25,False)
while1:
GPIO.output(25,False)
sleep(3)
GPIO.output(25,True)
sleep(3)
Intheprecedingexample,wewillgetstartedbyimportingtheraspi.gpio
moduleandthetimemoduletointroduceadelaybetweenturningon/offthe
lights:
importRPi.GPIOasGPIO
#Importdelaymodule
fromtimeimportsleep
WeneedtosetthemodeinwhichtheGPIOpinsarebeingused.Therearetwo
modes,namelytheboard’sGPIOmodeandtheBCMGPIOmode(more
informationavailableonhttp://sourceforge.net/p/raspberry-gpio-python/wiki/).
TheformerreferstothepinnumbersontheRaspberryPiboardwhilethelatter
referstothepinnumberfoundontheBroadcomchipset.Inthisexample,we
willadopttheBCMchipset’spindescription.
Wewillsetthepin25tobeanoutputpinandsetittofalsesothatthe
Christmastreelightsareswitchedoffatthestartoftheprogram:
GPIO.setup(25,GPIO.OUT)
GPIO.output(25,False)
Intheprecedingroutine,weareswitchingoffthelightsandturningthemback
onwithathree-secondinterval:
while1:
GPIO.output(25,True)
sleep(3)
GPIO.output(25,False)
sleep(3)
3. Whenthepin25issettohigh,thedeviceisturnedon,anditisturnedoffwhenthe
pinissettolowwithathree-secondinterval.
ConnectingmultipleappliancestotheRaspberryPi
Let’sconsiderascenariowherewehavetocontrolmultipleappliancesusingthe
RaspberryPi.
Itispossibletoconnectamaximumof15devicestotheGPIOinterfaceoftheRaspberry
Pi.(Thereare17GPIOpinsontheRaspberryPiModelB,buttwoofthosepins,namely
GPIO14and15,aresettobeUARTinthedefaultstate.Thiscanbechangedafterstartup.
ItisalsopossibletoconnectaGPIOexpandertoconnectmoredevicestoRaspberryPi.)
Inthecaseofappliancesthatneedtobeconnectedtothe110VACmains,itis
recommendedthatyouusemultiplepowerswitchtailstoadheretosafetypractices.
Inthecaseofdecorativelightsthatoperateusingabattery(forexample,atwo-feet
Christmastree)orappliancesthatoperateatlowvoltagelevelsof12VDC,asimple
transistorcircuitandarelaycanbeusedtoconnectthedevices.Asamplecircuitisshown
inthefigurethatfollows:
Atransistorswitchingcircuit
Intheprecedingcircuit,sincetheGPIOpinsoperateat3.3Vlevels,wewillconnectthe
GPIOpintothebaseoftheNPNtransistor.Thecollectorpinofthetransistorisconnected
tooneendoftherelay.
ThetransistoractsasaswitchandwhentheGPIOpinissettohigh,thecollectoris
connectedtotheemitter(whichinturnisconnectedtotheground)andhence,energizes
therelay.
Relaysusuallyhavethreeterminals,namely,thecommonterminal,NormallyOpen
Terminal,andNormallyClosedTerminal.Whentherelayisnotenergized,thecommon
terminalisconnectedtotheNormallyClosedTerminal.Uponenergization,theNormally
OpenTerminalisconnectedtothecommonterminal,thusturningontheappliance.
Thefreewheelingdiodeacrosstherelayisusedtoprotectthecircuitfromanyreverse
currentfromtheswitchingoftherelays.
Thetransistorswitchingcircuitaidsinoperatinganappliancethatoperatesat12VDC
usingtheRaspberryPi’sGPIOpins(theGPIOpinsoftheRaspberryPioperateat3.3V
levels).Therelayandthetransistorswitchingcircuitenablescontrollinghighcurrent
devicesusingtheRaspberryPi.
Itispossibletouseanarrayofrelays(asshowninthefollowingimage)andcontrolan
arrayofdecorativelightingarrangements.Itwouldbecooltocontrollighting
arrangementsaccordingtothemusicthatisbeingplayedontheRaspberryPi(aproject
ideafortheholidays!).
Therelayboard(again,showninthefollowingimage)operatesat5VDCandcomeswith
thecircuitrydescribedearlierinthissection.Wecanmakeuseoftheboardbypowering
uptheboardusinga5VpowersupplyandconnectingtheGPIOpinstothepins
highlightedinred.Asexplainedearlier,therelaycanbeenergizedbysettingtheGPIOpin
tohigh.
Arelayboard
Objectivecomplete–minidebriefing
Inthissection,wediscussedcontrollingdecorativelightsandotherholidayappliancesby
runningaPythonscriptontheRaspberryPi.Let’smoveontothenextsectiontosetup
thedigitallyaddressableRGBLEDstrip!
SettingupthedigitallyaddressableRGB
matrix
Inthissection,wewilltalkaboutsettingupoptionsavailableforLEDlighting.Wewill
discusstwotypesofLEDstrips,namelyanalogRGBLEDstripsanddigitally-addressable
RGBLEDstrips.
Aswediscussedthefirstoneindetailinthepreviouschapter,wewillskipitandmoveon
tothesecondkind.AsampleofthedigitallyaddressableRGBLEDstripisshowninthe
imagethatfollows:
Prepareforliftoff
Asthenameexplains,digitally-addressableRGBLEDstripsarethosewherethecolourof
eachRGBLEDcanbeindividuallycontrolled(inthecaseoftheanalogstrip,thecolours
cannotbeindividuallycontrolled).
WherecanIbuythem?
TherearedifferentmodelsofthedigitallyaddressableRGBLEDstripsbasedondifferent
chipssuchasLPD6803,LPD8806,andWS2811.Thestripsaresoldinareelofa
maximumlengthof5meters.SomesourcestobuytheLEDstripsincludeAdafruit
(http://www.adafruit.com/product/306)andBanggood(http://www.banggood.com/5M-
5050-RGB-Dream-Color-6803-IC-LED-Strip-Light-Waterproof-IP67-12V-DC-p-
931386.html)andtheycostabout50USDforareel.Somevendors(includingAdafruit)
selltheminstripsofonemeteraswell.
Engagethrusters
Let’sreviewhowtocontrolandusethesedigitally-addressableRGBLEDstrips.
Howdoesitwork?
MostdigitallyaddressableRGBstripscomewithterminalstopoweringtheLEDs,aclock
pin,andadatapin.TheLEDsareseriallyconnectedtoeachotherandarecontrolled
throughtheSPI(SerialPeripheralInterface).
TheRGBLEDsonthestriparecontrolledbyachipthatlatchesdatafromthe
microcontroller/RaspberryPiontotheLEDswithreferencetotheclockcyclesreceivedon
theclockpin.
InthecaseoftheLPD8806strip,eachchipcancontrolabout2LEDs.Itcancontroleach
channeloftheRGBLEDusingaseven-bitPWMchannel.Moreinformationonthe
functionoftheRGBLEDstripisavailableathttps://learn.adafruit.com/digital-led-strip.
ItispossibletobreaktheLEDstripintoindividualsegments.Eachsegmentcontains
about2LEDs,andAdafruitindustrieshasprovidedanexcellenttutorialtoseparatethe
individualsegmentsoftheLEDstrip(https://learn.adafruit.com/digital-led-
strip/advanced-separating-strips).
LightinguptheRGBLEDstrip
TherearetwowaysofconnectingtheRGBLEDstrip.Theycaneitherbeconnectedtoan
ArduinoandcontrolledbytheRaspberryPiorcontrolledbytheRaspberryPidirectly.
AnArduino-basedcontrol
Note
Itisassumedthatyouarefamiliarwithprogrammingmicrocontrollers,especiallythoseon
theArduinoplatform.
InProject3,TheArduinoRaspberryPiInterface,wediscussedconnectingananalog
RGBstripusinganArduino.Weusedcontrolcommandstochangethecolorofthestrip
throughtheserialportofArduino.Similarly,wecanconnecttheRGBstriptothe
Arduino.
AnArduinoconnectiontothedigitallyaddressableinterface
Intheprecedingfigure,theLEDstripispoweredbyanexternalpowersupply.(Thetiny
greenadapterrepresentstheexternalpowersupply.Therecommendedpowersupplyfor
theRGBLEDstripis5V/2ApermeterofLEDs(whilewritingthischapter,wegotanold
computerpowersupplytopoweruptheLEDs).TheClockpins(theCIpin)andtheData
pins(DI)ofthefirstsegmentoftheRGBstripareconnectedtothepinsD2andD3
respectively.(WearedoingthissincewewilltesttheexamplefromAdafruitindustries.
Theexampleisavailableathttps://github.com/adafruit/LPD8806/tree/master/examples.)
SincetheRGBstripconsistsofmultiplesegmentsthatareseriallyconnected,theClock
Out(CO)andDataOut(DO)pinsofthefirstsegmentareconnectedtotheClockIn(CI)
andDataIn(DI)pinsofthesecondsegmentandsoon.
Let’sreviewtheexample,strandtest.pde,totesttheRGBLEDstrip.Theexample
makesuseofSoftwareSPI(BitBangingoftheclockanddatapinsforlightingeffects).It
isalsopossibletousetheSPIinterfaceoftheArduinoplatform.(Refertothisbook’s
websiteforanexample.)
Intheexample,weneedtosetthenumberofLEDsusedforthetest.Forexample,we
needtosetthenumberofLEDsonthestripto64foratwo-meterstrip.Hereishowtodo
this:
1. Thefollowinglineneedstobechanged:
intnLEDs=64;
2. Oncethecodeisuploaded,theRGBmatrixshouldlightup,asshowninthisimage:
8x8RGBmatrixlitup
3. Let’squicklyreviewtheArduinosketchfromAdafruit.Wewillgetstartedbysetting
upanLPD8806objectasfollows:
//nLEDSrefertonumberofLEDsinthestrip.Thiscannotexceed160
LEDs/5mduetocurrentdraw.
LPD8806strip=LPD8806(nLEDs,dataPin,clockPin);
4. Inthesetup()sectionoftheArduinosketch,wewillinitializetheRGBstripas
follows:
//StartuptheLEDstrip
strip.begin();
//Updatethestrip,tostarttheyareall'off'
strip.show();
5. Assoonasweenterthemainloop,scriptssuchascolorChaseandrainboware
executed.
6. WecanmakeuseofthisArduinosketchtoimplementserialportcommandsto
controlthelightingscriptsusingtheRaspberryPi.
Note
ThistaskmerelyprovidessomeideasofconnectingandlightinguptheRGBLED
strip.YoushouldfamiliarizeyourselfwiththeworkingprinciplesoftheRGBLED
strip.
ThereareseveralexamplesavailableforcontrollingtheLEDstripusingtheArduino
platform.Afewareavailableonthewebsiteofthisbook.
Note
TheRaspberryPihasanSPIport,andhence,itispossibletocontroltheRGBstrip
directlyfromtheRaspberryPi.Refertothisbook’swebsiteforsomeexamples.
Objectivecomplete–minidebriefing
Inthissection,wereviewedoptionsfordecorativelightingandcontrollingthemusingthe
RaspberryPiandArduino.
Interfaceofanaudiodevice
Inthistask,wewillworkoninstallingMP3andWAVfileaudioplayertoolsontheRaspbian
operatingsystem.
Prepareforliftoff
TheRaspberryPiisequippedwitha3.5mmaudiojackandthespeakerscanbeconnected
tothatoutput.Inordertogetstarted,weinstalltheALSAutilitiespackageanda
command-linemp3player:
sudoapt-getinstallalsa-utils
sudoapt-getinstallmpg321
Engagethrusters
Inordertousethealsa-utilsormpg321players,wehavetoactivatetheBCM2835’s
sounddriversandthiscanbedoneusingthemodprobecommand:
sudomodprobesnd_bcm2835
Afteractivatingthedrivers,itispossibletoplaytheWAVfilesusingtheaplaycommand
(aplayisacommand-lineplayeravailableaspartofthealsa-utilspackage):
aplaytestfile.wav
AnMP3filecanbeplayedusingthempg321command(acommand-lineMP3player):
mpg321testfile.mp3
Note
Intheprecedingexamples,thecommandswereexecutedinthedirectorywheretheWAV
fileortheMP3filewaslocated.IntheLinuxenvironment,itispossibletostopplayinga
filebypressingCTRL+C.
Objectivecomplete–minidebriefing
Wewereabletoinstallsoundutilitiesinthissection.Later,wewillusetheinstalled
utilitiestoplayaudiofromawebpage.
ItispossibletoplaythesoundfilesontheRaspberryPiusingthemoduleavailablein
Python.Someexamplesinclude:Snacksoundtoolkit,Pygame,andsoon.
Installingthewebserver
Inthissection,wewillinstallalocalwebserveronRaspberryPi.Therearedifferentweb
serverframeworksthatcanbeinstalledontheRaspberryPi.TheyincludeApachev2.0,
Boost,theRESTframework,andsoon.
Prepareforliftoff
Asmentionedearlier,wewillbuildawebserverbasedontheweb.pyframework.This
sectionisentirelyreferencedfromweb.pytutorials(http://webpy.github.io/).Inorderto
installweb.py,aPythonmoduleinstallersuchaspiporeasy_installisrequired.Wewill
installitusingthefollowingcommand:
sudoapt-getinstallpython-setuptools
Engagethrusters
Theweb.pyframeworkcanbeinstalledusingtheeasy_installtool:
sudoeasy_installweb.py
Oncetheinstallationiscomplete,itistimetotestitwithaHelloWorld!example.
WewillopenanewfileusingatexteditoravailablewithPythonIDLEandgetstarted
withaHelloWorld!examplefortheweb.pyframeworkusingthefollowingsteps:
1. Thefirststepistoimporttheweb.pyframework:
importweb
2. Thenextstepisdefiningtheclassthatwillhandlethelandingpage.Inthiscase,itis
index:
urls=('/','index')
3. WeneedtodefinewhatneedstobedonewhenonetriestoaccesstheURL.Wewill
liketoreturntheHelloworld!text:
classindex:
defGET(self):
return"Helloworld!"
4. Thenextstepistoensurethatawebpageissetupusingtheweb.pyframeworkwhen
thePythonscriptislaunched:
if__name__=='__main__':
app=web.application(urls,globals())
app.run()
5. Wheneverythingisputtogether,thefollowingcodeiswhatwe’llsee:
importweb
urls=('/','index')
classindex:
defGET(self):
return"Helloworld!"
if__name__=='__main__':
app=web.application(urls,globals())
app.run()
6. WeshouldbeabletostartthewebpagebyexecutingthePythonscript:
pythonhelloworld.py
WeshouldbeabletolaunchthewebsitefromtheIPaddressoftheRaspberryPi.For
example,iftheIPaddressis10.0.0.10,thewebpagecanbeaccessedat
http://10.0.0.10:8080anditdisplaysthetextHelloworld.Yay!
AHelloworld!exampleusingtheweb.pyframework
Objectivecomplete–missiondebriefing
WebuiltasimplewebpagetodisplaytheHelloworldtext.Inthenexttask,wewillbe
interfacingtheChristmastreeandotherdecorativeappliancestoourwebpagesothatwe
cancontrolitfromanywhereonthelocalnetwork.
Itispossibletochangethedefaultportnumberforthewebpageaccessbylaunchingthe
Pythonscriptasfollows:
pythonhelloworld.py1234
Now,thewebpagecanbeaccessedathttp://<IP_Address_of_the_Pi>:1234.
Interfacingthewebserver
Inthissection,wewilllearntointerfaceonedecorativeapplianceandaspeaker.Wewill
createaformandbuttonsonanHTMLpagetocontrolthedevices.
Prepareforliftoff
Inthistask,wewillreviewthecode(availablealongwiththischapter)requiredto
interfacedecorativeappliancesandlightingarrangingtoawebpageandcontrolledovera
localnetwork.Let’sgetstartedwithopeningthefileusingatexteditingtool(Python
IDLE’stexteditororanyothertexteditor).
Engagethrusters
1. Wewillimportthefollowingmodulestogetstartedwiththeprogram:
importweb
fromwebimportform
importRPi.GPIOasGPIO
importos
2. TheGPIOmoduleisinitialized,theboardnumberingisset,andensurethatall
appliancesareturnedoffbysettingtheGPIOpinstoloworfalseanddeclareany
globalvariables:
#Setboard
GPIO.setmode(GPIO.BCM)
#Initializethepinsthathavetobecontrolled
GPIO.setup(25,GPIO.OUT)
GPIO.output(25,False)
3. Thisisfollowedbydefiningthetemplatelocation:
urls=('/','index')
render=web.template.render('templates')
4. Thebuttonsusedinthewebpagearealsodefined:
appliances_form=form.Form(
form.Button("appbtn",value="tree",class_="btntree"),
form.Button("appbtn",value="Santa",class_="btnSanta"),
form.Button("appbtn",value="audio",class_="btnaudio")
)
Inthisexample,threebuttonsareused,avalueisassignedtoeachbuttonalong
withtheirclass.
Inthisexample,weareusingthreebuttonsandthenameisappbtn.Avalueis
assignedtoeachbuttonthatdeterminesthedesiredactionwhenabuttonis
clicked.Forexample,whenaChristmastreebuttonisclicked,thelightsneedto
beturnedon.Thisactioncanbeexecutedbasedonthevaluethatisreturned
duringthebuttonpress.
5. Thehomepageisdefinedintheindexclass.TheGETmethodisusedtorenderthe
webpageandPOSTforbuttonclickactions.
classindex:
defGET(self):
form=appliances_form()
returnrender.index(form,"RaspberryPiChristmaslights
controller")
defPOST(self):
userData=web.input()
ifuserData.appbtn=="tree":
globalstate
state=notstate
elifuserData.appbtn=="Santa":
#dosomethinghereforanotherappliance
elifuserData.appbtn=="audio":
os.system("mpg321/home/pi/test.mp3")
GPIO.output(25,state)
raiseweb.seeother('/')
InthePOSTmethod,weneedtomonitorthebuttonclicksandperformanaction
accordingly.Forexample,whenthebuttonwiththetreevalueisreturned,we
canchangetheBooleanvalue,state.Thisinturnswitchesthestateofthe
GPIOpin25.Earlier,weconnectedthepowertailswitchtopin25.
6. Theindexpagefilethatcontainstheformandbuttonsisasfollows:
$defwith(form,title)
<html>
<head>
<title>$title</title>
<linkrel="stylesheet"type="text/css"href="/static/styles.css">
</head>
<body>
<P><center><H1>ChristmasLightsController</H1></center>
<br/>
<br/>
<formclass="form"method="post">
$:form.render()
</form>
</body>
</html>
7. Thestylesofthebuttonsusedonthewebpagearedescribedasfollowsin
‘styles.css‘:
form.btntree{
margin-left:200px;
margin-right:auto;
background:transparenturl("images/topic_button.png")no-repeattop
left;
width:186px;
height:240px;
padding:0px;
position:absolute;
}
form.btnSanta{
margin-left:600px;
margin-right:auto;
background:transparenturl("images/Santa-png.png")no-repeattop
left;
width:240px;
height:240px;
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8. Thewebpagelookslikewhatisshowninthefollowingfigure:
Yay!WehaveaChristmaslightscontrollerinterface.
Objectivecomplete–minidebriefing
WehavewrittenasimplewebpagethatinterfacesaChristmastreeandRGBtreeand
playsMP3files.Thisisagreatprojectforaholidayweekend.
ItispossibletoviewthiswebpagefromanywhereontheInternetandturnthese
applianceson/off(FansoftheTVshowBigBangTheorymightlikethisidea.Astep-by-
stepinstructiononsettingitupisavailableat
http://www.everydaylinuxuser.com/2013/06/connecting-to-raspberry-pi-from-
outside.html).
Missionaccomplished
Inthisproject,wehaveaccomplishedthefollowing:
InterfacingtheRGBmatrix
InterfacingACappliancestoRaspberryPi
Designofawebpage
Interfacingdevicestothewebpage
Weusedexamplestodemonstratethecapabilitiesofenhancingthefestivedecoration
usingtheRaspberryPi.Itisdefinitelypossibletoenhancethisprojectusingourcreativity.
References
Youcanfindweb.pytutorialsathttp://webpy.github.io/docs/0.3/tutorial.
ThePythonPit–DriveyourRaspberryPiwithamobilephone,MagPiFebruary2013
edition,page34,(http://www.themagpi.com/issue/issue-9/article/the-python-pit-drive-
your-raspberry-pi-with-a-mobile-phone/)
Chapter5.InternetofThingsExample–
AnE-mailAlertWaterFountain
Inthisproject,wewillworkonbuildingawaterfountainenabledbyRaspberryPi.We
willalsodecoratethefountainwithlightingthatcanbecontrolledwiththehelpofaweb
interface.Thisfountainwillenableustoreceiveemailalertsaswell.Itisagreatexample
toenabletheInternetofThingsusingtheRaspberryPi.
Missionbriefing
WewilllearntobuildafountainandcontrolitusingaRaspberryPi.Wewillbuildaweb
pagebasedontheFlaskframeworkandtrytocontrolthelightingarrangementonthe
fountain.Wewilldemonstratehowadecorativepiece,suchasatabletopfountain,canbe
usedtoreceivee-mailortweetalerts.
FollowingisanimagethatshowsafountaincontrolledbytheRaspberryPi:
Whyisitawesome?
Tabletopfountainsaresoothingineffectandplayagreatroleinrelievingstress.Itisfun
tohaveaRaspberryPiplayagreatroleincontrollingourbehavior.Italsoenablesusto
remindourselvestocheckoure-mails/Twitterfeedsonaregularbasis.
Yourobjectives
Inthisproject,wewillbuildthetabletopfountaininthefollowingsteps:
Assemblingthefountain
InstallationoftheFlaskframeworkandinterfacingthefountain
ControllingRGBLEDsfromthewebpage
Settingupe-mailalertsforthefountain
Missionchecklist
Atabletopfountaincanbebuiltinseveralways,anditispossibletoincludealotof
decorativepiecestoenhancetheappeal.Theitemslistedinthefollowingtableincludea
basiclistofitemstodemonstrateafountaincontrolledbyaPi:
Item Cost
(approximate)
ADIYfountainkit,includingcontainer,pebbles,andsoon(fromhomeimprovementcompaniessuch
asHomeDepotoraDIYproductsuppliersuchasAmericanScienceandSurplus). 30USD
Asubmersiblepump(source:sameastheprecedingkit). 10USD
AdigitallyaddressableRGBLEDstrip(AdafruitorBanggood.LinktosourcesofLEDprovidedin
thepreviousproject).
16.00/meter
USD
Awoodendowelrod(source:anyhobbystore). 2.00USD
Anacrylicsheet(source:anyhomeimprovementstore). 12.00USD
Mountingaccessories(scotchtapeandsoon). 10.00USD
Inthistask,wewillgetstartedwithassemblingthewaterfountainforourproject.The
fountainassemblyisasimplethree-stepprocess.Thereareseveralresourcesavailable
onlinetobuildadesktopfountainusingrawmaterialsavailableathome(asomewhat
simpletutorialonbuildingatabletopfountainusingasubmersiblefromapetstore:
http://www.instructables.com/id/Table-Fountain/).Wewilllookintoanexampleusingan
off-the-shelfDIYfountainkitinthisstep.
Prepareforliftoff
IfthereaderisnotabletogainaccesstoaDIYfountainkit,thefollowingitemsare
required:
Abasin(preferablyopaquesothatitdiffuseslight)
Afountain/submersiblepumpfromapetshop
Pebblesandgravel
Decorativeaccessoriesavailablefromaquariums
Theseitemscouldbepurchasedfromahobbyshoporanaquariumsuppliesstore.
Engagethrusters
1. TheDIYtabletopfountainkitcomeswithabasinthathasaprovisiontorunthe
fountainpump’scableoutofthebasinthroughasealedoutlet.
Abasinwithasealedelectricaloutlet
2. Next,wewillplacethefountainpumpinsidethebasin.
Fountainpumptobeplacedinsidethebasin
3. Wewillnowcoverthepumpwithacoverandplaceadecorativepot.
Fountainpumpcoveredwithadecorativepot
4. Wecanfillthesidesofthepumpwithgravel,pebbles,smallpiecesofrock,andother
decorativeaccessories.Wethenturnonthepumpandtestthewaterflowtomake
surethatwedon’tspillwaterandmakeamess.
Afountainwithdecorativeaccessories
5. We’llwrapthefountainwithadigitallyaddressableRGBLEDstripandwearedone
withassemblingthefountainwhenwepowerthefountainalongwiththeRGBLEDs.
AwaterfountainstrappedwithadigitallyaddressableRGBLED
Objectivecomplete–minidebriefing
Inthefirststep,wefinishedassemblingthefountainandtheRGBLEDstrip.Wewill
moveontoinstallawebframeworktoimplementlightingcontrolfortheframework,
whichwecanchangebasedonourneeds.
InstallationoftheFlaskframework
Inthistask,wewillinstalltheFlaskframeworkontheRaspberryPiandcompleteatest
webpageontheRaspberryPi.WewillusetheFlaskframeworktocontroltheRGBLED
strip.
Prepareforliftoff
Inthepreviousprojects,weinstalledpythonmoduleinstallerssuchaspipor
easy_install.Ifeitherofthesetoolsisn’tinstalled,theycanbeinstalledbyexecutingthe
followingcommand:
sudoapt-getinstallpython-pip
Alternatively,youcanusethefollowingcommand:
sudoapt-getinstallpython-setuptools.
Next,wewillworkoninstallingtheFlaskframeworkandthefirstexample.
Engagethrusters
1. TheFlaskframeworkisinstalledusingthefollowingcommand:
sudoeasy_installflask
2. Oncetheinstallationiscomplete,wewilluseanexampleavailablefromtheFlask
frameworkdocumentation(http://flask.pocoo.org/docs/0.10/quickstart/#quickstart)
andcreateaPythonscript(usingPythonIDLE’seditor):
fromflaskimportFlask
app=Flask(__name__)
@app.route("/")
defhello():
return"HelloWorld!"
if__name__=="__main__":
app.run()
3. WhenweexecutethesavedfileandexecutethePythonscript,thewebserveris
launchedlocallyontheRaspberryPi:
pythonhelloworld.py
*Runningon
http://127.0.0.1:5000/
4. ThewebserverisonlyvisibletotheRaspberryPiandawebpage(webaddress:
http://127.0.0.1:5000)islaunchedontheRaspberryPi’sbrowser,whichwill
showthetextHelloWorld!.
AnHelloWorldexampleontheFlaskframework-basedwebserver
5. Inordertomakethewebservervisibletoalldevicesonthelocalnetwork,weneed
tochangethefollowinglineinthePythonscript:
app.run('0.0.0.0')
Objectivecomplete–minidebriefing
Inthistask,wearedoneinstallingtheFlaskframeworkforcontrollingtheframework.We
willmoveontothenexttasktosetupthings.
ControllingRGBLEDsfromawebpage
Inthistask,wewilllearnhowtocontroltheRGBLEDsfromawebpage.Wewillusethe
digitallycontrolledRGBLEDstripfromAdafruitIndustries.Wewillinterfaceacolor
pickerandsetthecoloroftheRGBstrip.Thecolorpickerwheelwasborrowedfrom
circadianlightingproject,ChrisFane,distributedunderMITlicense.
(https://github.com/rasathus/circadianLighting).Wewillmodifythiscodesampletosuit
ourneeds.We’llalsousetheLPD8806librarywrittenbyAdamHaile,distributedunder
GPLv3license.(https://github.com/adammhaile/RPi-LPD8806.git).
Prepareforliftoff
SinceweareusingthedigitallyaddressableRGBLEDstrip,weneedtoenabletheSPI
driversontheRaspberryPi.
Note
EnablingofSPIdriversisnotnecessaryiftheyouhaveinstalledOccidentalisinProject2,
ARaspberryWebIDEExample.
Thefollowingfileneedstobemodified:/etc/modprobe.d/raspi-blacklist.conf.
Theblacklistspi-bcm2708lineneedstobecommentedout(adda#atthestartofthe
line).Thenwegetthedriversworkingbyexecutingthefollowingcommand:
sudomodprobespi_bcm2708
TheSPIdevicescanbefoundlistedinthe/devdirectory:
SPIdeviceslistedinthedirectory
Engagethrusters
1. TheRaspberryPineedstobeconnectedtotheSPIinterfaceoftheRaspberryPi.The
RGBLEDstriphastobepoweredbya5VDCadapter.TheclockpinCIneedstobe
connectedtotheclockpinoftheRaspberryPi(pin14,SCKpinoftheRaspberryPi).
TheclockpinCIneedstobeconnectedtotheclockpinoftheRaspberryPi(pin
14oftheGPIOheader,SCKpinoftheRaspberryPi).
ThedatapinDI(DataIn)needstobeconnectedtotheMOSIpin(pin12ofthe
GPIOheader)oftheRaspberryPi.
TheGND(groundpin)oftheRGBLEDstripneedstobeconnectedtothe
GND(groundpin)oftheGPIOheaderoftheRaspberryPi.
ConnectingtheRGBLEDStriptotheRaspberryPiusingaPiCobbler
2. Inordertocontrolthelightingarrangement,let’smakeuseoftheCircadianlighting
project’sPythonscriptandAdamHaile’sLPD8806library.Wewillgetstartedby
importingtheFlaskframeworkandtheLPD8806library.Wewillinitializethe
LPD8806librarybysettingthenumberofdigitallyaddressableRGBLEDsusedin
thisproject:
num=64
led=LEDStrip(num)
Thecircadianlightingproject(http://rasathus.blogspot.com/2013/02/nasa-style-
circadian-lighting-wrap-up.html)usesacolorpicker(basedonRaphael.js)and
acolorissetonmouseclick.Theclicksonthecolorpickerwheelareconverted
intoRGBvaluesasfollows:
rgb_array=[0,0,0]
HEX='0123456789abcdef'
HEX2=dict((a+b,HEX.index(a)*16+HEX.index(b))forainHEXfor
binHEX)
defrgb(triplet):
triplet=triplet.lower()
rgb_array[0]=HEX2[triplet[0:2]]
rgb_array[1]=HEX2[triplet[2:4]]
rgb_array[2]=HEX2[triplet[4:6]]
return
(HEX2[triplet[0:2]],HEX2[triplet[2:4]],HEX2[triplet[4:6]])
deftriplet(rgb):
returnformat((rgb[0]<<16)|(rgb[1]<<8)|rgb[2],'06x')
Wheneveraclickisdetected,thepostedhexvaluesfromthewebserverare
detectedasfollows:
@app.route('/set/<hex_val>',methods=['GET','POST'])
defsend_command(hex_val):
rgb_val=rgb(hex_val)
3. TheRGBvaluesarepassedtoLPD8806viatheRaspberryPi’sSPIinterface:
led.fill(Color(rgb_val[0],rgb_val[1],rgb_val[2],0.98))
led.update()
4. Now,whenweexecutethescriptavailablealonginthewebserversamplefolder,we
shouldbeabletolaunchawebserverthatwilldisplayacolourpickerasshowninthe
followingdiagram:
Aflaskframework-basedRGBinterface
Objectivecomplete–minidebriefing
Inthistask,wefinishedsettingupthewebserverthatcontrolsthefountain.Inthenext
task,wewillreviewsettingupe-mailalertsthroughcolourchangesonthefountain.
Itispossibletocontrolthelightsofthefountainbasedonasongbeingplayedonthe
RaspberryPi.Howcanthisbeachieved?Visitthisbook’swebsiteforsomeclues.
Setupofthee-mailalertsinthefountain
Inthistask,wewillreviewsettingupe-mailalertsfromGmailaccounts.Wecanblinkan
LED(asshowninthisstep)orflashtheRGBLEDstrip(thishastobeexecutedbythe
reader)whenane-mailofaspecificcategoryisreceived(forexample,worke-mail).
Prepareforliftoff
Wewillgetstartedbyinstallingthepython-feedparsertool.Googleprovidesaread-only
inboxfeedandwewillmakeuseofthefeedparsermoduletodeterminewhetherwe
receivedanynewe-mails.
sudoapt-getinstallpython-feedparser
Engagethrusters
1. Inordertologinandparsethroughthee-mailfeed,wegetstartedbyimportingthe
feedparsermodule:
importsys
importfeedparser
2. Wewilldefinethevariables,includingtheGmailusernameandpassword(changed
togenericnamesbelow)alongwiththefunctionthatretrievesallunreade-mails.
Refertothefollowingexample:
Note
Inthisexample,wearejustretrievingthecountofanynewunreade-mails.Itis
possibletoparseandidentifye-mailswithspecificlabels.Wewillleavethattothe
reader.Formoreinformation,referto
https://developers.google.com/gmail/gmail_inbox_feed.
newEmail=""
username="username@gmail.com"
password="password"
proto="https://"
server="mail.google.com"
path="/gmail/feed/atom"
defmail():
email=
int(feedparser.parse(proto+username+":"+password+"@"+server+path)
["feed"]["fullcount"])
returnemail
TheprecedingfunctionhasbeenborrowedfromtheWonderHowTowebsite
(http://null-byte.wonderhowto.com/how-to/make-gmail-notifier-python-
0132845/).
Let’ssavethisfunctioninaseparatefileandtrytocallitfromanotherfile.For
example,thefunctionhasbeensavedinafilecalledparser.py.
3. Now,wewillimporttheparsermodulebyopeninganotherfileasamoduleand
implementthee-mailnotifier.Inthisfile,wewillblinkanLEDwhenthereisanew
e-mail.WewillstartbyimportingtheparsermoduleandRPi.GPIO:
importparser
importtime
importRPi.GPIOasgpio
Wewillgetstartedbysettingtheoutputpinsforthee-mailnotifierexample:
gpio.setwarnings(False)
gpio.setmode(gpio.BCM)
gpio.setup(17,gpio.OUT)
Now,we’llcheckfornewe-mailsandblinkanLEDifthereisanunreade-mail:
whileTrue:
mail=parser.mail()#checkforemail
count=0
ifmail>0:#printfornewemails
print(mail)
print("newemails\n")
whilecount<10:
count+=1
gpio.output(17,gpio.HIGH)#blinkLEDiftherearenewemails
time.sleep(1)
gpio.output(17,gpio.LOW)
time.sleep(1)
gpio.output(17,gpio.LOW)#setLEDtolow
else:
time.sleep(10)#repeatcyclefor10seconds
TheLEDneedstobeconnectedasshowninthefollowingfigure:
ARaspberryPie-mailnotifier–SchematiccreatedwithFritzing,RaspberryPi
Library.Courtesy:Adafruit
Note
Inthistask,wejustmadeanLEDblinkwhenanewe-mailisreceived.Youshouldtryto
importtheLPD8806moduleandflashtheRGBLEDstrip.
Objectivecomplete–minidebriefing
Inthistask,wecompletedthesetupofthee-mailalertsaswellasauserinteraction
elementofblinkinganLED.Thisbringsustotheendoftheassemblyandsetupofthe
fountain.
Missionaccomplished
Inthisproject,weassembledafountain,awebserverframework,controlledtheRGB
LEDs,andsetupe-mailalerts.Theyshouldlookprettyaccordingtotheuser’screativity.
Hotshotchallenge
Inthisproject,wesetupe-mailalertswiththedisplay.IsitpossibletosetTwitteralerts?
Chapter6.RaspberryPiasaPersonal
Assistant
Inthisproject,wewillbuildatoolusingRaspberryPithatactsasapersonalassistant.
Thisprojectpresentsideastoovercomedifficultiesencounteredinourday-to-daylives
(forexample,keepingtrackofdailyappointments,payingbillsontime),overcome
procrastination,oreaseourroutinestressinducingactivitiesbyautomatingthem.
Missionbriefing
Inthisproject,webuildsomethingthathelpsinsimplifyingourday-to-dayactivities,ease
ourburdeninperformingmundanetasks,andremindusaboutimportant
appointments/tasksaswellastrackingthem.Wewillworkonimplementingasolutionfor
eachpossiblescenario(forexample,wewillimplementasolutiontochecke-mailsand
reviewasolutiontocreateanalertforanewe-mail).
Whyisitawesome?
Wedoourbesttobesuccessfulinourcareerandleadahealthylifestyle.Whilewriting
thisbook,wehadtocomeupwithaplantoovercomeourprocrastinationandtrackour
taskseffectively(especially,deliveringthedraftsofeachprojectontime!).
Yourobjectives
Inthisproject,wewillaccomplishthefollowing:
Settingupthee-mailfeedparser
Settinguptheparserforremindersandevents
Designinganenclosureforthepersonalassistant
Settinguptheassemblyforthedishmonitor
Settingupsensorsforthekeyalertsystem
Missionchecklist
Inthistask,wewillworkoninstallingalltoolsandPythonmodulesusedinthisproject:
1. Beforewestartinstallingthetoolsrequiredforthisproject,ifnecessary,youcan
updatetherepositoriesandpackagelistsasfollows:
sudoapt-getupdate
2. Wewillstartwithinstallingpython-feedparser.Weusedthepython-feedparser
toolinthepreviousprojectandcreatede-mailalertsforthewaterfountain.Ifyou
skippedthepreviousproject,thetoolcanbeinstalledasfollows:
sudoapt-getinstallpython-feedparser
3. WewilluseGoogleCalendartoorganizeeventsandappointmentsasanexample.We
needtoinstallthepython-gdatatooltomakeuseoftheGoogleAPIs:
sudoapt-getinstallpython-gdata
4. AnotherimportanttoolrequiredforthisprojectisOpenCV(http://opencv.org/).
OpenCVisanopensourcecomputervisionframeworkdevelopedbyIntel.OpenCV
iswidelyusedbyresearchersandhobbyistsinapplicationssuchasobject
recognition,machinevisionapplicationssuchascomponentinspectionona
manufacturingline,andmore.
Note
Itisimportanttoknowthatittakesatleastfourhourstofinishthecompilationof
OpenCV.
TheinstallationprocedureforOpenCVontheRaspberryPihasbeenborrowed
fromhttp://mitchtech.net/raspberry-pi-opencv/andtheOpenCVinstallation
guideforLinux
(http://docs.opencv.org/doc/tutorials/introduction/linux_install/linux_install.html).
Beforewegetstartedwiththeinstallationprocess,thedependenciesfor
OpenCVneedtobeinstalled.Thedependenciescanbeinstalledusingthe
followingshellscriptavailablealongwiththisproject:
shOpenCVInstall.sh
Oncethedependencieshavebeeninstalled,wecangetstartedwiththeOpenCV
installation.ThesourcefilestoinstallOpenCVcanbedownloadedfrom
http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.10/opencv-
2.4.10.zip.
Weneedtoextractthedownloadedsource:
unzipopencv-2.4.10.zip
ThenextstepisthemakefilegenerationusingCMake.Thelibraryhastobe
compiledwithPythonsupportthatenablesapplicationdevelopmentusinga
Pythonscriptlibraryandsupport.
cdopencv-2.4.5
mkdirbuild
cdbuild
cmake-DCMAKE_BUILD_TYPE=RELEASE-D
CMAKE_INSTALL_PREFIX=/usr/local-DBUILD_NEW_PYTHON_SUPPORT=ON-D
BUILD_EXAMPLES=ON
Oncethemakefilehasbeengeneratedsuccessfully,OpenCVcanbebuiltand
installedasfollows:
make
sudomakeinstall
Oncethelibraryhasbeeninstalled,weneedtotestwhethertheinstallationwas
successfulbyexecutingoneofthePythonsamplesavailableinOpenCV:
cd~/opencv-2.4.5/samples/python
pythondelaunay.py
Iftheinstallationwassuccessful,weshouldabletolaunchtheDelaunay
triangulationsample.
Delaunaytriangulation–OpenCV
5. NowthatwehaveinstalledOpenCV,wewillproceedtobuildourprojectoverthe
forthcomingtasksoftheproject.
Settingupthee-mailfeedparser
Inthistask,wewilllearntosetupane-mailfeedparserandblinkanLED.Asan
example,wewillchecknewe-mailsinaGmailaccount.
Prepareforliftoff
Sincewealreadyinstalledthepython-feedparsermodule,wewillgetstartedwith
settingupthemailparser.Wewillbuildeachmoduleofourprojectasaseparateexample.
Engagethrusters
1. UsingPythonIDLE,let’sgetstartedwithwritingapythonscripttoachievethistask.
Wewillgetstartedbyimportingthefeedparsermodule:
importsys
importfeedparser
2. Wewilldefinethefunctionrequiredtochecke-mails:
newEmail=""
username="username@gmail.com"
password="password"
proto="https://"
server="mail.google.com"
path="/gmail/feed/atom"
defmail():
email=
int(feedparser.parse(proto+username+":"+password+"@"+server+path)
["feed"]["fullcount"])
returnemail
Note
TheprecedingfunctionhasbeenborrowedfromtheWonderHowTowebsite
(http://null-byte.wonderhowto.com/how-to/make-gmail-notifier-python-0132845/).
Let’ssavethisfunctioninaseparatefileandtrytocallitfromanotherfile.For
example,thefunctionhasbeensavedinafilecalledparser.py.
Wewillimportparser.pyinanotherfileasamoduleandimplementthee-mail
notifier.Inthisfile,wewillblinktheLEDwhenthereisanewe-mail.Wewill
startbyimportingtheparsermoduleandRPi.GPIO:
importparser
importtime
importRPi.GPIOasgpio
Wewillgetstartedbysettingtheoutputpinsforthee-mailnotifierexample:
gpio.setwarnings(False)
gpio.setmode(gpio.BCM)
gpio.setup(17,gpio.OUT)
Wewillcheckfornewe-mailsandblinkanLEDifnecessary:
whileTrue:
mail=parser.mail()#checkforemail
count=0
ifmail>0:#printfornewemails
print(mail)
print("newemails\n")
whilecount<10:
count+=1
gpio.output(17,gpio.HIGH)#blinkLEDiftherearenewemails
time.sleep(1)
gpio.output(17,gpio.LOW)
time.sleep(1)
gpio.output(17,gpio.LOW)#setLEDtolow
else:
time.sleep(10)#repeatcyclefor10seconds
3. TheLEDneedstobeconnectedasshowninthefollowingdiagram:
RaspberryPiemailnotifier–SchematiccreatedwithFritzing,RaspberryPiLibrary
Settinguptheparserforremindersand
events
Inthistask,wewillimplementamodulethatwillblinkanLEDtoremindusabout
importanteventsandappointments.
Prepareforliftoff
TheGoogleDataPythonclientlibraryisrequiredforthistask.Youalsohavetosavesome
tasksinyourcalendartotesttheimplementation.
Engagethrusters
1. UsingthePythonIDLE’seditor,let’sgetstartedbycreatinganewfilecalled
calendars.py:
importgdata.calendar.service
importgdata.service
importgdata.calendar
importtime
2. WecangetstartedbydefiningaGoogleCalendarobject.Wewilldefinethe
usernameandpasswordforourGoogleaccount:
calendar_service=gdata.calendar.service.CalendarService()
calendar_service.email='username@gmail.com'
calendar_service.password='password'
calendar_service.ProgrammaticLogin()
3. Thecalendar_queryfunctionperformsaqueryforcalendareventsbydefininga
timeframeasfollows:
query=
gdata.calendar.service.CalendarEventQuery('default','private','full')
query.start_min='2014-01-01'
query.start_max='2013-05-31'
feed=calendar_service.CalendarQuery(query)
returnfeed
4. Let’screateanotherPythonscriptandtestthefunctionalityofthecalendarmodule
(calendar.py).Wewillbeginbyimportingthepreviousdefinitionasamodule:
importcalendar
feed=calendar.calendar_query()
Now,wewillprintthedetailsoftheretrievedevents:
fori,an_eventinenumerate(feed.entry):
print'\t%s.%s'%(i,an_event.title.text,)
fora_wheninan_event.when:
print'\t\tStarttime:%s'%(a_when.start_time,)
print'\t\tEndtime:%s'%(a_when.end_time,)
TheprecedingexamplewasborrowedfromthedocumentationoftheGoogle
CalendarAPI.Whenexecuted,theoutputwouldbesomethinglikethe
following:
0.Sai
Starttime:2013-05-12T11:30:00.000-05:00
Endtime:2013-05-12T12:30:00.000-05:00
1.EventatFiregrillhouse
Starttime:2013-04-24T18:30:00.000-05:00
Endtime:2013-04-24T19:30:00.000-05:00
2.ChicagoHardwareStartupMeetup-FIRSTMEETING
Starttime:2013-01-23T18:30:00.000-06:00
Endtime:2013-01-23T21:00:00.000-06:00
3.FreescaleSABRELiteBoard
Starttime:2013-01-30T12:00:00.000-06:00
Endtime:2013-01-30T13:00:00.000-06:00
5. SinceweareabletoretrieveandparsetheeventsontheGoogleCalendar,wewilltry
toblinkanLEDtoremindusabouttheeventsandappointments.
WewillgetstartedwithimportingtheRPi.GPIOmoduleinthesamefile:
importcalendar_special
importtime
importdatetime
importRPi.GPIOasgpio
Sinceweusedpin17forthee-mailalerts,let’susepin24forremindersand
events.
TheeventscanberetrievedfromGoogleCalendarasfollows:
feed=calendar_special.calendar_query()#retrieveeventsfrom
calendar
fori,an_eventinenumerate(feed.entry):
fora_wheninan_event.when:#Weretrievethestarttimeand
endtimeforeachappointment/event
try:
start_time=
datetime.datetime.strptime(a_when.start_time.split(".")[0],"%Y-%m-
%dT%H:%M:%S")
end_time=
datetime.datetime.strptime(a_when.end_time.split(".")[0],"%Y-%m-
%dT%H:%M:%S")
exceptValueError:
print(ValueError)
continue
current_time=datetime.datetime.now()
ifend_time>current_time:#Hastheeventended?
print'\t%s.%s'%(i,an_event.title.text,)
print'\t\tStarttime:%s'%(a_when.start_time,)
print'\t\tEndtime:%s'%(a_when.end_time,)
Wewillfilteroutallupcomingeventsandlistthemwithdetails.Wewillcheck
whetherwehavesetanalertfortheevent.Ifindeedtherewasanalert,wewill
blinkanLEDuntiltheeventhasended:
forreminderina_when.reminder:
ifreminder.method=="alert"\
andstart_time-datetime.timedelta(0,60*int(reminder.minutes))
<current_time:
print'\t%s.%s'%(i,an_event.title.text,)
print'\t\tStarttime:%s'%(a_when.start_time,)
print'\t\tEndtime:%s'%(a_when.end_time,)
count=0
gpio.output(24,gpio.HIGH)
time.sleep(1)
gpio.output(24,gpio.LOW)
time.sleep(1)
Designinganenclosuredesignforthe
personalassistant
Inthistask,wewilllookintotheenclosuredesignfortheproject.Inordertomakethings
simple,wewilluseadesignthatisopensource.Theenclosureisonethatcanbe
assembledinfewsimplesteps.ThisenclosurewasdesignedbyMichaelMilazzo
(http://makezine.com/2013/01/18/laser-cutting-a-glueless-acrylic-project-box/).
Prepareforliftoff
Thisenclosurecanbefabricatedinfewsimplestepsusingalasercutter.Thedesign
availablealongwiththisprojectinthePDFformatcanbemodifiedusingadesigntool
suchasInkscapeorAdobeIllustrator.
Engagethrusters
1. Theenclosuredesignismeanttobemanufacturedusingalasercutter.Sincelaser
cutterscanbeeasilyaccessedfromhackerspaces,openworkshops,andsoon,it
shouldbeeasytomakethisenclosure.
2. Alasercutteriseasytousewhenweadheretosafetypractices.Youmustundergo
trainingtooperatealasercutter.Thefilesusedforlasercuttingareavailablefromthe
precedinglink.
3. Oncethelasercuttingoperationiscomplete,thepartsoftheenclosurelooklikethe
oneshowninthefollowingimage:
AGluelessbox
4. Theassemblyoftheenclosureisquiteintuitive.Wewillmakeuseofthisenclosure
inthelaterpartofthisproject.
Anassembledenclosure
Settinguptheassemblyforthedish
monitor
Inthistask,wewillsetupamonitoroverthekitchensink.Wewillcheckwhetherthere
aredishesinthesinkandsendLEDalertstotheuser.SincewehaveinstalledOpenCV
already,wewillgetstartedwiththesetupofthemonitor.
ThistaskwasinspiredbyahackerbasedinLondonwhobuiltadishdetectortoalertusers
ofacommunalkitchen.
Note
ThecodesampleforthisfunctionhasbeenborrowedfromtheOpenCVDishDetector
projectbyTom:http://beagleboard.org/blog/2013-11-26-project-spotlight-dirty-dish-
detector/
Prepareforliftoff
Wewillgetstartedbymountingacameraontopofthesinkandconnectingittoan
overheadcamera,asshowninthefollowingimage:
Anoverheadcameraontopofthesink
Engagethrusters
1. WewillgetstartedbyimportingtheOpenCVmodule:
importtime
importsys
importcv2.cvascv
2. Wewillinitializethecameratocaptureframes:
capture=cv.CaptureFromCAM(0)
3. Afterinitialization,wewillgrabaframeforprocessing:
im=cv.QueryFrame(capture)
4. We’llconverttheimagetograyscaleforimageprocessingandfeaturedetection:
gray=cv.CreateImage(cv.GetSize(im),8,1)
edges=cv.CreateImage(cv.GetSize(im),cv.IPL_DEPTH_8U,1)
cv.CvtColor(im,gray,cv.CV_BGR2GRAY)
5. Wewillextractthefeaturesoftheimageusingthecannyedgedetectiontechnique.
Sincetheinformationispronetonoise,weusethesmoothingtechniquetoeliminate
thenoiseintheimage:
cv.Canny(gray,edges,200,100,3)
cv.Smooth(gray,gray,cv.CV_GAUSSIAN,3,3)
6. Wewillattempttodetectthedishesusingcommonshapesfoundinthedishes.The
techniqueiscalledHoughtransformsandwewilltrytodetectcircularobjectsin
theimage:
storage=cv.CreateMat(640,1,cv.CV_32FC3)
cv.HoughCircles(gray,storage,cv.CV_HOUGH_GRADIENT,1,30,100,55,0,0)
7. Wewilldrawacirclearoundeachobjectdetected.Thishelpsineliminatingany
incorrectobjectdetection:
foriinrange(storage.rows):
val=storage[i,0]
vessels=vessels+1#incrementdishesdetectedby1
radius=int(val[2])
center=(int(val[0]),int(val[1]))
cv.Circle(im,center,radius,(0,0,255),3,8,0)
8. Theobjectsdetectedcanbeviewedasfollows:
DishesdetectedinOpenCV
9. Ifavesselisdetected,wewilltriggeranLEDalerttoannoytheuser.
Objectivecomplete–minidebriefing
WehavesetupadishmonitortoalerttheuserwhendishesaredetectedusinganLED.
Settingupsensorsforthekeyalertsystem
Inthistask,wewilltrytobuildamodulethattriestoalerttheuserifthethingsthatwe
usedaily(suchasthekeystoourapartmentdoororthecarkey)arenotfoundintheright
place.Ithelpsussavealotoftimefranticallysearchingformisplaceditems.Wewillusea
reedswitchandamagnetforthismodule.
Theuniquenessaboutthistaskisthatwetrytoimproveourliveswithsimpleitemsthat
areeasytopurchaseandsimpletobuild.Amagnetandareedswitchareavailablefrom
allhobbystores.Youcanalsouseareedswitchindoorsecuritysystems.Thefollowingis
adiagramofareedswitchinterfacedtoaRaspberryPi:
ReedswitchsetupwiththeRaspberryPiGPIO
Prepareforliftoff
Wewillinterfacethereedswitchasshownintheprecedingdiagram.Let’stestitona
breadboardbeforesettingitupinanenclosure:
ReedswitchinterfacedtoRaspberryPi
Engagethrusters
1. Wewillbetrackingwhetherthekeyisintherightplacebyattachingabarmagnetto
thekeys.WewillsetupaGPIOpinaswegetstarted:
importRPi.GPIOasGPIO
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(18,GPIO.IN)
2. Wewillreadtheinputsandifthemagnetinthekeyisnotnearbythereedswitch,we
shouldbeabletotriggeranalert:
whileTrue:
if(GPIO.input(18)):
print("Keysareintherightplace")
else
print("Keysmissing!")
3. Nowthatwehavesetaninputforthereedswitch,weshouldbeabletosetupthe
reedswitchinsidetheenclosureasshowninthefollowingimage:
Areedswitchwiththemagnetattachedtothekey
Objectivecomplete–minidebriefing
Inthistask,youlearnedtouseasimplereedswitchtotheRaspberryPiandhelpimprove
ourlives.
Missionaccomplished
Inthisprojectweimplementeddifferentmodules,includinge-mailalerts,calendaralerts,
adishmonitor,andakeyalertsystem.Weleaveittotheusertointegrateallsubsystems
usingtheircreativity.You(likeus)havelearnedtouseRaspberryPitoimproveour
qualityoflife.
Hotshotchallenges
HowcanweuseRaspberryPitoenhancethelivesofseniorcitizens?
Thedishdetectorisnoiseprone.Howcanitbeimproved?
References
1. OpenCVinstallationontheRaspberryPiavailableathttp://mitchtech.net/raspberry-
pi-opencv/.
2. OpenCVguideforinstallationonUbuntuavailableat
http://docs.opencv.org/doc/tutorials/introduction/linux_install/linux_install.html.
3. PythonGmailnotifierfromtheWonderHowTowebsite,http://null-
byte.wonderhowto.com/how-to/make-gmail-notifier-python-0132845/.
4. GoogledataclientAPIdocumentationforGoogleCalendar.
5. GoogleCalendarusingpynotifybyJulienDanjou.
6. OpenCVdishdetector,availableat,
http://www.adafruit.com/blog/2014/03/11/beaglebone-black-used-to-detect-dirty-
dishes-beagleboneblack-txinstruments-beagleboardorg/,Tom,Londonhackerspace.
Chapter7.RaspberryPi-basedLine
FollowingRobot
Inthisproject,wewillbuildalinefollowingrobotthatiscontrolledbyyourRaspberryPi.
Note
ItisabsolutelynotnecessarytomakeuseoftheRaspberryPitobuildalinefollowing
robotunlessyouareusingacameratofollowtheline.Wearebuildingthisrobotto
demonstrateanexampleofbuildingamechatronicsystemusingtheRaspberryPi.
Missionbriefing
Inthisproject,wewillbuildalinefollowingrobotthatwillfollowablacklineagainsta
whitebackground.Therobotwillmakeuseofapairofinfraredsensorstotrackthe
orientationoftherobotanddrivetherobotaccordingly.
Alinefollowingrobot
Whyisitawesome?
ThePi,asyouhaveseeninthelastfewprojects,offersyouimmensefunctionalityand
manyadvantagesovermicrocontrollers.Youcanbringthispowerandsmallerfootprints
torobotics.So,wearegettingyoustartedoffwiththelinefollowingrobot.Onceyouget
thisundercontrol,thepossibilitiesareendless,makingthisanawesomesegueinto
roboticsandbeyond.
YourHotshotobjectives
Inthisproject,wewillbuildthelinefollowingrobotinthefollowingsteps:
AssemblyofthePiPlateforthelinefollowingrobot
Sensorselection,interfacingsensors,anddatainterpretation
Implementationoflinefollowinglogicbasedonsensordata
Testingthemotordrivercircuit
Preparationofthelinefollowingcourse
Designingthechassisforthelinefollowingrobot
Astep-by-stepassemblyoftherobot
Missionchecklist
Thereareoff-the-shelfproductsavailabletobuildalinefollowingrobot,forexample,
Make:itBasicRoboticsStarterKit(http://www.makershed.com/products/makeit-
robotics-start-kit).Alternatively,inordertobuildalinefollowingrobot,thefollowing
itemsarerequiredandthereadermayaddorremovecomponentstotherobotbasedon
his/hercreativity:
Item Cost
Alinefollowingsensorarray 10USD(intermsofcomponents)
DCmotorswithagearbox*2–60rpm(http://www.pololu.com/product/1594) 11USD
ArduinoUno(http://store.arduino.cc/product/A000066) 30USD
Plasticwheels–1pair(http://www.pololu.com/product/1425) 8USD
HBridgechip–forexample,L293D(http://www.pololu.com/product/24) 3USD
Anacrylicsheet(preferably12inchx24inchtocutthechassisusingalasercutter) 5USD
AUSBbatterypack(preferably10,000mAh,1Amaxoutput) 15USD
Aposterboard 3USD
PiPlatefromAdafruitIndustries(https://www.adafruit.com/product/801) 15USD
AssemblyofthePiPlatefortheline
followingrobot
Note
ThePiPlateisnecessaryonlyifyouaregoingtobuildyourowncircuitry(insteadofan
off-the-shelfrobotkit)thatdrivestherobot.
WewillmakeuseofthePiPlatefromAdafruitIndustries.ThePiPlateisstackableandan
add-onhardwarefortheRaspberryPi.ThePiPlateislikeabreadboard/perforated
prototypingboardandenablesprototypingusingtheRaspberryPiplatform.Wewill
assembletheheadersontheboard.
Prepareforliftoff
ThePiPlateisavailablefromAdafruitIndustries(www.adafruit.com).Itcosts15.95
USD.Thisstackableadd-onhardwareisusefulbecausethesensorsandactuatorscanbe
connectedusingthescrew-interminals.Thiswillavoidanylooseconnectionstoyour
RaspberryPiwhiletherobotisinmotion.
Engagethrusters
1. ThecontentsofthePiPlatepackageareasfollows:
ContentsofaPiPlatepackage
Note
AdultsupervisionisrequiredforsolderingandputtingthePiPlatetogether.
2. ThePiPlaterequiressolderingoftheterminals,andAdafruithassometutorialsin
settingupthePiPlate.Whentheterminalsandheadersareassembledtogether,we
havewhatisshowninthefollowingimage:
APiPlatestackedontheRaspberryPi
Objectivecomplete–minidebriefing
ItisunlikelythattherewillbeaproblemwiththePiPlateunlessthereisacoldsolder.
Sensorselection,interface,anddata
interpretation
Inthistask,wewilldiscussthedifferentsensorsavailabletobuildalinefollowingrobot
andpickasensorforthisproject.
Engagethrusters
Wewilldiscussthreesensorsinthistask,includinglightdetectingresistors,IR
emitters/detectors,andacamera.Wewilldiscusstheiroperations,features,andtheir
distinctedgeoverothersensingtechniquesaswellastheirdisadvantages.
LightDependentResistors
Asthenamesuggests,LightDependentResistorsarethosethatchangetheirresistance
whenlightisincidentonthesurfaceoftheresistor.
LightDependentResistorsareusedincombinationwithabrightLED.Wecanmakeuse
ofthedifferenceinreflectivitybetweendifferentcolouredsurfacestofollowablackline
onadarksurface.
WhenLightDependentResistorisinsertedintoapotentialdividerconfiguration,as
showninthefollowingdiagram,thedropinvoltagecausesapotentialimbalanceleading
toachangeinvoltage.Sincethereflectanceofwhiteandblackcolorsurfacesvaries,the
changeinvoltagecanbeusedtodistinguishbetweenblackandwhitecolors.This
propertyofLightDependentResistorscanbeusedinourlinefollowingrobot:
ALightDependantResistorinapotentialdividerconfiguration
Thepotentiometerinthepotentialdividerconfigurationisusedtoadjustthesensitivityof
LightDependentResistorsdependinguponthesurroundinglightingconditions.
LightDependentResistorscanbeusedasasensortobuildalinefollowingrobot,except
inthosecaseswherethesensorresponsetimeisnottrivial.Hence,LDRscannotbeused
incaseswheretherobotisdesignedtomoveathigherspeeds.
LightDependentResistorshavetobecompletelyisolatedfromlightsourcesotherthanthe
brightwhiteLED.ThisistomakesurethattheLEDrespondstoreflectedlightfromthe
brightLED.
Infraredemitter/detector
Aninfrared(IR)emitter/detectorcombinationisthebestalternativetotheLight
DependentResistors.Inbothcases(theLDRandIRsensors),theemitter(ultrabright
whiteLED/IRLED)andthedetector(LightDependentResistorsorphotodiode)are
arrangednexttoeachother.
ThefollowingdiagramshowsthecircuitforanIRemitter/detector:
AnIRemitter/detectorforthelinefollowingrobot
Theprecedingfigureshowsaphotodiodethatisconnectedtotheinvertingterminalofan
op-amp.Thepotentiometer(thatisconnectedtothenon-invertingterminaloftheop-amp)
canbeusedtovarythesensitivityofthesensor.
Whenlightfallsonthephotodiode,itpullsdownthe10Kresistor,andhence,theoutput
oftheop-ampishigh.Thesignaldiode,1N4148,actsasasignallevelconverterbetween
5Vand3.3V(RaspberryPi’sGPIOpinsare3.3Vtolerant).Whenthe5Vsideishigh,the
3.3Vsideisalsohigh(thediodeisreversebiasedandhencethepullupresistorkeepsthe
3.3Vsidehigh).Whentheinfraredsensorisontopoftheblacksurface,theoutputofthe
op-ampislow(sincetheinvertingterminalishigh)andthepullupresistoronthe3.3V
sideispulleddown.Thus,theGPIOpinispulleddown.Theinfraredsensorshowninthe
precedingdiagramcanonlybeusedincontrolledlightingconditionsastheyareproneto
strayinfraredradiationfromdaylight.
Inconditionswheretherobothastooperateunderbroaddaylightconditions,theinfrared
transmitterandreceiverhastobepulsewidthmodulatedsothatthesensorcandistinguish
betweennoiseandtheactualsignal(moreinformationcanbefoundat
http://www.ermicro.com/blog/?p=1908).
Machine-vision-basedlinefollowingrobot
Thefinalalternativetoasensortobuildalinefollowingrobotisacamera.TheRaspberry
Pifoundationhasreleaseditsowncameramoduleanditisalsosimpletointerface.
Alinefollowingrobotcanbeimplementedbygrabbingaframefromthecameramodule
andconvertingitintoagrayscaleimage.Thegrayscaleimagecanbeusedtodetermine
thecurrentpositionoftherobotwithrespecttothelinethathastobefollowed.Since
whiteandgreysurfaceshavevaryinglevelsofgreycolour,theorientationoftherobotcan
becorrectedusingadifferentialsteeringmechanism.
Acamerawouldbeoverkillforbuildingalinefollowingrobottojustfollowablackline
onawhitesurfaceinanindoorenvironment(also,abitoverwhelmingforabeginner).
However,wecanuseitoutofanacademicinterest.
Sensorselection
Wehavediscussedthedifferentsensingoptionsavailableforbuildingalinefollowing
robot.Wewillchoosetheinfraredsensor.Wechosetheinfraredsensorforthefollowing
reasons:
Itcanbeusedonlyincontrolledlightingconditions(sinceweareusingan
unmodulatedinfraredlightsource)butservesasagoodstartforabeginner
Itisreadilyavailableandeasytointerface
Ithasadistinctedgeoverlightdetectingresistorssinceithasabetterresponsetime
Objectivecomplete–missiondebriefing
Inthistask,wediscussedthedifferentsensoroptionsavailableforalinefollowingrobot.
Implementationoflinefollowinglogic
basedonsensordata
Inthistask,wewillimplementasimplelinefollowingtechniqueusingtheinfraredsensor.
Wewillmakeuseofapairofinfraredsensorstotrackablacklineonawhitesurface.The
robotwillmoveforwardifboththesensorsareonawhitesurface.Therobotturnsleftif
theleftsensorisontheblacklineandviceversa.
Prepareforliftoff
ThesensorneedstobesolderedandconnectedtotheRaspberryPi(somethingliketheone
shownintheprecedingschematic).Alternatively,youmayuseasensorofyourchoice.
Engagethrusters
1. Asalways,wewillgetstartedbyimportingtherequiredmodules,especially
Rpi.GPIO:
importRPi.GPIOasGPIO
fromtimeimportsleep
2. Wewillsetthepinconfigurationthatwewilluseinthisprogram:
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(18,GPIO.IN)
GPIO.setup(25,GPIO.IN)
3. Thecontrollogicexplainedearlierisimplementedasfollows:
state=1
prev_state=0
whileTrue:
#bothsensorsareonwhitesurface
if((GPIO.input(18)==GPIO.HIGH)and(GPIO.input(25)==GPIO.HIGH)):
state=0
#leftsensoraloneisontheblacksurface
elif((GPIO.input(18)==GPIO.LOW)and(GPIO.input(25)==GPIO.HIGH)):
state=1
#rightsensoraloneisontheblacksurface
elif((GPIO.input(18)==GPIO.HIGH)and(GPIO.input(25)==GPIO.LOW)):
state=2
#ifsensorstatehaschangedsincelasttime,updatemotorcontrol
ifstate!=prev_state:
ifstate==0:
#moverobotforward
elifstate==1:
#turnrobotleft
elifstate==2:
#turnrobotright
prev_state=state
sleep(0.15)
Thesensorstatesarecheckedonceevery15milliseconds.Ifthereisachangeof
sensorstates,themotorcontrolisupdated(asperthelogicexplainedinthistask).
4. Sinceweareusingonlytwosensors,therobotrunscrisscrossacrosstheline.Inorder
toachievesmoothtrackingoftheline,asensorarrayisusedfordrivingthemotors
usingacontrolalgorithmsuchasaPIDcontrolalgorithm.
Objectivecomplete–minidebriefing
Inthistask,weimplementedthelinefollowinglogicforourrobot.Inthenexttask,we
willdiscussmotorcontroltodrivetherobotThiswouldbeeventuallyintegratedintothe
linefollowinglogic.
Testingthemotordrivercircuit
Inthisproject,wewilluseapairofDCmotorstodrivetherobot.WewilluseadualH-
bridge(SN754410)drivertocontroltheDCmotors.WewilluseasoftwarePWMlibrary
writtenfortheRaspberryPi.WechoseDCmotorsforthefollowingreasons:
1. DCmotorsareeasytooperateandcontrolusinganH-bridgeinterfacedtothe
RaspberryPi.
2. ThereisasoftwarePWMlibrarythatmakesiteasiertocontroltheDCmotors.
Inthistask,wewillimplementtheDCmotorcontrolcircuitandalsowriteaprogramto
controltheDCmotors.
Prepareforliftoff
WewillusethesoftwarePWMfunctionavailablewithRPi.GPIO.ThesoftwarePWM
functionisavailableonversionsgreaterthan0.5.3.WeneedtodeterminetheRPi.GPIO
versioninstalledontheRaspberryPiusingacommand-lineterminal:
python
importRPi.GPIO
RPi.GPIO.VERSION
Ifthereturnedvalueisearlierthan0.53,thepackagecanbeupdatedasfollows:
sudoapt-getupdate
sudoapt-getupgrade
WewillbemakinguseofpulsewidthmodulationtodrivetheDCmotors.Itisimportant
thatyoufamiliarizeyourselfwithpulsewidthmodulationtechniquestocontrolaDC
motor.WealsoneedtosetuptheDCmotorsfortestingbyconnectingthewheelstothe
motor(somethingsimilartothefollowingfigure):
DCmotorswithsolderedwiresandwheelswithstrappedsiliconetires
Wealsoneedtoconstructthemotorcontrolcircuitryasshowninthefollowingschematic:
ASN754410motorcontrolcircuitry
AnH-bridgecircuitisusedforbidirectionalcontrolofaDCmotorusingamicrocontroller
orRaspberryPi(https://itp.nyu.edu/physcomp/labs/motors-and-transistors/dc-motor-
control-using-an-h-bridge/).TheH-Bridgetakesin2inputsforeachmotor.Thefollowing
tableshowsalogictablethatdictatesthecontrolofamotorusinganH-Bridge:
TheSN754410truthtable
Forexample,ifpin1Aissettohighwhile2Aissettolowandtheleadsofthemotorare
connectedto1Yand2Yrespectively,themotorrotatesinonedirection,whileitrotatesin
theoppositedirectionwhen1Aissettolowand2Aissettohigh.
Engagethrusters
1. WewillgetstartedwiththetestingoftheDCmotorswithasimplePythonprogram.
Wewillgetstartedbyimportingthemodules:
importRPi.GPIOasGPIO
importtime
2. Wewilldeclarethepinsthatwillbeusedasoutputpins.WewillconnecttheGPIO
pins,8,9,10,and,11tomotordriverpins,1A,2A,3A,and4A,respectively:
GPIO.setwarning(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(8,GPIO.OUT)#connectedto1A
GPIO.setup(9,GPIO.OUT)#connectedto2A
GPIO.setup(10,GPIO.OUT)#connectedto3A
GPIO.setup(11,GPIO.OUT)#connectedto4A
3. Wetestboththemotorsbyrotatingtheminbothdirectionsfor10secondsand
stoppingthem:
whileTrue:
#Rotatebothmotorsforwardfor10seconds
GPIO.output(8,GPIO.HIGH)
GPIO.output(9,GPIO.LOW)
GPIO.output(10,GPIO.HIGH)
GPIO.output(11,GPIO.LOW)
sleep(10)
#Stopmotorsandrotateinreversedirections
GPIO.output(8,GPIO.LOW)
GPIO.output(10,GPIO.LOW)
#Goreverse
GPIO.output(9,GPIO.HIGH)
GPIO.output(11,GPIO.HIGH)
sleep(10)
#Stopmotorsandrotatebothinoppositedirections
GPIO.output(9,GPIO.LOW)
GPIO.output(11,GPIO.LOW)
GPIO.output(8,GPIO.HIGH)
GPIO.output(9,GPIO.LOW)
GPIO.output(10,GPIO.LOW)
GPIO.output(11,GPIO.HIGH)
sleep(10)
#StopMotors
GPIO.output(8,GPIO.LOW)
GPIO.output(9,GPIO.LOW)
GPIO.output(10,GPIO.LOW)
GPIO.output(11,GPIO.LOW)
4. Intheprecedingexample,boththemotorswererunningat100percentdutycycle.
Wewilllookintocontrollingthemotorsusingpulsewidthmodulation.Wewillset
thepinsasoutputanddeclaretheoperatingchannelfrequenciesforthePWMpins
(1kHz):
GPIO.setup(8,GPIO.OUT)#connectedto1A
GPIO.setup(9,GPIO.OUT)#connectedto2A
GPIO.setup(10,GPIO.OUT)#connectedto3A
GPIO.setup(11,GPIO.OUT)#connectedto4A
GPIO.output(9,GPIO.HIGH)
GPIO.output(11,GPIO.HIGH)
motor1=GPIO.PWM(8,1000)
motor2=GPIO.PWM(10,1000)
5. Wewillstartthepulsewidthmodulationsignal(10percentdutycycle–runsat10
percentoftheratedvoltage)asfollows:
motor1.start(10)
motor2.start(10)
Wecanvarythespeedofthemotorasfollows:
whileTrue:
motor1.ChangeDutyCycle(25)
motor2.ChangeDutyCycle(25)
sleep(15)
motor1.ChangeDutyCycle(50)
motor2.ChangeDutyCycle(50)
sleep(15)
motor1.ChangeDutyCycle(75)
motor2.ChangeDutyCycle(75)
sleep(15)
motor1.ChangeDutyCycle(100)
motor2.ChangeDutyCycle(100)
sleep(15)
Objectivecomplete–minidebriefing
Inthistask,weimplementedamotordrivercircuitryandtestedit.
Preparationofthelinefollowingcourse
Inthistask,wewillpreparethelinefollowingtrackfortherobot.
Prepareforliftoff
Therearetwoapproachestobuildingalinefollowingtrack.Theyincludethefollowing:
1. PrintatrackavailablefromParallaxandsetitontopofaposterboard.
2. UseelectricaltapeandbuildatrackusingatutorialfromPololu.
Thefollowingitemsarerequiredtocompletethistask:
1. Aposterboard
2. Apermanentmarker
3. Apencil
4. Aruler
5. A4sheets
Engagethrusters
1. Wewilluseareadilyavailablelineforthefollowingtrack
(http://www.parallax.com/sites/default/files/downloads/28136-S2-
PrintableTracks.pdf)designedfortheScribblerlinefollowingrobotfromParallax.
ThelinefollowingtrackfromParallaxconsistsof10individualpiecesoftrackthat
canbearrangedandcustomizedaccordingtoourneeds.
2. Wewillgetstartedwithprintingtwosetsofthetrackavailablealongwiththis
project’sdownloadsandarrangethemaccordingtoourneedsanddeterminethe
complicityofthetrack.Anexampleofthetrackisshowninthefollowingimage,and
thiscanbeconsideredthefastestwayofbuildingalinefollowingtrack:
Alinefollowingtrack
Useelectricaltapeandbuildatrack
Pololuhaspublishedanexcellenttutorial
(https://www.pololu.com/docs/pdf/0J22/building_line_courses.pdf)onbuildingatrack
usingelectricaltape.Theonlydisadvantagebehindusingthismethodtobuildatrackis
thatthewrinklesontheelectricaltapecanaffectthesmoothoperationoftherobot.
Designingthechassisforthelinefollowing
robot
Inthistask,wewilldesignthechassisforthelinefollowingrobot.Thereareseveral
optionsavailableintermsofdesigntoolsforthedesignofthechassis.WechoseAutodesk
Inventor,buttherearealotoftoolssuchasAutodesk123Dandsoon.
Prepareforliftoff
Thechassisfortherobotisfabricatedusingthelasercuttingtechnique.Youarewelcome
tofabricateyourownchassis.Wehavechosentouselasercuttingbecauseitistheeasiest
tocomplete.Thetechniqueinvolvesdesigningthechassisfollowedbypreparingthe
designforfabricationandlasercutting.
Youmaydownloadthedesignfileavailablealongwiththisprojectanduseitforlaser
cutting.ThereisatrialversionofAutodeskInventoravailablefordownloadanditcan
beinstalledandusedfordesigningacustomchassis.
Asamaker/hacker,itisimportantthatyoulearnhowtousethesetoolsandhowtodesign
achassis.
Note
Theuseoftoolssuchasalasercutterrequiressomebasictrainingandsupervision.Itis
importantthatyouundergotherequisitesafetytrainingbeforeoperatingsuchequipment.
Engagethrusters
1. Wewillbeginbyconsideringthecomponentsthatgointotherobot.Thecomponents
includetheinfraredsensors,aballcaster,twoDCmotors,theRaspberryPi,thePi
Plate,andthebattery.
2. SincethePiPlatewillbestackedontopoftheRaspberryPi,wewillmountthe
batteryonaseparateplatemountedontopoftheRaspberryPi.Thecomponent
positionsaredesignedbasedonintuition.Thechassisisshowninthefollowing
image:
Lasercutchassisoflinefollowingrobot
3. Thetopplatethatholdsthebatterypackisshowninthefollowingimage:
Atopplateusedtomountthebatteryofthelinefollowingrobot
Objectivecomplete–minidebriefing
Wehavefinisheddesigningthepartsandfabricatingthemusingalasercutter.
Astep-by-stepassemblyoftherobot
Inthistask,wewillassembletherobotinsimplestepsthatareaccompaniedbya
photographicalrepresentation.
Prepareforliftoff
Weneedtohavethefollowingpartsreadytoassembletherobot:
1. Topandbottomchassisplatesforthelinefollowingrobot
2. Infraredsensors
3. Apairof#2screwsandnuts(washersoptional)
4. AballcasterassemblywithscrewsfromPololu
5. 2*M2.5screwsformountingtheRaspberryPi(washersoptional)
6. 4*#61-inchscrewswithspacers(washersoptional)
7. ARaspberryPi
8. Velcro
9. Battery
10. 2DCmotors
11. Double-sidedtape
12. APiPlate
13. Amotordriver
Engagethrusters
1. Wewillgetstartedbymountingthecastorwheel.
Mountingthecastorwheel
2. WewillmounttheRaspberryPiusingM2.5screws.
RaspberryPimountedusingM2.5screws
3. ThisisfollowedbytheDCmotorscoupledwithwheelsusingthedouble-sidedtape.
TheDCmotorswithaplasticgearboxfromPololudonotcomewithamounting
hole,andhence,wewillusedouble-sidedtapetomountthemotors.Similarly,the
infraredsensorswerealsomountedusingdouble-sidedtapeatthecenterwitha
spacingthatishalfthewidthofthetrack.
DCmotorsmountedusingdouble-sidedtape
4. WewillmountthePiPlateandthetopchassisplate.Wewillusevelcrotomountthe
USBbatterypacktocompletethelinefollowingrobotassembly.
Anassembledrobot
5. Oncetheassemblyiscompleted,wehavetoconnectthemotorsandthesensorsto
getstartedwiththetesting.
Objectivecomplete–minidebriefing
Wehavecompletedtheassemblyofthelinefollowingrobotinthistask.Oncethemotor
controlcodeisimplementedintothelinefollowinglogic,weareallsettotestingtherobot
onthetrack.Thismayrequiresometweakingthemotorspeedtomaketherobottrackthe
lineeffectively.
Missionaccomplished
Inthisproject,webuiltalinefollowingrobotstepbystep.Wegotstartedwiththesensors
followedbymotorcontrol,chassisdesign,arenadesign,andintegration.Now,wehavea
linefollowingrobot.
Alinefollowingrobotonthearena
Hotshotchallenge
Inthisproject,wedidnotmakeuseofanymotorcontrolalgorithm(likePID)tosteerthe
robot.Howdoweimplementone?
References
ThePololututorialonBuildingLineFollowingandLineMazeCoursescanbefoundat
http://www.pololu.com/docs/0J22
TheAdvancedLineFollowingwith3pi:PIDControltutorialcanbefoundat
http://www.pololu.com/docs/0J21/7.c
TheParallaxlinefollowingtrack:
http://www.parallax.com/Portals/0/Downloads/docs/prod/robo/scribbler2/Tracks.pdf
Chapter8.ConnectFourDesktopGame
usingRaspberryPi
Inthisproject,wewillbuildadesktopgameenabledbytheRaspberryPi.Wewillbuilda
prototypeusingacardboardbox,amonitor,andaninputcontrolonthecabinetand
implementoptionalspeakersandamarqueeforthegame.Thegamewillmakeuseofthe
python-pygamemodule(agameengineavailableunderGPLlicense:
http://pygame.org/wiki/about).
Missionbriefing
AConnectFourgameisatwo-playergamewheretheobjectiveistoconnectfourcoins
ofthesamecolorinavertical,horizontal,ordiagonalfashion(moreinformationis
availableathttp://en.wikipedia.org/wiki/Connect_Four).Wewillinstallthenecessary
softwarepackagesandaddallthenecessaryaccessoriestomakeadesktopprototype.The
ConnectFourgameinthisprojectisbasedonthebookMakingGameswithPython&
Pygame(http://inventwithpython.com/makinggames.pdf).Thisdesktopgameisagreat
startforpeoplewhoaretryingtogettingstartedwithelectronicsasahobby.
Whenwefinishthisproject,ourcabinetwillbesomethingliketheoneshowninthe
followingimage:
Whyisitawesome?
Ifyouarelikeusandhaveevervisitedthearcadeandwonderedhowmuchfunitwillbe
tobuildagameyourself,thisprojectisforyou.SingleboardcomputerssuchasRaspberry
PiandsitessuchasInstructables(http://www.instructables.com/)onlymakethings
easier,andofcourse,isn’titfuntoconsideradaptingthedesignandleaveyourownstamp
onit?WewillfocusonthePiandhowtouseitforthegameandleavetherestuptowhat
youfindontheInternetandyourownimagination.
Note
Inthisproject,wewillpresentthesubsystemsofwhatcouldpossiblygointobuildinga
minidesktop/tabletoparcadesuchasagameusingRaspberryPi.Wewillnotconcentrate
onpresentingabetteruserinterfaceforthegameoracabinet,butratherwhatittakesto
buildsomethingsimilartoanarcadegame,includinggamelaunch,hardwareinterface,
andsoon.
Yourobjectives
WewillbuildourConnectFourdesktopgamethroughthefollowingactivities:
Installationofthepre-requisites(Missionchecklist)
AhelloworldexamplewiththePython-pygame
Inputcontroldesignforthegame
GettingstartedwiththeConnectFourgame(UI+soundeffects)
AbriefdescriptionoftheConnectFourGameAI
Marqueedesignandcontrol
Settingupoftheswitchesusingacardboardbox
Missionchecklist
OneofthemainprerequisitesforthisprojectistheinstallationofPython-pygame.The
toolcanbeinstalledinasinglestepasfollows:
sudoapt-getinstallpython-pygame
Thisistheonlysoftwaretoolthatwewilluseinthisproject.Werequirethefollowing
itemsfortheconstructionofthearcadecabinet.Wealsoneedthefollowingitemsforthe
project:
Item EstimatedCost
Acardboardbox
MomentaryPressbuttons–Arcadestyle*8
(http://na.suzohapp.com/all_catalogs/pushbuttons/58-9111-L)2.70USDeach
16*32LEDdisplayfromAdafruitorPi-LitedisplayfortheRaspberryPi(optional) USD40USD/31
USD
Amonitorofthereader’schoicewithsignalcabletoconnecttoRaspberryPi 50USD
approximately
RaspberryPi 25USD/35USD
RGBLEDstrip(optional) 10USD
approximately
Helloworldexamplewiththepygame
Inthistask,wewilllearntheusageofpygameforgamedevelopment.Wewillgetstarted
withanexamplethatopensablankwindowandwriteacoupleoflinestomonitorevents
sothatwecanquittheprogramifthewindowisclosed.
Wewillgothroughtheimportantfeaturesofthepygamemodule,whichisnecessaryto
buildourarcadegame,includingplayingsoundsandcontrollingthemenu.
Prepareforliftoff
Asmentionedearlier,thisprojectisbasedonthebookMakingGameswithPython&
Pygame(http://inventwithpython.com/makinggames.pdf).Inthistask,wewillgothrough
selectfeaturesofthepygamemodule.Itisimportantthatyoufamiliarizeyourselfwiththe
differentfeaturesavailableunderthepygamemodule.
Engagethrusters
1. WewillgetstartedbyimportingthemodulesrequiredfortheHelloworldexample.
Wewillimportthepygameandthesysmodule:
importpygame,sys
2. Next,wewillalsoimportpygame.locals,sinceitcontainsseveralconstant
variables:
frompygame.localsimport*
3. Inordertomakeuseofthefunctionsofthepygamemodule,weneedtoinitializethe
module:
pygame.init()
4. Wewillsetthewindowwidthandheightparametersandcreateapygame.Surface
objectthatisstoredinavariablecalledDISPLAYSURF:
DISPLAYSURF=pygame.display.set_mode((400,300))
5. Wewillsetthewindowtitlename:
pygame.display.set_caption('HelloWorld!')
6. Now,wewillrunaloopthatwaitsforeventsinsidethewindowandupdatethe
displaythrougheverycycle.Inthisexample,wedonothaveanythingtobeupdated.
Wewillquittheprogramwhentheuserclosesthewindow:
whileTrue:#maingameloop
foreventinpygame.event.get():
ifevent.type==QUIT:
pygame.quit()
sys.exit()
pygame.display.update()
7. ThisshouldopenupablankwindowtitledHelloWorld.
Playingsoundsusingthepygamemodule
Sincethesoundeffectsformthecruxofanarcadegame,weneedtoknowhowtoplay
soundsusingthepygameplatform.
1. Wewilldeclareasoundobjecttoplaythebeeps.wavfile,availablealongwiththe
downloadsofthisfile.Thefileneedstobecopiedintothesamedirectoryasthe
pythonscriptthatrunsthegameasfollows:
soundObj=pygame.mixer.Sound('beeps.wav')
2. Thesoundcanbeplayedinaloopbycallingtheplay()methodasfollows:
whileTrue:#maingameloop
soundObj.play()
3. Wecanstopplayingthesoundfilebycallingthestop()method.
Buildingmenususingthepygamemodule
1. Wewillneedasimplemenuforourdesktopgame.Wewillmakeuseofthemenu
class(distributedunderGNUGPLv3license)writtenbyScottBarlow.Let’sreview
thesimple_example.pyexample.(http://www.pygame.org/project-MenuClass-
1260-.html.)
2. Inthismenuexample,amenuobjectiscreated;whenamenuoptionisselectedusing
akeyboard,theselectedoptionishighlightedandprintedonaterminalwhenthe
returnkeyispressed.Forexample,whenthedownkeyispressedtoselectLoad
Gameandthereturnkeypressed,theLoadGameoptionisprintedtotheterminal.
3. Let’sdiscusstheparametersthatneedtobepassedasargumentstocreateamenu
object.Accordingtothedocumentationavailablewiththemenuclass,amenuobject
hastobedefinedwiththefollowingparameters:
menu=cMenu(x,y,h_pad,v_pad,orientation,number,
background,buttonList)
Theparametersxandyrefertothelocationoftheoriginofthemenuobjecton
thegamescreen
Theparametersh_padandv_padrefertothespacingbetweenthebuttonsinthe
horizontalandverticaldirections
Theorientationparameterreferstothearrangementofthebuttonsonthe
screen,thatis,'horizontal'or'vertical'
Thenumberparameterreferstothenumberofbuttonsthatcanbe
accommodatedinasinglerow(whenarrangedhorizontally)orinasingle
column(whenarrangedvertically)
Thebackgroundparameterreferstothesurfaceonwhichthemenuhastobe
created
ThebuttonListparameterreferstothelistofbuttonsthatwewantonthe
screen
4. Wewillgetstartedbydeclaringamenuobjectandlistingalltheoptionswewantin
themenu,namely:
menu=cMenu(50,50,20,5,'vertical',100,screen,
[('StartGame',1,None),
('ScoreBoard',2,None),
('Exit',3,None)])
5. Themenuneedstobecenteredonthesurfaceofthescreen:
menu.set_center(True,True)
6. Thetextofthemenubuttonsalsoneedstobealigned:
menu.set_alignment('center','center')
7. Inordertodisplayandupdatethemenuandselectionparameters,asimplestate
machineisused:
state=0
prev_state=1
8. Thepygame.event.wait()methoddetectsanykeyboardormouseeventsand
updatesthecurrentstateaccordingly.
9. Themenuisupdatedbythemethod(duetoakeypressevent/returnkeypress):
pygame.event.post(pygame.event.Event(EVENT_CHANGE_STATE,key=0))
10. Whenthereturnkeyispressedtoselectanoption,theselectedoptionisprintedto
theterminalandthemenuisupdatedbyhighlightingtheselectedoption(inred)by
rect_list,state=menu.update(e,state):
whileTrue:
ifprev_state!=state:
pygame.event.post(pygame.event.Event(EVENT_CHANGE_STATE,key=0))
prev_state=state
e=pygame.event.wait()
ife.type==pygame.KEYDOWNore.type==EVENT_CHANGE_STATE:
ifstate==0:
rect_list,state=menu.update(e,state)
elifstate==1:
print'StartGame!'
state=0
elifstate==2:
print'LoadGame!'
state=0
elifstate==3:
print'Options!'
state=0
else: print'Exit!'
pygame.quit()
sys.exit()
#Quitiftheuserpressestheexitbutton
ife.type==pygame.QUIT:
pygame.quit()
sys.exit()
#Updatethescreen
pygame.display.update()
Objectivecomplete–minidebriefing
Wehavefinishedtestingthepygamemoduleandreviewedasimplemenudesignexample
alongwithtestingtheplayingofsoundsusingthepygamemodule.
GettingstartedwiththeConnectFour
game(UIandsoundeffects)
Inthistask,wewillworkonsomepreliminarytweaksfortheConnectFourgame.Wewill
taketheexamplefromNewGameSourceCode:Fourina
Row,http://inventwithpython.com/blog/2011/06/10/new-game-source-code-four-in-a-row/,
andmakeuseoftheexamplesdiscussedintheprevioustask,namely,playingsoundsand
menudesignandaddthemtotheConnectFourGamePythonscript.
Prepareforliftoff
WeneedtheConnectFourgameexample(fourinarowexample—fourinarow.py)from
thebook.Theexamplecanbedownloadedfromhttp://invpy.com/fourinarowimages.zip.
EngageThrusters
1. Inthisproject,thegameneedstobelaunchedfullscreenassoonasRaspberryPi(that
hasbeensetuptolaunchthedesktopgame)ispoweredup.
2. Thepygame.display.set_modemethodisusedtosetthegametofullscreenwiththe
pygame.FULLSCREENargument.Theresolutionofthegamewillbe(Windowwidthx
Windowheight),inthiscase,640x480pixels:
DISPLAYSURF=pygame.display.set_mode((WINDOWWIDTH,
WINDOWHEIGHT),pygame.FULLSCREEN)
3. Inordertolaunchthegame(thePythonscript:Connect_four.py)afterRaspberryPi
ispoweredup,let’screateashellscriptusingatexteditorwiththefollowing
contentsandcallitstartup.sh:
#!/bin/sh
pythonConnect_four.py
4. Theshellscriptneedstobesavedtothe/home/pilocation.Alternatively,thescript
canbesavedatanyotherlocation.
5. Theshellscripthastobemadeanexecutablefileusingthechmodcommand:
sudochmod755startup.sh
6. Inordertoexecutestartup.shuponboot,the/etc/rc.localfileneedstobe
modified.Inthecommand-lineterminalofRaspberryPi,thefilecanbeopenedusing
atexteditorsuchasnano:
sudonano/etc/rc.local
7. Beforethelastlineofthefile,exit0,thefollowinglineshavetobeadded:
sleep10
cd/home/pi/
/home/pi/startup.sh&
exit0
8. Thescriptisexecutedafterallthekernelmodulesareinitialized.Thescriptis
executedfromthedirectorywherethefileshavebeensaved.
Addingamenuforthegame
Thenextstepistoaddamenuforthegame.Asdiscussedintheprevioustask,wewill
makeofthemenuclassavailableathttp://www.pygame.org/project-MenuClass-
1260-.html
1. ThefirststepistoimportthemenuclassintotheConnectFourgame’sPythonscript:
frommenuimport*
2. Let’screateamenuobjectwiththeStartGameoptionstolaunchthegameandExit
toquitthegame.Wewillintegratethemenufromthefirsttaskofthisproject.We
willgetstartedbyaddingthemenuthatneedstobedrawnonthesurface:
menu=cMenu(50,50,20,5,'vertical',100,DISPLAYSURF,
[('StartGame',1,None),
('Exit',2,None)])
3. Let’ssetthebackgroundofthemenutoabluecolor:
DISPLAYSURF.fill(BGCOLOR)
4. Usingthemenudesigndiscussedintheprevioustask,let’saddalinetolaunchthe
gamewhentheStartGameoptionisselected.Thegameislaunchedbycallingthe
runGame(isFirstGame)method:
ifstate==0:
rect_list,state=menu.update(e,state)
elifstate==1:
runGame(isFirstGame)
isFirstGame=False
state=0
elifstate==2:
print'Exit'
pygame.quit()
sys.exit()
pygame.display.update()
Addingsoundstothegame
Whilethegameisinprogress,thesoundscanbeplayedusingpygame.mixer.Refertothe
followingstepstofindouthowtodothis:
1. Let’sgetstartedbyimportingpygame.mixer:
importpygame.mixer
2. Thisisfollowedbyinitializingpygame.mixer:
pygame.mixer.init()
3. Thesoundsthatwillbeplayedwhenthegameislaunchedorwhilethegameisin
progresshavetobeloaded:
menu_sound=pygame.mixer.Sound('8-bit-circus-music.wav')
moves_sound=pygame.mixer.Sound('ding.wav')
4. WechosetousesoundsfromFreeSounds(https://www.freesound.org).Thesounds
areavailableunderCreativeCommonsLicense.
Tip
Dinghitscanbefoundat
https://www.freesound.org/people/adcbicycle/sounds/13952/and8BitCircusMusic
canbefoundathttps://www.freesound.org/people/bone666138/sounds/198896/.
5. Inthemainmenu,let’splaythe8-bit-circus-musicfileinaninfiniteloop(until
theuserlaunchesagameorexitsthemenu).
menu_sound.play(-1)
6. Theparameter-1indicatesthatthefilesneedtobefiledinaloop.
7. Inordertostopplayingthesound,thestop()methodhastobecalledbefore
launchingthegame:
menu_sound.stop()#stopplayingthesound
runGame(isFirstGame)
8. Thesoundfileisplayedinalooponceagainafterthegameisover.
9. Similarly,thedingsoundisplayedwheneverthegameAI(calledthecomputerinthe
game)ortheplayerhasplayedaturn:
moves_sound.play()#Playdingsound
Objectivecomplete–missiondebriefing
Wehavecompletedthebasictweaksrequiredforthegame.Inthenextstep,wewill
interfacethearcadestylebuttonstothegame.
InterfacinggameinputsusingthePiFace
module
Inthistask,wewillreviewinterfacingthearcadestylebuttons(showninthefollowing
image)toRaspberryPitoplaythegame.Inthistask,wewilljustdiscussthesoftwarepart
ofthecode.
Momentaryarcadepushbuttonswitch
(http://na.suzohapp.com/all_catalogs/pushbuttons/58-9111-L)
WewillmakeuseofthePiFaceinterfaceboardavailableat
http://www.piface.org.uk/products/piface_digital/tointerfacethesebuttonstoRaspberry
Pi.Theboardisastackableadd-onhardwarethatcanbeusedtointerfaceeightinputsand
eightoutputs.ThePiFacecomeswithfourtactileswitchesandwecangetstartedwith
testingtheinputs.
ThemainreasonbehindusingthePiFaceisthatweneedtomonitortheswitchstatesto
determinethereisakeypress.ThePiFacecomeswithanI/Oexpansionoptionandcanbe
accessedthroughtheSPIinterface.Thesefeaturesenablesimplecontrolofthegame
inputs.
Prepareforliftoff
1. RaspberryPi’sSerialPeripheralInterface(SPI)driversneedtoenabledbyeditingthe
/etc/modprobe.d/raspi-blacklist.conffileusingatexteditorsuchasnano:
sudonano/etc/modprobe.d/raspi-blacklist.conf
Thedriverscanbeenabledbyinsertingan#beforethefollowingline:
#blacklistspi-bcm2708
TheSPIdriversneedtobeloadedusingthemodprobecommand:
sudomodprobespi-bcm2708
Thedrivers/toolsrequiredtointerfacewiththePiFacemodulecanbeinstalled
asfollows:
wgethttp://pi.cs.man.ac
.uk/download/old_install.txt
Note
TheinstallationpackagesforthePiFacemoduleareavailableasDebianpackages.
Refertotheinstallationguidefromhttp://www.piface.org.uk/guides/.Ifyouinstall
theDebianpackages,thePythonmoduleimportsandthemethodsusedtoreadthe
inputsmightalsovaryaccordingly.
2. Let’srenamethefileandexecuteit:
mvinstall.txtinstall.sh
chmod+xinstall.sh
./install.sh
3. Oncetherequiredtoolsareinstalled,RaspberryPihastoberestartedusingthe
followingcommand:
sudoreboot
4. OnceRaspberryPihasrestarted,theemulatorthatcomesalongwiththetoolcanbe
tested.TheemulatorenablesyoutotestallinputsandoutputsofthePiFaceinterface.
Theemulatorcanbelaunchedfromthecommand-lineterminalasfollows:
Piface/scripts/piface-emulator
5. Theemulatorinterfacewouldbesomethingliketheoneshowninthefollowing
screenshot:
Engagethrusters
1. Let’stestthebuttonsavailableonthePiFacemoduleusingaPythonscript:
importpiface.pfioaspfio
2. Thepiface.pfiomoduleneedstobeimportedandinitialized:
pfio.init()
3. Theread_input()methodreturnsan8-bitnumberthatrepresentstheinputstatesof
alltheeightbuttons:
whileTrue:
print(pfio.read_input())
4. Eachbitofthe8-bitnumbercorrespondstoadigitalinputonthePiFacemodule.The
followingtableshowstheswitchpositionsthatarerepresentedbybitpositions:
S7 S6 S5 S4 S3 S2 S1 S0
Switchpositionsrepresentedbybitpositions
5. Whenaswitchispressed,aparticularbitissetandthisbitcanbeusedtointerpret
thecolumnpositionoftheConnectFourgame.
6. Forexample,whenS0ispressed,thebit0issetandhencethe8-bitwordvalueis1.
WhenS1ispressed,thebit1issetandthe8-bitwordvalueis2andsoon.
7. WeignorescenarioswhentwoswitchesarepressedatthesametimeastheConnect
Fourgameinvolvesplayingonlyonecolumnatatime.
8. TheConnectFourgamewasdesignedtobeplayedusingamouse.Let’sperform
sometweakstoplayitusingbuttons.Let’sgetstartedbycommentingoutthe
getHumanMove()function.
9. Whenthegameisplayedusingamouse,thecoinisactuallydraggedanddroppedby
theplayer.Thisneedstobesimulatedwhileusingthebuttons.Inordertodoso,let’s
createacopyoftheanimateComputerMoving(board,column)methodandrenameit
asanimatePlayerMoving(board,column).
10. Inthegame,thecomputerplaystheredcolourcoinswhilethehumanplayerplays
withtheblackcolourcoins.So,let’schangethe
animatePlayerMoving(board,column)methodtosimulatethehumanplayer’scoin
movements.
11. ThefollowingarethemodificationsrequiredintheanimatePlayerMovingmethod:
x=REDPILERECT.left
y=REDPILERECT.top
drawBoard(board,{'x':x,'y':y,'color':RED})
animateDroppingToken(board,column,RED)
12. Similarly,themaingameloopalsoneedstobemodifiedtosimulatethehuman
player’sgamemoves:
ifturn==HUMAN:

animatePlayerMoving(mainBoard,0)
makeMove(mainBoard,RED,0)

moves_sound.play()
ifisWinner(mainBoard,RED):
winnerImg=HUMANWINNERIMG
break

turn=COMPUTER#switchtootherplayer'sturn
13. Thenextstepistointerfacethebuttonstothegame.Thefollowingcodeneedstobe
addedunderthehumanplayer’sturn:
#waitforabuttonpress
whilecolumn==0:
column=pfio.read_input()
column_position=0
ifcolumn==1:
column_position=0
elifcolumn==2:
column_position=1
elifcolumn==4:
column_position=2
elifcolumn==8:
column_position=3
elifcolumn==16:
column_position=4
elifcolumn==32:
column_position=5
elifcolumn==64:
column_position=6
14. Weusetheread_input()functiontodetectanybuttonpress.Whenabuttonis
pressed,thereturnedvaluecanbeanywherebetween1and64.Thereturnvalueis
usedtoidentifythecolumnpositionandthecoinmovementissimulated.
15. Similarly,themainmenuofthegameneedstobemodifiedtobecontrolledusing
buttons.Thegameislaunchedwhenbutton1ispressedandtheplayerleavesthe
gamewhenabuttonispressed:
ife.type==EVENT_CHANGE_STATE:
ifstate==0:
rect_list,state=menu.update(e,state)
column=0
whilecolumn==0:
column=pfio.read_input()
pygame.display.update()
ifcolumn==1:
state=1
elifcolumn==2:
state=2
ifstate==1:
menu_sound.stop()
runGame(isFirstGame)
isFirstGame=False
state=0
prev_state=1
elifstate==2:
print'Exit'
pygame.quit()
sys.exit()
Objectivecomplete–minidebriefing
Inthistask,wecompletedthetransferofcontrolstomakeuseofthearcadestylebuttons.
WewillnowproceedtothenextstagewherewewilldiscussthegameAI,marquee
design,andsoon.
AbriefdescriptionoftheConnectFour
GameAI
Inthistask,wewilldiscussthegeneralmechanismofthegame.Wewilldiscussthe
functioncallsused,gameflow,andageneralideaofthegamemechanism.Itwouldbea
goodideatofollowthiscodereviewalongwiththegamecodeavailableinthisproject.
Prepareforliftoff
WearebuildingthisarcadegamebasedonthecodefromMakingGameswithPython&
PygamebyAlSweigart(http://inventwithpython.com/makinggames.pdf).Thisbookisan
interestingreadanditshouldenableustobuildourownarcadegame(notnecessarilythe
ConnectFourgame).
Engagethrusters
1. Let’sgetstartedwithreviewingthegeneralstructureofthegameusingtheflowchart
showninthefollowingdiagram:
2. Thefirststepistoimportthemodulesrequiredtolaunchandplaythegame.This
includesthepygame,pygame.mixer,piface,andserialmodules.
3. Afterimportingtherequisitemodules,gameparameterssuchasgamedifficulty,
boardsizeintermsofwidthandheight,backgroundcolor,windowsize,colorsofthe
computer,andplayercoinsareinitialized.
4. Thegamemenuisinitializedandrenderedonthegamescreentoawaitabuttonpress
bytheplayer.
Maingameloop
1. Whenthestartbuttonispressed,therunGamefunctioniscalledtostartthegame.If
thegameisbeinglaunchedforthefirsttime,theisFirstGamevariableissettotrue.
Thecomputeralwaysplaysfirstfortheveryfirsttimeafterthegameislaunchedand
thefirstturnisrandomizedforconsecutiveplays.
2. Whenanewgameisinitialized,thegetNewBoardmethodiscalledtocreateanempty
boardobjecttogetstartedwiththegame.Allgamemovesbythecomputerandthe
humanplayerarerecordedtothisobject.Thisisusedtodeterminewhetherthereisa
winneraswellasthecomputertodeterminepotentialmovestoplaythegame.
3. Onceweenterthemaingameloop,thegameloopisdividedintotwotasks,the
computerandthehuman’sturn.
4. Whenitistheplayer’sturn,wewaitfortheplayertoplaytheirturnusingthe
buttons.Whenabuttonpressisdetected,usingtheanimatePlayerMovingmethod,a
coindropissimulated.Thegame’sboardobjectisupdatedwiththelatestmove.
5. Thisisfollowedbythecomputer’sturn.ThegetComputerMovemethodcallsthe
getPotentialMovesfunctiontodeterminethebestpossiblemovesavailableforthe
computer’sturn.Then,thecomputer’scoindropissimulatedusingthe
animateComputerMoving()method.
6. ThegameAIrunsacheckaftereachturnhasbeenplayedtodeterminewhetherthe
playerorthecomputerisawinnerusingtheisWinnermethod.
7. Ifeitherofthemhaswonthegame,animagedeclaringthewinnerischosen.The
gamealsocheckswhetherthegamewasatie.Wheneitheroftheearliermentioned
threeeventsoccur,theprogrambreaksoutofthegameloopanddisplaysthewinner
(oratie)andwaitsforthestartbuttoneventtoreturntothemainmenu.
Consequently,thiswillenableyoutostartanewgame.
Objectivecomplete–minidebriefing
Nowthatthecodereviewiscomplete,let’smoveontothenexttasktoimplementa
simplemarqueeandwireuptheinputbuttons.
Marqueedesignandcontrol(optional)
Inthistask,wewillimplementthemarqueecontrolforourarcadegame.Wewilldisplay
informationsuchastheplayer’sturn(whetheritisthecomputerorthehumanplayer’s
turn),thewinnerofthegameattheend(orwhetheritwasatie),orgame-specific
messagesonthemarquee.WewillusethePiLiteLEDMatrixdisplay
(http://shop.ciseco.co.uk/pi-lite-lots-of-leds-for-the-raspberry-pi-1206-red/)thatcanbe
usedtoscrollmessagesacrossthedisplay.
PiLite–Courtesy:TheCisecoPLCwebsite
Prepareforliftoff
ThePiLitedisplaycanbepurchasedfromtheCisecoPLCwebsite
(http://shop.ciseco.co.uk/pi-lite-lots-of-leds-for-the-raspberry-pi-1206-red/).Thedisplay
costsabout33USD.
Oneoftherequirementsistheseriallibrary,whichisrequiredtocontrolthedisplay.It
canbeinstalledasfollows:
sudoapt-getinstallpython-serial
Oncewearedoneinstallingthemodule,weshouldbeabletoimportthemoduleandstart
programmingthemessagesinourgame.TheCisecoPi-LiteGitHubrepositorycomes
withexamplessuchastheBarScrollexample.Itisessentialthatyoudownloadsuch
examplesandtestifthepython-serialmoduleisfunctionallycorrect.
Engagethrusters
1. Wewillgetstartedbyimportingtheserialmoduleandinitializingtheserialport
parameters,includingthebaudrateandportname:
importserial
serialport=serial.Serial()
serialport.baudrate=9600
serialport.timeout=0
serialport.port="/dev/ttyAMA0"
2. Afterinitialization,theserialportisopenedtostartscrollingthemessagesacrossthe
display:
try:
serialport.open()
exceptserial.SerialException,e:
sys.stderr.write("couldnotopenport%r:%s\n"%(port,e))
3. Asanexample,wewilldisplaytheWelcometoConnectFourGamemessageinthe
maingamemenu:
column=pfio.read_input()
serialport.write("WelcometoConnectFourGame")
pygame.display.update()
Objectivecomplete–minidebriefing
Inthistask,wefinishedintegratingtheLEDdisplaytoRaspberryPithatrunsthegame.
Setupoftheswitchesusingacardboard
box
Inthistask,wewilldesignourarcadegamecabinetusingcardboard.Wewillusecable
tiestomountthecomponentsofourarcadegame.Wewillleaveittothereadertodesigna
bettercabinetusingtoolsoftheirchoice.
Prepareforliftoff
Weshouldputtogetheramonitor,RaspberryPi,speakers,andthepushbuttonsusedto
playthegame.Wealsoneedplentyofcardboardtoprototypethedesignofourcabinet.
Engagethrusters
1. Let’sgetstartedwithmountingtheswitches.Theswitcheswillbemountedontoa
cardboardbox.
2. Wegetstartedbymountingthearcadestylepushbuttonsonacardboardbox.The
arcadestylepushbuttonsusedinthisprojectrequireaholethatis1.13inchesin
diameter.Carefullycreatetheholesusingasharpobject.
Note
Donothurtyourselfwhilehandlingsharpobjects.Parentalsupervisionisrequiredif
childrenareworkingonthisproject.
3. Oncethemountingholesarecutoutofthecardboardbox,weneedtomountthe
switchesasshowninthefollowingimage.Theswitchesarelockedinplacebyalock
nutfromthebackside.
4. ThenextstepistointerfacethebuttonstothePiFacemodule.ThePiFacemanual
describesthatthedigitalinputshavepullupresistorsandhencetheswitchescanbe
connectedasshowninthefigurethatfollows:
5. Thecommonterminalofthebuttonneedstobeconnectedtothegroundterminalof
thePiFacemodule.Thenormallyopen(N.O.)terminalofthebuttonisconnectedto
thedigitalinputterminals(S0throughS7)ofthePiFacemodule.
SuggestedinputconnectionsprovidedbythePiFacemanual
6. ThenextstepistoconnectamonitortoRaspberryPi.Thefollowingfigureshowsa
monitorwiththeConnectFourgamelaunchedandtheswitchesmountedontoa
cardboardboxandinterfacedwiththePiFacemodule:
Objectivecomplete–minidebriefing
Inthistask,wefinishedsettingupthedesktopConnectFourgameusingRaspberryPi.
Missionaccomplished
Inthisproject,weaccomplishedthefollowing:
1. WeusedaPythonscriptfortheConnectFourGameandtweakedittoour
requirements.
2. Weimplementedinputcontrolsusingarcadestyleswitches.
3. Wewroteaprogramtocontrolthemarquee.
4. Wealsosetupthingsonacardboardboxtoplaythegame.
Hotshotchallenge
Inthisproject,weperformedcontroloftheinputswitchesasablockingoperation.Can
youfigureouthowtomonitorswitchpresseventsbystartingmultiplethreads?Howcan
weimprovethespeedofthegame?
References
1. MakingGameswithPythonandPygameisavailableat
http://inventwithpython.com/makinggames.pdf.
2. PiFaceGuidescanbefoundathttp://www.piface.org.uk/guides/.
3. Pi-LiteUsers’Guidecanbefoundathttp://openmicros.org/index.php/articles/94-
ciseco-product-documentation/raspberry-pi/280-b040-pi-lite-beginners-guide.
Chapter9.TheRaspberryPi-enabled
Pet/WildlifeMonitor
Inthisproject,wewilldiscusshowtheRaspberryPicaninteractwithotherdevicesona
network.Thisdevicecaneitherbealaptop,anArduino,oranyotherdeviceconnectedto
anetwork.WewillmakeuseofthecapabilityoftheRaspberryPitoactasacontrol
deviceinthenetworkandimplementasimplesolutionthatcansafelyinteractwithour
preciouslittleanimalfriends.
Missionbriefing
Inthisproject,wewilllearntobuildaninteractivepetorwildlife(wecallitwildlifeinthe
contextofanimalsthatarenotdomesticated,forexample,wildcats)monitorthatcanbe
monitoredandcontrolledwithinanetwork(withsomeextraeffortyoushouldbeableto
controlanywhereontheWeb).Thisprojectpresentsthreedifferentpossibilitieswherewe
canmakeuseoftheRaspberryPiincombinationwithotherdevicestobuildaninteractive
deviceforpetsthatdispensetreatstointerfacewithdevicesthateitherinteractwith
pets/feralcats/birds.Thisinteractivedevicecaneitherbeacamerathatcapturesamoment
(forexample,awildbirdcomingandeatingoutofyourbirdfeeder)orarelayboard
activatedtofeedtreatstoouranimalfriendwhileweareawayfromhome.
Note
Thisprojecthasbeenpresentedasanexampletohelpapersonenhancethequalityoflife
fortheiranimalfriends.Thisprojectshouldnotbeconstruedasareplacementofhuman
interactionforouranimalfriends.Wetotallyunderstandthatpetseasethestressinour
livesandthisprojectpresentssomeexamplestomaketheirlivesbetter.
Whyisitawesome?
WearedemonstratingthecapabilitiesoftheRaspberryPiwhilebuildingapetmonitor.
Thiscanbeadoptedinanyapplicationwherethereneedstobeexchangeofinformation
betweendevices.ThisprojectdemonstratestheuseoftheRaspberryPiinthebetterment
ofourlivesfromanotherperspective.Ourpetsandotherferalfriends(forexample,birds
orferalcats)thatvisitusareourfamilymembersandwetryourbesttotakecareofthem.
OurgoalinthisprojectistomaketheRaspberryPidoourjobbetter.
Yourobjectives
Inthisproject,wewillexplorethefollowingtopics:
Installingandtestingthepython-twistedframework
SettingupandtestingSparkCoretointeractwithappliances
InstallingandtestingtheGoogleCoderprojectontheRaspberryPi
Abriefoverviewofabirdfeederthattriggersacamera
Missionchecklist
Forthisproject,wewillneed:
1. ARaspberryPiplusSDcard(atleast4GBinsize)
2. Anyoneofthefollowingboards:
AnArduinoEthernetboard(http://arduino.cc/en/Main/arduinoBoardEthernet)
ASparkCoreboard(https://www.spark.io/)
AnArduinoUnoplusESP8266board(http://www.banggood.com/ESP8266-
Remote-Serial-Port-WIFI-Transceiver-Wireless-Module-p-947259.html)
AfewresistorsandLEDstotestthingsout
AUSBwebcameraortheRapberryPi’scameramodule
Installingandtestingthepython-twisted
framework
Inthistask,wewillreviewthepython-twistedframework
(https://twistedmatrix.com/trac/).TheTwistedframeworkisanopensourceevent-driven
networkenginethatcanbeusedtosendcontrolmessagestootherdevices(forexample,a
petfeedercanbeoperatedusingRaspberryPitodispensesolidfoodtoouranimal
friends).ThemessagingprotocoliscalledAMP(AsynchronousMessagingProtocol)
whichisavailableathttp://amp-protocol.net/.
Prepareforliftoff
TheRaspberryPi(withanSDcardflashedwiththeOSimage)connectedtotheInternetis
neededforthistaskalongwithanArduinoEthernetBoard(oranyoneoftheboards
mentionedearlierinthechecklist.Networkconnectivityisessential).Wewillinstallthe
python-twistedframeworkandreviewaquickexampletoexchangemessagesbetween
ArduinoandtheRaspberryPi.
Engagethrusters
1. Thepython-twistedframeworkcanbeinstalledfromtheterminaloftheRaspberry
Piasfollows:
sudoapt-getinstallpython-twisted
2. Oncetheinstallationiscomplete,itistimetoreviewanexampleofthepython-
twistedframeworktotesttheframework
(http://twistedmatrix.com/documents/current/_downloads/simpleserv.py).
1. Inthistask,wewilllaunchaserverontheRaspberryPiandtrytocommunicate
totheserverwithinthelocalnetwork.
2. Let’smodifytheprecedingexampletobindthepython-twistedservertotheIP
addressofRaspberryPisothatwecanexchangemessageswithotherdeviceson
thenetwork.ThisdevicecaneitherbeanArduinooralaptop.
3. WewillmodifythelistenTCPmethodtobindtheservertotheIPaddressofthe
RaspberryPiandlistentoincomingmessagesattheportaddress,8000.
reactor.listenTCP(8000,factory,50,'192.168.1.89')
4. ThewebservercanbelaunchedbyexecutingaPythonscript.
5. Now,usingalaptopthatisconnectedtothesamenetwork,let’smodifythe
simpleclient.pyscripttosendandreceivemessagestotheserverjust
launchedontheRaspberryPi
(https://twistedmatrix.com/documents/14.0.1/_downloads/simpleclient.py).
6. InordertoconnecttotheserverlaunchedonRaspberryPi,theconnectTCP
methodneedstobemodifiedtoincludetheIPaddressthattheclienthasto
connect:
reactor.connectTCP('192.168.1.89',8000,f)
7. Inthisexample,theRaspberryPiistheserverandthelaptopistheclient.The
serverinthisexampleechoesallincomingmessages.Thus,whentheclient
connectsandsendsamessage,theoutputwillbesomethinglike:
Serversaid:Hello,World!
connectionlost
Connectionlost-goodbye!
3. Nowthatwehaveinstalledtheserver,let’sdiscussasimpleArduinosketchto
interactwiththeserverlaunchedontheRaspberryPi.Thesketchisavailablealong
withthisproject’sdownloads(TwistedFrameworkTest.ino).
1. WewillgetstartedbydeclaringanIPaddressobjectthatincludestheIPaddress
ofRaspberryPi:
//MACAddressoftheArduino
bytemac[]={0x90,0xA2,0xDA,0x0F,0x02,0xFC};
//IPAddressoftheRaspberryPi
IPAddressserver(192,168,1,89);
2. TheArduinoactsasaTCPclientandconnectstotheRaspberryPi:
if(client.connect(server,8000)){
Serial.println("connected");
client.println("Hello,World!");
client.println();
//Letswaitfortheclienttoreadand
//echothemessage
//Note:Asecond'sdelayisabitexcessive
delay(1000);
//Ifthereisaresponsefromtheserver
//echobackthemessage
Serial.println("Serversays:");
while(client.available()){
charc=client.read();
Serial.print(c);
}
client.stop();
Serial.println("ClientDisconnected");
}else{
Serial.println("connectionfailed");
}
3. TheArduinoclientconnectstotheRaspberryPiandtransmitstheHello,
World!message.TheRaspberryPiechoesbackthemessagetotheArduino
client.Ascreenshotoftheserver’sresponsetotheclientisshownasfollows:
InteractionoftheArduinoclientwiththeRaspberryPi
4. WedemonstratedtheabilitytotransmitandreceivemessagesbetweenArduinoand
theRaspberryPi.
Objectivecomplete–minidebriefing
Attheendofthisproject,wewilldiscussmakinguseofthepython-twistedframework
andanArduinoEthernetboardtohelpyoucontrolacameratriggerorremotelydispense
treatsusingapetfeeder.
SettingupandtestingSparkCoreto
interactwithappliances
Inthistask,wewillsetupSparkCore.ItisadevelopmentboardthatmakesbringingWi-
Fitohardwareveryeasy.WewillusetheCoreforthisprojectbecausewelovethe
simplicityofthesetupandoperation.YoucanreadmoreaboutSparkCoreattheofficial
website,https://www.spark.io/.
Youarewelcometouseasimilardeviceofyourchoosing.Agoodalternativewillbeto
useanArduinowithaWi-Fiadapter/shield(forexample,theESP8266Wi-Fimodulecan
befoundathttp://www.seeedstudio.com/wiki/WiFi_Serial_Transceiver_Module)orifyou
prefer,anEthernetshield(asdiscussedintheprevioustaskofthisproject).
Prepareforliftoff
Inthistask,wewillsetuptheSparkCore.PoweruptheSparkCoreusingamicro-USB
cableconnectedtoapowersource(5Vsource).Itcanbepoweredusingabatterypack,a
laptop,ora5VUSBwallwart.Basedonyourprojectneeds,youcanuseabatterypackif
thesensornodeforthepetmonitorhastobeinstalledoutdoors.
TheeasiestwaytoconnecttheSparkCoretoyourWi-Finetworkisthroughaphone
application.ThisandothermechanismsaredetailedontheSparkCorewebsite
(http://docs.spark.io/connect/).WewillsetupourSparkCorebydownloadingthe
applicationontoanAndroidphoneandSamsungGalaxyS5throughtheGooglePlaystore
(https://play.google.com/store/apps/details?id=io.spark.core.android&hl=en).Theapp
searchesforSparkCoresinrangeandifyousupplytheWi-Fipassword,itsendsthecode
totheCore(s)andletsitconnecttoyourWi-Fi.
TheSparkCoreboard
EngageThrusters
WewillwarmupbyimplementingtheLEDexampleonSparkCoreorsomethingsimilar.
ThedocumentationincludescodetoconnectanLEDwitharesistortotheCore
(http://docs.spark.io/examples/).Wedecidedtodosomethingevensimpler.Thereis
alreadyanLEDconnectedtopinD7andwedecidedtoturnthisoneoninstead.
AlltheappsyouneedcanbedownloadedtoacustomwebpageavailableforeachSpark
Corethroughausernameandpassword.
OnceyouhavesetuptheCore,youwillcreateausernameandpassword.Fordifferent
Cores,youwillneeddifferentusernames.Usingthis,youcangototheSparkhomepage
(http://www.spark.io/)andclickontheBuildbutton.Thistakesyoutothehomepageof
thedevelopmentenvironment.
Usingthisdevelopmentenvironment,wecreatedasimpleLEDblinkingapplication:
voidsetup(){
pinMode(7,OUTPUT);
}
voidloop(){
//turntheLEDon(HIGHisthevoltagelevel)
digitalWrite(7,HIGH);
//waitforasecond
delay(1000);
//turntheLEDoffbymakingthevoltageLOW
digitalWrite(7,LOW);
//waitforasecond
delay(1000);
}
Note
TheprecedingcodeiswritteninCprogramminglanguage.Ifyouarejumpingdirectlyto
thisprojectfromotherprojects,wesuggestthatyoufamiliarizeyourselfwiththeArduino
orSparkCoreplatform.Somelearningresourcesareavailableat
https://learn.adafruit.com/search?q=Arduino
Asyoucansee,theappisquitesimple;theappsetsupthepin7asoutput.Theprogram
turnsontheLEDforasecondandturnsitoffforonesecond.
Now,let’sdiscussanexamplethatismoreorlesssimilartotheexamplediscussedinthe
previoustask:
TCPClientclient;
//IPAddressoftheRaspberryPi
byteserver[]={192,168,1,89};
voidsetup()
{
Serial.begin(9600);
while(!Serial.available())SPARK_WLAN_Loop();
delay(1000);
Serial.println("connecting…");
if(client.connect(server,8000)){
Serial.println("connected");
client.println("Hello,World!");
client.println();
//Letswaitfortheclienttoreadand
//echothemessage
//Note:Asecond'sdelayisabitexcessive
delay(1000);
//Ifthereisaresponsefromtheserver
//echobackthemessage
Serial.println("Serversays:");
while(client.available()){
charc=client.read();
Serial.print(c);
}
client.stop();
Serial.println("ClientDisconnected");
}else{
Serial.println("connectionfailed");
}
}
voidloop()
{
//Nothingtodohere
}
Theonlydifferencebetweenthepreviousexampleandthisexampleisthatthelatteruses
theTCPClientclasswhiletheformerusestheEthernetClientclass.
Objectivecomplete–minidebriefing
That’sit.YounowhaveSparkCore,allsetupandreadytogo,withyourusername,and
yourownpagetodownloadappsandcollectandtransmitdatathroughtheCore.
InstallingandtestingtheGoogleCoder
projectontheRaspberryPi
Thisisprobablythesimpleststageoftheprojectasyoushouldbefamiliarwithsettingup
theRaspberryPiforfirstuse.
TheGoogleCoderisatoolreleasedbyGooglethatenablespeopletolearnweb
developmentusingtheRaspberryPi.Itisatoolthatprovidesanintuitivelearningprocess.
AfterinstallingtheGoogleCodertool,wewilltestinterfacingtheGPIOpinsofthe
RaspberryPitothewebinterface.
Prepareforliftoff
WeneedtodownloadtheGoogleCoderimagefromitsrepository.TheGoogleCoder
imageisavailableathttp://googlecreativelab.github.io/coder/.
Engagethrusters
1. Let’sgetstartedwithsettingupGoogleCoderfortheRaspberryPi.Oncetheimage
isdownloaded,wehavetoinstalltheimageontoanSDcard.Ifyouarenotfamiliar
withtheinstallationoftheRaspbianimageontoanSDcard,thefirstprojectofthis
bookisreallyhelpful(wethink!).
2. OncetheRaspberryPiispoweredupafterflashingtheSDcard,MacBookusersmay
launchthetoolfromabrowserbygoingtohttp://coder.local.
3. WindowsusershavetoinstallApple’sBonjourPrintServicesforWindows
(http://support.apple.com/kb/DL999).Onceinstalled,theGoogleCodertoolcanbe
launchedusingaChromebrowser.Now,theGoogleCoderplatformcanbeaccessed
athttp://coder.local.
4. Thesetupprocessisreallysimple.Ifeverythingwentasplanned,weshouldbeable
toseethelandingpageoftheGoogleCoderapplication.
TheGoogleCoderlandingpage
5. Let’stesttheBlinkyLightsexamplefromtheGoogleCoderprojectavailableat
http://googlecreativelab.github.io/coder-projects/projects/blinky_lights/.Theexample
providesdetailedinstruction,includingthecircuitryandcoderequiredtosetupa
switchtoreadbuttonstatesfromtheGPIOinterfaceoftheRaspberryPi(Wechoseto
skiptheexplanationastheexamplealreadyprovidesadetailedelaborationofthe
examplecode).
6. TheBlinkyLightsexampledemonstratestheuseofthenode.jsbasedGPIOhelper
(https://www.npmjs.com/package/pi-gpio)toread/writeGPIOpins.
Objectivecomplete–objectivecomplete
Wewillmakeuseofthethreetasksdiscussedinthisprojecttoputtogetheratriggerthat
comestoeatoutofabirdfeeder.
Abriefoverviewofabirdfeederthat
triggersacamera
Inthistask,wewillsetupabirdfeederwithamotionsensor.Wheneverabirdfliesinto
feedonthegrainsoutofthefeeder,themotionsensoristriggeredtosendamessagetothe
RaspberryPi.AcameramoduleoraUSBcameraisconnectedtotheRaspberryPi,which
capturessomebeautifulmomentsinourbackyard.
SrihariYamanoor(oneoftheauthorsofthisbook)hasanextensivebackyardwherethis
birdfeederhasbeeninstalled.Checkoutthisbook’swebsitetofindoutwhetherwehave
capturedanybeautifulmomentsthusfar!
Prepareforliftoff
Inordertobuildthisinteractivepetfeeder,weneedthefollowingitems:
Apetfeeder.(Availablefromhomeimprovementstores,forexample,HomeDepot,
Lowes,andsoon).
ThePIRsensor(http://www.adafruit.com/product/189).
SparkCoreoranyWi-Fienabledboard.
AUSBbatterypack(http://www.adafruit.com/products/1959).rd
(http://www.adafruit.com/products/64).
RaspberryPiwithaTwistedframeworkinstalled.
ARaspberryPicameramodulewithalensattachment.Forexample,
http://store.cutedigi.com/raspberry-pi-camera-module-5mp-wide-angle-160-degree/.
Engagethrusters
1. ThefirststepinvolvedinprogrammingSparkCoreistodetectthemotionsensor
eventsandpublishthoseresultstoRaspberryPi.
2. ThesensorneedstobeconnectedtoSparkCoremountedonthebreadboardasshown
inthefollowingfigure:
AmotionsensorconnectedtoSparkCore
3. WewillmodifytheexamplefromAdafruitthatprintsthemotionsensorevents
(https://learn.adafruit.com/pir-passive-infrared-proximity-motion-sensor/using-a-pir).
4. Wheneveramotioneventisdetected,weneedtosendanalerttothepython-
twistedserverlaunchedonRaspberryPi:
if(client.connect(server,8000)){
Serial.println("MotionDetected");
client.println("MotionDetected");
client.println();
//Letswaitfortheclienttoreadand
//echothemessage
//Note:Asecond'sdelayisabitexcessive
delay(1000);
client.stop();
Serial.println("ClientDisconnected");
}else{
Serial.println("connectionfailed");
}
5. Inordertotakepicturesofthebirdfeederwhenthereisanincomingmotion
detectionevent,thecamerahastobeinterfacedtotheRaspberryPiasdemonstrated
inthevideoprovidedbytheRaspberryPiFoundation
(https://www.youtube.com/watch?v=GImeVqHQzsE).
6. Inordertotriggeracameratotakeasnapshotusingthepython-twistedserver,we
needthepicameramodule(https://pypi.python.org/pypi/picamera).Itcanbeinstalled
asfollows:
sudoapt-getinstallpython-picamera
7. Let’smodifythepython-twistedexample,simpleserv.py,toimportthepicamera
anddatetimemodules(tonamethepicturescapturedbythecamerausinga
timestamp).
8. IftheincomingmessageisMotionDetected,wewilltakeapictureandnamethe
fileusingatimestamp.
9. Inthecallbackmethod,DataReceived,let’scaptureanimage:
withpicamera.PiCamera()ascamera:
camera.start_preview()
time.sleep(2)
camera.capture('img{timestamp:%Y-%m-%d-%H-%M}.jpg')
Abirdtrigger
Objectivecomplete–minidebriefing
Checkoutthisbook’swebsitetolookattheRaspberryPiandSparkSensorsetupthatis
usedtotakepictures.Thisisreallyhelpfultolearnmoreaboutthebirdsinyour
neighborhood.
Alternativesandprojectideastoconsider
1. Inthisproject,wediscussedtheexamplesusingtheSparkCoreandtheArduino
Ethernetboard.AnotherexampletoconsideristheEPS8266module,whichis
availableathttp://www.banggood.com/buy/Esp8266.html,andcostsabout3USD.
Refertothisbook’swebsiteforsettinguptheESP8266moduletoemulatethese
examples.
2. InProject4,ChristmasLightSequencer,weusedaPowerSwitchTailandarelay
boardexampletocontroldecorativeappliances.Similarly,wecanusethemtocontrol
automaticpetfeederstodispensetreats.
Missionaccomplished
Inthisproject,weinterfacedbuiltasmallecosystemofdevicesthatweremonitoredby
theRaspberryPi.Weusedthoseexamplestobuildabirdfeeder!
Hotshotchallenge
Inthisproject,wediscussedinterfacingasensortotakepicturesofbirdsthatcometofeed
fromthebirdfeeder.Isitpossibletouploadthevideofeedtosomewherethat’ssecure
overtheInternet?Howdowedothis?
Chapter10.RaspberryPiPersonalHealth
Monitor
Inthisproject,wewilldiscussimplementingasolutionwhereRaspberryPiactsasa
personalhealthmonitor.Wewouldliketodedicatethisprojecttoallthepeoplewhohave
beendiagnosedwithtype2diabetesoranyotherlifestylediseases.Thisprojectpresents
sometricksforthosediagnosedwithsuchlifestylediseases.
Note
Pleasedonotconsiderthisprojectasanalternativetoexistingtreatmentandpractices.
Thisproject’strickswillhelpyouleadabetterlife.Forexample,yourRaspberryPican
remindyoutotakeyourprescribedmedication(ifany).
Missionbriefing
Inthisproject,wewillbuildsomesolutionstoaddresscommonproblemsencounteredby
peoplewithlifestylediseases.SimilartoProject6,RaspberryPiasaPersonalAssistant,
thisprojectpresentsdifferenttipsandtrickstoleadabetterlifeineachtask.Wewill
discussexampleswhereapersoncanbuildasimplewebservertostorehis/herdailyvital
healthparameters(forexample,bloodpressure,bloodoxygensaturationlevels(SpO2),
andsoon).Also,theservercanhelpapersontoremainphysicallyactivethroughtheday,
provideaquickrecapofthee-mailparser,providetheeventremindertoolfromProject6,
RaspberryPiasaPersonalAssistanttoremindapersonaboutupcomingappointments,
refillhis/herprescriptions,andsoon.
Whyisitawesome?
Wedecidedtowritethisprojectbasedonthepersonalexperienceofoneoftheauthors’
familymember.Itisquitestressfulforapersonwhenhe/sheisdiagnosedwithachronic
conditionssuchastype2diabetes.Thepersonissubjectedtostressfulconditionsrelated
tochangeindailyfoodhabits,developingahabitofconsumingmedicationeveryday,and
beingmindfulofwhathe/sheeatseverydaywhilstensuringthattheircriticalhealth
parametersareintact.Itisobviouslydifficulttoacceptasuddenchange,andthisproject
presentssomeoptionstomitigatesuchdifficultiesandbringtheperson’shealthbackon
track.
YourHotshotobjectives
Inthisproject,wewillreviewthefollowingexamples:
Settingupawebservertorecordhealthparameters
AsimplephysicalexercisetoolusingRaspberryPi
Settingupane-mailfeedparsertorefillaprescriptionaswellasremindtheuser
aboutanupcomingdoctor’sappointment
Asimpletoolthatremindsapersontotakehis/herpills
Missionchecklist
Itwouldbegreattohavethefollowingcomponentsforthisproject:
ARaspberryPialongwithanSDcard(ofatleast4GBinsize)thathasbeenflashed
withanimageandrequisitepowercable.
AnArduinoEthernetboard(http://arduino.cc/en/Main/arduinoBoardEthernet).This
iscompletelyoptional.
Atactileswitch,resistors(10K),andapiezoelectricbuzzer(allthesecomponentsare
availablefromRadioShack).
ItwouldbegreattohavetwoRaspberryPiboardstobuildthephysicalexercisetool
usingRaspberryPi.
Settingupawebservertorecordhealth
parameters
Inthistask,wewillbuildasimplewebserverthatcanbeusedtomaintaincriticalhealth
parameters.Let’sconsiderascenariowhereapersonisdiagnosedwithhighblood
pressure.Thedoctorasksthepatienttorecordhis/hervitalhealthparameterssuchas
pulse,oxygenlevel,orbloodpressure.Forthissituation,wewillbuildasimplewebpage
thatrecordsthedataandstoresitinaCSVfile.
Prepareforliftoff
WewillbeusingtheFlaskframework(http://Flask.pocoo.org/)todeploythewebserver
onRaspberryPi.WemadeuseoftheFlaskframeworkinProject4,ChristmasLight
Sequencer.JustincaseyouskippedthroughProject4,ChristmasLightSequencer,a
Pythonpackagemanagersuchaspiporeasy_installisrequiredtoinstalltheFlask
framework:
sudoapt-getinstallpython-pip
AftertheinstallationofthePythonpackagemanageriscomplete,theFlaskframework
maybeinstalledasfollows:
sudopipinstallFlask
Engagethrusters
1. WewillmodifythisbasicFlaskframeworkexample
(http://runnable.com/UhLMQLffO1YSAADK/handle-a-post-request-in-Flask-for-
python)totakeinputfromabrowser:
Inthefrontendofthewebserver,let’screatetextboxesinthe
form_submit.htmlfilewherewecanenterthebloodpressure,oxygen
saturationlevels,andpulsedata.Thelandingpagewilllookliketheoneshown
inthefollowingfigure(whenopenedinabrowser):
Theformusedtorecordvitalhealthparameters
InthePythonscriptthatlaunchesthewebserver,wereadthesubmitted
parametersandwritethemtoaCSVfilealongwithatimestamp:
@app.route('/',methods=['POST'])
defrecord():
#recordallthedatafromtheform
bloodPressure=request.form['BloodPressure']
SpO2=request.form['SpO2']
pulse=request.form['pulse']
#beforewritingtoacsvfile,logtimestamps
date=datetime.today().strftime('%Y-%m-%d')
time=datetime.now().strftime('%H:%M:%S')
logfile=open('static\\comments.csv','a')
logfile.write(",".join([date,time,bloodPressure,SpO2,
pulse,'\n']))
logfile.close()
return
render_template('form_action.html',date=date,time=time,bloodPressur
e=bloodPressure,SpO2=SpO2,pulse=pulse
Oncewe’redonewritingtotheCSVfile,weredirectthesubmittedformtoa
pagethatdisplaystherecordedvaluesalongwiththetimestamp(asshowninthe
followingfigure):
Thepagedisplayedaftertheresultsarerecorded
2. ItispossibletoviewtherecordeddataonthewebpagebyreadingtheCSVfile.We
leavethisforyoutofigureout(lookatthisbook’swebsitefortheanswer).
Objectivecomplete–minidebriefing
WebuiltasimpleFlask-framework-basedwebservertorecordvitalhealthparameters
usingRaspberryPi.Itispossibletoe-mailthedataatregularintervalsusingthesmtp
moduleinPython.
AsimpleexercisetoolusingtheRaspberry
Pi
Inthistask,wewillreviewafunexamplethatenablesapersontobephysicallyactive
every60minutes.
Prepareforliftoff
ThisexampleisbasedontheTwistedframeworkdiscussedinthepreviousproject.It
wouldbegreattohavetwoRaspberryPiboards(setupwiththeSDcardimagesand
poweredup)oranArduinoEthernetboard.Alaptopthatisconnectedtothesamenetwork
astheRaspberryPiisjustassufficient.
IfyoumissedinstallingtheTwistedframeworkinthepreviousproject,theTwisted
frameworkcanbeinstalledasfollows:
sudoapt-getinstallpython-twisted
Note
IftheseconddeviceisaRaspberryPioralaptopthatrunsLinux,Mac,orWindows
operatingsystems,theTwistedframeworkneedstobeinstalledontheseconddeviceas
well.
Engagethrusters
1. Let’sperformaquickreviewofwhatwewillbuildinthisproject:
Let’sconsidertwodevicesthatcanbeconnectedtoanetwork.Oneofthe
devicesisaRaspberryPiwhiletheotherdevicecouldeitherbeanArduinoora
RaspberryPi.Wewillreviewthecoderequiredtobuildthistoolforbothcases.
Thesedeviceshavetobeinstalledattwoextremecornersinsideahouse.This
canbedifferentfloorsofthehouseorthefarthestcornersofthehouse.
AbuzzerandabuttonwillbeconnectedtoaRaspberryPi.
Thebuzzerwouldgooffevery60minutesononeofthedevices.Someonehas
towalkuptothedeviceandturnoffthebuzzerbypressingabutton.
Thisenablesapersontogetsomephysicalactivitybywalkingbackandforth
betweenthetwodevices(assumingtheRaspberryPidevicesareinstalledfaraway
fromthepersonintheinterestofgainingsomephysicalactivity).
Note
Thisexampleisjustamotivationaltoolandacasualreminderfortheconcerned
persontoremainphysicallyactive.
2. ThebuzzerandtheswitchareconnectedtotheRaspberryPiasshowninthe
followingdiagram:
AbuttonandbuzzerschematiccreatedusingFritzing
TheprecedingbreadboardrepresentationshowsanAdafruitPiCobblermounted
onabreadboard.RefertoProject4,ChristmasLightSequencer,forapictorial
representationofhowthePiCobblerneedstobeconnectedtotheRaspberryPi.
GPIO#25oftheRaspberryPiisconnectedtothebaseoftheNPNtransistor,
BC547.Thetransistor’scollectorpinisconnectedtothenegativeterminalofthe
buzzer.Theotherendofthebuzzerisconnectedto5V.Theemitterpinofthe
transistorisconnectedtotheground.Thetransistoractsasaswitchandturnson
thebuzzerwhenthebasepinissettohigh.
GPIO#18oftheRaspberryPiispulledupto3.3Vandatactileswitchis
connectedtotheGPIOswitch.Theotherendoftheswitchisconnectedtothe
ground.
3. Let’sperformaquickreviewofthetwistedservercodethatrunsontheRaspberryPi.
Similartothepreviousproject,thisexampleisalsoasimplemodificationofthe
Twistedframeworkexample,simpleserver
(http://twistedmatrix.com/documents/current/_downloads/simpleserv.py).
Let’screateaclassthattakescareofsettingoffthebuzzerwhenthereisan
incomingmessage:
#Declareinputsandoutputs.
GPIO.setmode(GPIO.BCM)
GPIO.setup(18,GPIO.IN)
GPIO.setup(25,GPIO.OUT)
GPIO.setwarnings(False)
classAsyncTask:
def__init__(self):
self.run_state=True
#avoidingthechannelargumentthrowsanerror
defterminate(self,channel):
self.run_state=False
defadd_callback(self):
GPIO.add_event_detect(18,GPIO.FALLING,callback=self.terminate)
defrun(self):
whileself.run_state==True:
GPIO.output(25,GPIO.HIGH)
time.sleep(1)
GPIO.output(25,GPIO.LOW)
time.sleep(1)
GPIO.remove_event_detect(18)
IntheAsyncTaskclass,thebuzzercanbesetoffbytriggeringaseparatethread
tocalltherunfunction.Thissetsoffthebuzzerwithaone-secondinterval.
Theadd_callbackmethodisusedtoturnoffthebuzzerwhenthebuttonis
pressed.Theadd_event_detectmethodwaitsforthestateofGPIO#18to
changefromhightolow.Thisturnsoffthebuzzerbysettingrun_stateto
False.Whileexitingtheinfiniteloop,weremovethecallbackfunctionsusing
theremove_event_detectmethod.
Whenaclient(Arduino,laptop,oranotherRaspberryPi)sendsamessagetothe
server,thethreadisinitializedandacallbackfunctionisregisteredasfollows:
async_task=AsyncTask()
async_task.add_callback()
thread=Thread(target=async_task.run,args=())
thread.start()
Tosummarize,anincomingmessagetriggersthebuzzerandapersonhasto
walktotheRaspberryPi’slocationtoturnoffthebuzzer.
4. IftheclientdevicethatsendsamessagetotheRaspberryPiisalaptopthatrunsa
Linux,Mac,orWindowsoperatingsystemortheRaspberryPi,itissufficienttorun
thesimpleclient.pyexampleaftermodifyingthecodetochangetheserveraddress
tothatoftheRaspberryPi
(https://twistedmatrix.com/documents/14.0.1/_downloads/simpleclient.py).
5. Intheprecedingexample,wedemonstrateasinglecycletosetoffthebuzzer.This
canberepeatedincyclesof60minutesusingabatchscript(inaWindows
environment)orashellscript(LinuxorMacenvironment).
6. IfthedeviceisanArduino,EthernetClienthastobeinitializedandconnectedto
theRaspberryPitosendatestmessage.Thiscanberepeatedina60-minutecycle:
Serial.println("connecting…");
if(client.connect(server,8000)){
Serial.println("connected");
client.println("Hello,World!");
client.println();
//Letswaitfortheclienttoreadand
//echothemessage
//Note:Asecond'sdelayisabitexcessive
delay(1000);
//Ifthereisaresponsefromtheserver
//echobackthemessage
Serial.println("Serversays:");
while(client.available()){
charc=client.read();
Serial.print(c);
}
client.stop();
Serial.println("ClientDisconnected");
}else{
Serial.println("connectionfailed");
}
Aminiprojectidea
ItwillbefuntoinstallanumberofRaspberryPiboardsinthesamenetworkand
implementanasynchronousmessagingprotocol.Thisprotocolcansetoffbuzzersasa
chainreactiontoencouragemorephysicalactivity.Pleasenotethatthismayannoyother
membersofthehousehold.
Objectivecomplete–minidebriefing
Wediscussedatoolthatcanannoyapersontoremainphysicallyactive.
Settingupane-mailfeedparsertorefilla
prescriptionaswellasremindtheuser
aboutanupcomingdoctor’sappointment
Inthistask,wewilldiscusssettingupanLEDtoalertapersonaboutanincominge-mail
torefillaprescriptionorwhenthereisanupcomingdoctor’sappointment.
JustincaseyouskippedthroughProject6,RaspberryPiasaPersonalAssistant,the
python-feedparsertoolandthepython-gdatatoolhavetobeinstalled:
sudoapt-getinstallpython-feedparser
sudoapt-getinstallpython-gdata
Note
Thistaskissimilartothee-mailnotifierwesetupinProject5,InternetofThings
Example–AnE-mailAlertWaterFountain.Wewilljustdiscussaminormodificationto
blinkanLEDwhenthereisane-mailintheinboxtorefillaprescription.
Engagethrusters
1. Wewillgetstartedbycheckingforanynewincominge-mails:
email=feedparser.parse(proto+username+":"+password+"@"+server+path)
2. Let’sassumetheprescriptionrefillremindere-mailsubjectiscalledWalgreens.We
williterativelycheckthrougheachentryandtriggeranLEDalert:
formailinemail.entries:
ifmail.title=="Walgreens":
async_task=AsyncTask()
async_task.add_callback()
thread=Thread(target=async_task.run,args=())
thread.start()
AnasynchronoustaskcanbetriggeredtoblinkanLEDuntilthealertis
acknowledgedbypressingabutton.Thecircuitryissimilartotheonediscussed
intheprevioustask.
3. Thisenablesapersontorespondtoane-mailandrefillhis/herprescriptionwhen
necessary.Thispreventsarefillremindergettingburiedamonge-mailsandenables
thepersontokeepatabonprescriptiondelays.
Settingupareminderfordoctor’sappointments
ThisisalsosimilartotheeventnotifierthatwediscussedinProject6,RaspberryPiasa
PersonalAssistant.Let’sassumethatalldoctor’sappointmentsaresavedinthecalendar
asDoctor'sappointment.Itispossibletoprominentlydisplayallupcomingdoctor’s
appointmentsasfollows:
fori,an_eventinenumerate(feed.entry):
ifan_event.title.text=="Doctor'sappointment":
print'\t%s.%s'%(i,an_event.title.text,)
Intheprecedingexample,wearejustprintingittoaconsole.Youcanperhapsmakeuse
ofadisplay,forexample,anOLEDdisplaythatiscontrolledviaaserialport,anddisplay
itataprominentlocation.
Objectivecomplete–minidebriefing
Inthistask,wecompletedthesetupofane-mailnotifiertorefillprescriptionsanda
reminderforanupcomingdoctor’sappointment.
Asimpletoolthatremindsapersonto
takehis/herpills
Inthistask,wewillbuildasimpletoolthatremindsapersontotakehis/herpillsontime.
Thecircuitryrequiredforthisexampleissimilartotheexamplesdiscussedintheprevious
tasks.Wearediscussingthisexamplebecauseitisdifficultforsomeonetodevelopahabit
oftakingtheirmedicationontime.Itiscriticalthatpeopleidentifiedwithchronic
conditionsdonotmisstheirprescriptionschedule.
Prepareforliftoff
WeextensivelydiscussedinterfacingthebuzzertoaRaspberryPiintheprevioustask.
It’llbenicetohaveanenclosureforthepillboxreminder.Anexampleofapillreminderis
availablefrominstructablesathttp://www.instructables.com/id/The-Pill-Reminder/.We
willonlydiscusshowtotriggerthebuzzerataselectedtimeoftheday.
Engagethrusters
Let’ssayapersonhastotakehis/herprescribedpillsat9:30inthemorning;abuzzercan
betriggeredusingthedatetimemoduleinPython:
whileTrue:
t=datetime.datetime.now()
ift.hour==9andt.minute==30:
async_task=AsyncTask()
async_task.add_callback()
thread=Thread(target=async_task.run,args=())
thread.start()
break
Otherprojectideas
Similartotheexamplesdiscussedearlier,itisalsopossibletosetreminderstosync
pedometerdata,gotothegym,orevenrecordthehealthparametersdiscussedearlierin
thisproject.
Objectivecomplete–minidebriefing
Inthistask,wecompletedthepillboxremindersetuptohelpustakeourmedicationon
time.
Missionaccomplished
Inthisproject,wediscussedseveralexamplesofRaspberryPiactingasapersonalhealth
monitorusingasimpleconcept.Thiscanbeadaptedfordifferentscenariosaccordingto
yourcreativity.
Hotshotchallenge
HowcanweuseRaspberryPitoenhancethelivesofseniorcitizens?
Chapter11.HomeAutomationusing
RaspberryPi
Inthisproject,wewillreviewsomeautomationexamplesusingRaspberryPi.These
examplescanbeconsideredasprojectsthatcanbeexecutedoveraweekend.
Missionbriefing
Inthisproject,wewilldiscussdifferentoptionsavailableforautomationathomeusing
RaspberryPi.Theexamplesuseasimilarconcept(moreorless)andyoucanpickthe
tasksofyourchoiceandturnyourhomeintoasmarthome.
Whyisitawesome?
AquickwebsearchyieldsalotofprojectsrelatedtohomeautomationusingRaspberryPi.
Wehavetriedtokeepthisprojectuniquebyensuringthatitissimpleenoughtobe
executedoveraweekend(thoughsomeexamplesmightappearrepetitiveifyouhavebeen
readingthroughtheprojectsintheircorrectorder),whileincorporatingfeedbackfrom
projectsavailableallovertheWeb.
Yourobjectives
Wewilldiscussthefollowingexamplesinthisproject:
Asimpleexamplethatcontrolslimitedindoorandoutdoorlightingintheevening
Acustomarywebserverexample
Turningonalawnsprinkleronlywhenthereisanorainforecast!
Missionchecklist
Thefollowinghardwareitemsarerequiredforthisproject:
1. RaspberryPialongwiththenecessaryaccessories(anSDcard—atleast4GBinsize,
1AUSBpowersupply,andamicro-USBpowercable).
2. PowerSwitchTailIIfromAdafruitthatisavailableat
http://www.adafruit.com/product/268.
3. Ethernetcables/Wi-Fiadapter(optional,neededtoconnecttheRaspberryPitoa
network).
4. Sensorsofyourchoice.Forexample,Soilmoisturesensor.
5. Generalhardwarefromthelocalstore(thisdependsuponthereader’sproject
requirements).
6. ArduinoEthernetBoard(optional)availableat
http://arduino.cc/en/Main/arduinoBoardEthernet.
Wewillinstallthesoftwareprerequisitesaswerevieweachexampleinthisproject.
Asimpleexamplethatcontrolslimited
indoorandoutdoorlightingintheevening
Let’sconsiderascenariowhereapersonlivesinaneighborhoodthatisnotsowelllit.In
winter,thetemperaturesareusuallyextremeincitiessuchasChicagoandthesunusually
setsaround5p.m.Thepoorlylitneighborhoodalongwiththecoldweathermakesit
difficultforapersontoentertheirhome.
Wewillbuildasimplesolutionthatturnsonalight(thatcanbeeitheranoutdooror
indoorhallwaylight)thatspeedsuptheprocessofenteringabuilding.
Prepareforliftoff
Inthisexample,wewillmakeuseofPowerSwitchTail2(soldbyAdafruitIndustries:
http://www.adafruit.com/product/268)toturnon/offthelights.
ThePowerswitchtailisratedtocontrolappliancesratedtooperateat110Vanditcan
switchresistiveloadsupto15A.ThePowerSwitchTail2canswitchon/offappliances
whenitisactivatedbya3-12VDCsignal.
OnemainadvantageofusingthePowerSwitchTail2isthatitisopto-isolated(opto-
isolationensuresthatRaspberryPiisprotectedfromanytransientvoltageswhileturning
on/offthelights)andprovidesasafealternativetointerfacingelectricalappliancesto
RaspberryPi.TheimagebelowshowsaPowerSwitchTail2availablefrom
http://www.adafruit.com.
PowertailswitchII–Photocourtesy:adafruit.com
Softwareprerequisites
WewillneedtherepositorytoolGit.Thiscanbeinstalledasfollows:
sudoapt-getgit-core
Engagethrusters
1. PowerSwitchTail2’sdatasheet
(http://www.adafruit.com/datasheets/PST%20II%20product%20insert.pdf)providesa
schematicdescriptionoftheinternalcircuitryofPowerSwitchTail2.
PowerSwitchTail2isconnectedtoRaspberryPiasshowninthefollowing
figure.Thein+terminaloftheswitchisconnectedtotheGPIO#17of
RaspberryPi,whilethein-terminalisconnectedtothegroundpinofRaspberry
Pi.
PowerSwitchTail2’sinterfacetoRaspberryPi
ThepowercordtothelightingequipmentneedstobeconnectedtoPowerSwitch
Tail2.
Note
Itisassumedthatyouarefamiliarwithsomeminorrewiringtoconnect
indoor/outdoorlightingappliances.Priortrainingisrequiredtohandlesuchelectrical
hardware.Ifyouarenotfamiliarwithhandlingrewiring,itisbesttoconnectanoff-
the-shelfelectricalappliance.
2. Let’sreviewthecodeforanexamplewherethelightsneedtobeturnedonbetween
5:30p.m.and10:45p.m.everyday.
WegetstartedbycreatingUnixtimestampsforthestartandendtimes(Unix
timestampsreferstothetimeelapsedsinceJanuary1,1970inseconds.More
informationisavailableathttp://en.wikipedia.org/wiki/Unix_time):
#Getcurrenttime
now=datetime.datetime.now()

#Createdatetimeobjects
startTime=datetime.datetime(now.year,now.month,now.day,17,30,0)
endTime=datetime.datetime(now.year,now.month,now.day,22,45,0)

#Createunixtimestamps
unixStart=(startTime-
datetime.datetime(1970,1,1)).total_seconds()
unixEnd=(endTime-datetime.datetime(1970,1,1)).total_seconds()
unixNow=(now-datetime.datetime(1970,1,1)).total_seconds()
TheUnixtimestampsareusedtocheckwhetheritistimetoturnon/offthe
appliances:
if(unixStart<=unixNow<=unixEnd):
GPIO.output(25,GPIO.HIGH)
while(unixStart<=unixNow<=unixEnd):
now=datetime.datetime.now()
unixNow=(now-
datetime.datetime(1970,1,1,0,0,0)).total_seconds()
print"Triggered",now.hour,":",now.minute,":",now.second
sleep(1)
GPIO.output(25,GPIO.LOW)
Objectivecomplete–minidebriefing
Yay!Wearedonewithasimpleautomationtaskofkeepingthelightsonatagiventime
periodeveryday.
Alternativesolutionsandsomeprojectideastoconsider
1. IfitisnotpossibletoinstallRaspberryPirightnexttothepowertailswitch,itis
possibletointerfacethePowerSwitchTail2toanArduinoEthernetboardand
controlledbyRaspberryPiusingtheTwistedframeworkexample(hint:refertothe
examplesfromthepreviousproject,Project10,RaspberryPiPersonalHealth
Monitor).ThisenablesyoutocontrolanetworkofdevicesusingRaspberryPi.
2. OnealternativetoconsiderifitisnotpossibletopurchaseaPowerSwitchTail2—
SparkFunhasanexcellenttutorialonbuildingacontrollableACpoweroutlet
(https://www.sparkfun.com/tutorials/119).
3. Inthisexample,weassumedthatthelightswillbeturnedonbetweentheselected
timeslots.Itisalsopossibletoturnonthelightsbydeterminingthesunsettime.
NOAAprovidesinformationoncalculatingsunsettimes,whichisavailableat
http://www.esrl.noaa.gov/gmd/grad/solcalc/calcdetails.html.
4. Anotheralternativetoturning/offlightingappliances—itwouldbeagreatideato
makecoffeeeverydayusingPowerSwitchTail2.Ifthecoffeemakerisfilledwith
waterandthecoffeepods/filterarereplaced,thecoffeemakerwillbeturnedonatthe
chosentime!Wewillhaveourcoffeereadyrightaftergettingoutofbed.
Note
PowerSwitchTail2isdesignedforresistiveloadsandespeciallyforlimiteduse.Do
nottrytouseitwithheavyinductiveloadssuchasamotor.Thistoolisstrictly
recommendedforthosewhoareknowledgeablewiththefundamentalsofelectrical
engineering.
Acustomarywebserverexample
AnyhomeautomationprojectusingRaspberryPiyieldsalotofexamplesthatinvolves
buildingawebserverthatcontrolsapplianceswithinalocalnetworkthattakescareof
securingtheplaceusingelectromechanicallocks.Wewillbuildasimplewebserverthat
canbeusedtoturnoffanLEDfromawebpage.Thisconceptcanbeexpandedtocontrol
multipleappliancesandreadsensordatafromtheGPIOinterfaceofRaspberryPi.
Note
ThistaskismeantforabsolutebeginnerswhoarenotfamiliarwithPythonweb
frameworktools.Wearediscussingthisexampleconsideringsomereadersmightjump
righttoProject11,HomeAutomationUsingRaspberryPi.
Prepareforliftoff
WewillbebuildingawebserverusingaFlaskframework(http://flask.pocoo.org/).The
Flaskframeworkcanbeinstalledasfollows:
sudoapt-getinstallpython-pip
sudopipinstallFlask
Engagethrusters
1. Thefirstpartissettingupthelandingpage.Whenauserenterstheaddressofthe
webserver,thewebpagewouldbesomethinglikewhatisshowninthefollowing
screenshot.TheHTMLpageconsistsofasinglebuttoncalledSampleButton.
Aflaskframework-basedwebserver
2. Whenabuttonisclicked,theincomingPOSTrequestisusedtoswitchthestatesof
theLEDfromONtoOFFandviceversa:
@app.route('/',methods=['POST'])
defrecord():
#recordallthedatafromtheform
globalstate
ifstate==False:
state=True
else:
state=False
GPIO.output(25,state)
returnrender_template('form_submit.html')
3. ThewebservercanbelaunchedfromtheIPaddressofRaspberryPi.Thewebpage
shouldbeaccessiblefromhttp://192.168.1.76:75:
#Runtheapp:)
if__name__=='__main__':
app.run(
host="0.0.0.0",
port=int("75")
)\
Thewebserverexampleisavailablealongwiththisproject.Checkthisbook’swebsitefor
moreexamples.
Objectivecomplete–minidebriefing
Usingthesimpleconceptexplainedearlier,itispossibletocontrolanyappliance(by
interfacingsomecontroldevicesuchasthepowerswitchtailtoRaspberryPi’sGPIO
pins).Itisalsopossibletoreadsensorstatesaswellastrackanyspecialinformation.For
example,itispossibletotrackthestatusofapackagethatisexpectedtobedelivered.
USPSprovidesstatusofshipmentsthatcanbedisplayedonthewebpage(formore
informationonAPIs,checkouthttps://www.usps.com/business/web-tools-
apis/welcome.htm).
Inalltheseexamples,wereviewedcontrolappliancesusingRaspberryPiwithinalocal
network.Inthelatertaskofthisproject,wewillreviewcontrollingthedevicefrom
anywhereovertheInternet.
Turningonalawnsprinkleronlywhen
thereisnorainforecast!
ThisexamplewasinspiredbyacommentonanarticlerelatedtoHomeAutomationusing
RaspberryPi.Thecommentermentioned:
TheonlyhomeautomationthatI’minterestedin(andstillhaven’tseen)issomething
that’llturnoffmylawnsprinklersifit’srainedacertainamountintheprecedingdaysor
ifit’srainingonthedaythatthesprinklersareprogrammedtogoon.
Wedecidedtowhipupaquickexamplethatwouldturnonthesprinklerwhenitisnot
goingtorainonaparticularday.
Prepareforliftoff
Inordertochecktheweatherforecast,weneedtomakethepython-weather-apilibrary
(thelibraryisdistributedwithMITlicense).WewillmakeuseoftheNOAAAPI.The
librarycanbedownloadedusingthewgetcommand:
wgethttps://launchpad.net/python-weather-api/trunk/0.3.8/+download/pywapi-
0.3.8.tar.gz
Thesourcefilesareavailableinacompressedfolder.Thecontentsofthecompressedfile
canbeextractedasfollows:
tar–xvzfpywapi-0.3.8.tar.gz
Onceextracted,thelibrarycanbeinstalledasfollows:
pythonsetup.pybuild
sudopythonsetup.pyinstall
WealsoneedaflowcontrolvalvesimilartothisonesoldonSparkFunavailableat
https://www.sparkfun.com/products/10456.
Engagethrusters
1. NOAA(http://www.weather.gov/)providesweatherdatageneratedfromtheweather
stationssituatedindifferentcities.Eachcity’sweatherstationhasauniquefour-letter
code.Forexample,Chicago,Illinois’codeisKORD.Wewillmakeuseofthisfour-
lettercodetoretrievetheweatherforecastforacity.
2. Theweatherdataisretrievedusingthepywapilibraryasfollows:
defmain():
pp=pprint.PrettyPrinter(indent=4)
whileTrue:
result=pywapi.get_weather_from_noaa('KORD')
pp.pprint(result['weather'])
sleep(10)
3. Wewillturnonthesprinkleronlyiftheweatherforecast(availableundertheweather
keyword)isanythingotherthanRain,LightRain,orThunderstorm:
if(result['weather']!='LightRain'or
result['weather']!='Rain'or
result['weather']!='Thunderstorm'):
GPIO.output(25,GPIO.HIGH)
4. Thesprinklercanbeturnedonusingatransistorswitchingcircuitandarelay.(Ifyou
arenotfamiliarwithtransistorswitchingcircuitandrelays,Project4,Christmas
LightSequencerprovidesinformationaboutatransistorswitchingcircuitinextensive
detail).
5. Ithasnotbeendemonstratedherebutthepywapimoduleneedstobeusedin
conjunctionwiththedatetimemoduletoturnonthesprinkleratselectedtimesof
day.
Objectivecomplete–minidebriefing
IfitisnotpossibletointerfacethesolenoidvalvedirectlytoRaspberryPi,asthesolenoid
valvecanonlybeinterfacedtoanArduinoandcontrolledusingthepython-twisted
framework.
InstatessuchasCaliforniawheretherearesometimesseveredroughts,itiscommon
practicetosavewaterfromdrainpipesusingbarrels.Thepywapimodulecanbeusedto
replacethebarrelsifthereisanupcomingrainforecast.
GainingremoteaccesstoyourRaspberryPito
controlappliances
ItispossibletoremotelylogintoRaspberryPiusingSSH(SecureShell).An
organizationcalledWeaved(http://www.weaved.com/)providesthecapabilitiestologin.
Thetutorialavailablefromhttps://www.juicypi.io/access-your-raspberry-pi-anywhere-in-
the-world-using-weaved/providesdetailedinstructionstoinstalltherequisitetools.
ThisenablesyoutocontrolthedevicesinterfacedtoRaspberryPi.
Someprojectideastoconsider
Inhouseswithlonghallways,itisnotalwayspossibletohearthedoorbellringfrom
thefarendofthehouse.Itispossibletoplaceaforcesensitiveresistor
(https://www.sparkfun.com/products/9375)totrackanyvisitorstothehouse.
Likewise,itispossibletotrackpackagesleftonthedoormat.
InProject6,RaspberryPiasaPersonalAssistant(thepersonalassistantproject),we
builtasmallenclosuretokeeptrackofkeysusingareedswitch.Asimilarconcept
canbeusedtotrackitemsusingareedswitch.
ThereisawirelessprotocolcalledZ-Wavethatwasspecificallydesignedforhome
automationpurposes.RaspberryPicanbeturnedintoacontrolcentretowirelessly
controlappliancesusingtheZ-Wavemodules.Raspberrycompatiblemodulesare
availableforsaleathttp://razberry.z-wave.me/(checkoutthisbook’ssiteforsome
examples).
InProject5,InternetofThingsExample–AnE-mailAlertWaterFountain,webuilt
awebserverthatcansetcolorsoftheRGBLEDstrip.Therearesomeinteresting
ideastodecorateourhomeswiththeseRGBLEDstrips
(http://www.usledsupply.com/shop/install/project-photos-and-ideas.html).
GEApplianceshascomeupwithaninterestingdevelopmenttoolthatcanbeusedto
controlproductsfromGE.ThistoolincombinationwithRaspberryPi(running
Twistedserver)canbeusedtocontrolGEproductsinsomeone’shome.Inthefuture,
allGEapplianceswillbecapableofbeingconnectedtoasmartdevicesnetwork.
Missionaccomplished
Inthisproject,welookedintodifferentsolutionsthatcanbeimplementedusingRaspberry
Pioveraweekend.Wereviewedsomebasicexamplesthatcanbepossiblytweakedto
turnahomeintoasmartone.
Chapter12.UsingaRaspberryPifor
ScienceandEducation
Inthisproject,wewillreviewsomeexamplesofhowtheRaspberryPicanbeusedto
educateourselves.WewillreviewexamplesofhowtousetheRaspberryPiforself-
improvementoreducatingchildreninthefieldofscience.
Missionbriefing
Inthisproject,wewillreviewsomeexamplestodemonstratehowtheRaspberryPicanbe
usedtoeducateourselvesforself-improvementordemonstrateasimplephysics
experiment.
Whyisitawesome?
ThePi,asyouhaveseeninthelastfewprojects,offersyouimmensefunctionality,and
wasbasicallydesignedtoencouragelearningcomputerscienceatanaffordablecost.As
wehaveseen,thepossibilitiesofbuildinggadgetsusingtheRaspberryPiareendless,
makingthisanawesomesegueintoself-improvementandscience.
YourHotshotobjectives
Inthisproject,wewilldiscussthefollowingexamples:
ImprovingyourvocabularyusingtheRaspberryPi
RaspberryPiandKhanAcademy
BuildingasciencefairexhibitusingtheRaspberryPi
Improvingyourvocabularyusingthe
RaspberryPi
Asanexampleofself-improvementusingtheRaspberryPi,wewillimplementan
examplethatretrievesthewordofthedayusingtheWordnikAPI
(https://www.wordnik.com/).
Prepareforliftoff
WeneedtoinstalltheWordnikPythonclient(distributedundertheApacheLicense)
availableasaPythonpackage:
sudopipinstallwordnik
ThenextstepistoobtainanAPIkeytomakeuseoftheAPI.Thiscanbeobtainedby
registeringforanaccountwithWordnikandrequestinganAPIkey
(http://developer.wordnik.com/).
Oncetheinstallationiscomplete,itistimetoreviewtheexample.
Note
TheWordnikAPIismerelybeingdemonstratedasanexample.RefertotheAPItermsof
agreementtodeterminehowtheAPIcanbeusedinacommercialapplication.
Engagethrusters
1. Let’sreviewanexamplethatfetchesthewordofthedayusingtheWordnikAPI.The
firststepistoimporttheWordnikPythonclient:
fromwordnikimport*
2. ThenextstepistocreateaclientthatinitializestheAPItoaccessthewordlist:
url='http://api.wordnik.com/v4'
key='APIKey'
client=swagger.ApiClient(key,url)
3. ThenextstepistoinitializetheWordnikAPIandretrievethewordoftheday:
words=WordsApi.WordsApi(client)
example=words.getWordOfTheDay()
4. ThereturnedobjectisaWordOfTheDayobject(https://github.com/wordnik/wordnik-
python/blob/master/wordnik/models/WordOfTheDay.py).Let’sprinttheword,
definition,andthepublisheddate:
string='TheWordoftheDayis'+example.word+'.'
printstring
string='Definition:'+example.definitions[0].text
printstring
string='Date='+example.publishDate.strftime("%D")
printstring
5. TheoutputofthisPythonscriptissomethingliketheoneshownhere:
TheWordoftheDayisasportation.
Definition:Thefeloniousremovalofgoodsfromtheplacewherethey
weredeposited.
Date=01/19/15
6. Now,thiswordofthedaycanbedisplayedonascreenatsomeprominentlocation
usingaGUItoolsuchasTkinter(http://zetcode.com/gui/tkinter/)andupdatedevery
24hours.Refertothisbook’swebsiteforsomeideas.
Objectivecomplete–minidebriefing
Inthistask,wereviewedanexampleofhowtouseyourRaspberryPiforself-
improvement;similarly,thereareAPIsfromothersourcesthatprovideaquoteoftheday,
jokeoftheday,andsoon.
RaspberryPiandKhanAcademy
Inthistask,wewillreviewanexamplethatenablesworkingonmathexercisesfromKhan
Academy(https://www.khanacademy.org/).KhanAcademyisanon-profiteducational
organizationthatprovidesfreelearningresourcesforvarioussubjects,includingmathand
computerscience.Inthisexample,wewillhostasimplewebserveronaRaspberryPi
thathoststheexercisesfromKhanAcademylocally.Thisenablescustomizationofthe
learningtoolstotheuser’sneeds.Forexample,itcanbehostedonanetworkthatisnot
connectedtotheInternetandwecancustomizecontentfromKhanAcademytohelp
someoneimproveontheirmathskills.
ThefirststepistoclonetherepositoryonaRaspberry
gitclonehttps://github.com/Khan/khan-exercises
Oncetherepositoryiscloned,itistimetolaunchthewebserver!
Note
Theexercisesaredistributedunderanon-commerciallicensewhilethewebserver
frameworkisdistributedunderanMITlicense.Youmustbeawareofthelicense
agreementswhentryingtomakeuseofresourcesfromKhanAcademy.
Thelaunchoftheserverinvolvesasinglestep.Afterswitchingtothekhan-exercises
directory,thewebservercanbelaunchedasfollows:
python–mSimpleHTTPServer
ThewebservercanbeaccessedonalocalnetworkbyusingyourRaspberryPi’sIP
addressfromabrowserusinghttp://192.168.1.98:8000/khan-exercises/exercises/.
ThefollowingisascreenshotofthewebserverhostedonaRaspberryPi:
KhanAcademyexercisesonalocalserver
Someideastoconsider
WeusethiswebservertosolvepuzzlesusingtheRaspberryPi.Itcanbeusefultosharpen
yourmentalacuitywhilekillingtime.
Buildingasciencefairexhibitusingthe
RaspberryPi
Inthistask,wewillbuildasimplephysicsexperimentcontrolledbytheRaspberryPi.
Thiscanbeusedtoexplainhowthingssuchasasolarpanel,windmill,andsoonwork.In
thisexample,wewillbuildawindmillexperimentthatcanpossiblybeusedasa
demonstrativeexhibitatasciencefair.
Prepareforliftoff
Weneedawindmillgeneratorkitfromahobbystore(forexample,
http://amzn.com/B0016PBH9Q).Thekitneedstobeputtogetherleavingtheleadsofthe
DCmotorexposed.
Engagethrusters
1. TheDCmotorofthewindenergykitneedstobeinterfacedtotheRaspberryPi
GPIOpinasshowninthefollowingFritzingschematic:
AFritzingschematicshowingtheinterfaceofaDCmotorandabuttonforcontrol
2. SincetheDCmotorisinterfacedtoyourRaspberryPi’sGPIO#18,itcanbeturned
on(wearemakinguseoftheRPi.GPIOlibraries;refertopreviousprojectsifyouare
notfamiliarwithRPi.GPIO):
importRPi.GPIOasGPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(18,GPIO.OUT)
GPIO.output(25,GPIO.HIGH)
3. Whenavisitorattheexhibitionwouldliketoknowhowawindmillworks,an
instructionalaudiorecording(thedownloadavailablewiththisprojectmerelyplaysa
testMP3file)canbeplayedatthepressofabuttonasfollows:
defmy_callback(channel):
os.system('mpg321recording.mp3&')
GPIO.add_event_detect(25,GPIO.FALLING,callback=my_callback)
4. ThefollowingimageshowsawindmillgeneratorkitinterfacedtoaRaspberryPi:
Awindmillgeneratorkit
Objectivecomplete–minidebriefing
YourRaspberryPicanalsobeusedtobuildsomethingthatteststheskillsofpeopleata
sciencefairortoprovideentertainment(raffledraw,puzzle,andsoon).
Somesimpleeducationalexperimentsusingthe
RaspberryPi
1. Asoftwaretoolthatalertswhentheinternationalspacestationfliesbyyourvicinity
canbefoundathttp://issabove.com/iss-above-and-the-raspberry-pi/.
2. AcollectionofscientificexperimentarticlesusingtheRaspberryPicanbefoundat
http://www.raspberrypi.org/the-raspberry-pi-in-scientific-research/.
3. ScratchisagraphicalprogrammingtooldevelopedbyMITtomotivatechildrento
getstartedwithlearningtoprogram.Scratchcanbefoundat
http://www.raspberrypi.org/tag/scratch/.
Hotshotchallenge
Isitpossibletobuildareceptionistrobotliketheoneshownatthefollowinglinkusing
theRaspberryPi?Refertohttp://roboceptionist.org/project.htmformoreinformation.
Chapter13.TipsandTricks
Inthisproject,wewilldiscusstipsandtrickstoovercomeanyproblemsonemight
encounterwithRaspberryPi.Wealsoprovideprojectideas,generalinformation,anda
dissectionoftheRaspberryPiitself.
Missionbriefing
Inthisbook,wediscusseddifferentprojects,spanningdifferentdifficultylevels.Before
wrappingupthisbook,wewouldliketoshareourexperienceaboutthechallengeswe
encounteredandsharesometipsandresourcestoovercomesituationsthatyoumight
encounterandpossiblesolutionsforthem.Wewillalsodiscusspossibleprojectideasthat
youcantrytoimplementoveraweekend.Wewillgointoeachaspectbriefly.
Whyisitawesome?
Thisprojectsharestipsandtricks,providesprojectideas,anddiscussessolutionsto
problemsgenerallyencounteredinDIYprojects.
Yourobjectives
Inthisproject,wewilldiscussthefollowing:
SettingupRaspberryPiasadevelopmentplatform
Projectideasthatcanbeimplementedoveraweekend
RemotelyloggingintoRaspberryPifromanywhereontheInternet
ProblemsthatmightbeencounteredwhileusingRaspberryPi
Cooladd-onhardwaresourcesdevelopedfortheRaspberryPiplatform
UsefulresourcesforRaspberryPi
Missionchecklist
Haveyourcuriosity,attentionandpassionattheready.
SettingupRaspberryPiasadevelopment
platform
RaspberryPiiscurrentlythemostbasic,idealhardwareenvironmenttogetstartedwith
learningtocodeinaparticularlanguageoradvancedsystemsdevelopment.
#1–SimpletrickforPythondevelopmentvia
remotelogin
Whilewritingthisbook,wefounditconvenienttowritePythonscriptsonour
laptop/desktop,copythemovertoRaspberryPi,andtestthemviaremotelogin.Thiswas
especiallyusefulwhenwehadRaspberryPicontrollinginterfacedtotoolsonaChristmas
tree.ItisdifficulttosetupamonitorandkeyboardforRaspberryPiandworkfromthere.
WeusedWinSCP(http://winscp.net/eng/index.php—sincewewereusingalaptoprunning
Windows)totransferfilesfromthelaptoptoRaspberryPi.Then,weusedthePuTTY
SSHclient(http://www.putty.org/)foraremotelogintoRaspberryPiandtestedthe
scripts:
InordertoremotelylogintoRaspberryPiortransferfilesusingWinSCP,OpenSSH
isrequired.TheRaspbianWheezyimagecomeswithSSHinstalledandenabledby
default.
Let’sloginafterdownloadingandinstallingWinSCP.Theusernamewouldbepiand
thepasswordraspberry(unlessyou’vechangedthedefaultpassword).
TheWinSCPloginwindow
Thenextstepisittolocatethefilestobetransferredonthelocalmachineaswellas
identifyingthefolderwherethefilesneedtobecopiedtoRaspberryPi.Thefileson
thelocalmachinearelocatedontheleft-handside,whilethefilesonRaspberryPi
arelocatedontheright-handsideofthewindow.
TransferringfilesusingWinSCP
Oncethefilesaretransferred,wecanmakeuseofPuTTYforremoteloginto
RaspberryPi.Asshowninthefollowingfigure,wecanconnecttotheRaspberryPi
usingtheIPaddressofRaspberryPiandloginusingthecredentialsprovidedearlier.
ConnectingtoRaspberryPiusingPuTTY
#2WebdevelopmentusingGoogleCoder
GooglereleasedanopensourcetoolbasedontheRaspberryPiplatformcalledCoder
(http://googlecreativelab.github.io/coder/).WemadeuseoftheGoogleCodertoolin
Project9,TheRaspberryPi-enabledPet/WildlifeMonitor.GoogleCoderisanopen
sourcetooltolearnwebdevelopment,butitsusehasexpandedandasanopensourcetool,
itisreadyforyourprojectsastheneedarises.Forexample,itispossibletobuildaweb
interfacetoread/writetotheGPIOinterfaceofRaspberryPi(forexample,
http://googlecreativelab.github.io/coder-projects/projects/blinky_lights/).
#3AdafruitOccidentalis
AdafruitIndustriesreleasedaversionofRaspbian,Occidentalisthatenabledeasier
hardwaredevelopmentasitfeatureddriversforallstandardcommunicationprotocols.
AdafruitIndustriesalsoreleasedaweb-baseddevelopmenttoolthatcomeswithseveral
Pythonexamples.
#4JavaDevelopmentusingtheRaspberryPi
OraclehasreleasedatutorialsetthatteachesJavadevelopmentusingRaspberryPi.This
includestutorialsoninterfacepressuresensorsandwritingJavacodetoreadbarometric
pressuredatafromthesensorviatheI2Cinterface.
#5TheThingboxproject
TheThingBoxProject(http://thethingbox.io/)isatoolthatallowsyoutoenableprojects
thatarerelatedtotheInternetofThingsonRaspberryPi.Itisasetoftoolsthatallowsyou
tointerfacesensorsandappliancestotheInternet,availableasanOSimagethatcanbe
flashedontoanSDcardandrunonRaspberryPi.Oneofthetoolsavailablewiththe
ThingBoxProjectisNode-RED(http://nodered.org).TheNode-REDtool(shownin
followingscreenshot),infact,isagraphicalinterfacetoolthateliminatestheneedforyou
toprogramtocontrolthedevicesconnectedtoyourPi.Asthenamesuggests,any
applicationisbuiltusingnodesandthecontrolflowisshownbyconnectedwires.
AHelloworldprojectusingNode-RED
RemotelyloggingintheRaspberryPi
fromanywhereontheInternet
AcompanycalledWeaved(http://www.weaved.com/)hasreleasedatoolthatisstillunder
betatestingwhilewritingthisbook.ItenablesyoutoremotelylogintoRaspberryPithat
isconnectedtotheInternetfromanywhereontheWeb(apartfromalocalnetwork).There
isalsoatutorialtoinstallandusethetool(https://www.juicypi.io/access-your-raspberry-
pi-anywhere-in-the-world-using-weaved/).Thisenablesremotecontrol/datacollection.
Problemsthatmightbeencounteredwhile
usingRaspberryPi
ThefollowingaresomeproblemsweencounteredwhileweworkedonRaspberryPi.
SDcardcorruption
WeencounteredSDcardcorruptionswhileworkingwithRaspberryPi.Insomecases,we
hadtodiscardtheSDcardbutinothercases,wewereabletorecovertheSDcardusing
AdvancedPartitionScannerWizardandre-imagetheSDcard.
Sometimesthefailureoccursbecausethereisapowerfailurewhilethecardisstillbeing
writtento.Suchfailuresareunavoidableoverthelifeofyourprojects.Hereareafew
waystoavoidSDcardcorruption:
PowerdownyourPiproperlyafteruse
ChargeyourbatterypacksandmakesurePihasaconstantpowersupplyatalltimes
BesuretobuygoodqualitySDcardsandaswitheverythingelsedigital,havebackups.
Powerissues
WeencounteredissuesrelatedtothepowerdrawofRaspberryPi.Wehadlittlesuccess
withthingssuchasabatterypack(wewereabletogetitworkingusinga2700mAh
batterypack).Asyoumaybeaware,RaspberryPineedsa1A,5VUSBpowersupply.
DevicespoweredbyUSB
SomedevicessuchasawebcamcannotbeconnecteddirectlytotheRaspberryPianda
USBhubmaybenecessarytoconnectsuchdevices.
Cooladd-onhardwaresourcesdeveloped
fortheRaspberryPiplatform
Thereareseveralproductsandadd-onhardwaredevelopedspecificallyforRaspberryPi.
MostofthemaredesignedspecificallyforRaspberryPi.Someofthemareavailable
throughDIYproductsellerssuchasSparkfunandAdafruitIndustries.Mostproductsare
developedthroughcrowdfundingsitessuchasKickstarterandIndiegogo.Wemadeour
bestefforttointroduceanewpieceofhardwareineachproject.Asimplewebsearch
shouldpopupanewproductforaspecificapplication.
TheRaspberryPimodelBversusB+,modelA
versusA+
TheRaspberryPimodelA+andB+hasmoreGPIOpinsthanthemodelAandB.The
modelB+hastwomoreUSBportswhilemodelA+consumeslesspowerthanthemodel
A.Hence,itispossibleuseapoweroverEthernetmodule(PoE).Checkout
http://www.silvertel.com/component/content/article/22-latest-news/304-raspberry-pi-
poe.htmlformoreinformation.
IfyouownaRaspberryPiB+butthehardwareyouowniscompatiblewithRaspberryPi
modelB,youcanmakeuseofa40pinto26pinadapteravailablefromAdafruit
Industries(https://www.adafruit.com/products/1986).
Projectideasthatcanbeimplemented
overaweekend
Besideswhatyouhaveseensofarinthisbook,thereareseveralcoolprojectsthatcanbe
implementedinaweekorless.Theseincludethefollowing:
AsmartalarmclockbasedonRaspberryPi,withfeaturessuchascustomalarm
sounds,period,snoozeoptions,theabilitytoreportweatherconditions,alertyou
abouttoday’sto-dolist,andmuchmore.
Homeautomationandhomesurveillancesystems,acamerathatworksonmotion,
VOCalarms,moodlighting,lightingcontrols,andsoon.
Asensornetwork,wiredorwireless,tomonitorvariousparametersaroundyour
house—temperature,plants,pets,andothers.
Adigitalphotoframenetworkthatchangesimagesacrossmanyframes,depending
onthetimeofthedayandsoon.
SeasonalprojectssuchaslightsforDiwali,Hanukah,orChristmas.
UsefulresourcesfortheRaspberryPi
Inthissection,wewilldiscussusefulresourcesthatareavailableforRaspberryPi.While
thisbookcancovereveryaspectoftheprojectsdevelopedinthisbook,wewilldefinitely
runintotrouble.Let’slookatsomeusercommunitiesthatcantrytoaddressourproblem.
RaspberryPiFoundation’sforums:
TheRaspberryPiFoundation(http://www.raspberrypi.org/forums/)hasmaintaineda
forumsinceitsinception.Thisforumprovidesanswerstoavastspectrumofquestions
thatyoumayhave.Italsooffersanopportunitytodirectlyinteractwiththecreatorsof
RaspberryPi.
RaspberryPiStackExchange:
Atthetimeofwritingthisbook,theRaspberryPiStackExchange
(http://raspberrypi.stackexchange.com/)wasinthepublicbetatestingmode.Ifthissite
passesthebetatestingphase,itshouldalsocontainapoolofusefulresources.
Element14’sRaspberryPicommunity:
TheElement14website(http://www.element14.com/community/community/raspberry-pi)
hostsaseriesofblogpostsfromRaspberryPiuserswhohavebuiltanecosystemof
gadgetssurroundingRaspberryPi.Thecommunitywebpagehostscontestsregularlyin
ordertoexhibitthetalentofRaspberryPienthusiastsandDIYhobbyists.Thecommunity
webpagealsohasauserforumtoexchangeinformation,askquestionsrelatedtoorder
status,andsoon.
Missionaccomplished
Inthisproject,wediscussedcertainprojectideas,tips,andtricksandproblemsyoumight
encounterwhileworkingonaprojectusingRaspberryPi.Theauthorssincerelyhopethat
youhaveenjoyedthisbook.
Index
A
AdafruitCobbler
about/PythondevelopmentontheWebIDE
AdafruitIndustries
URL/Prepareforliftoff,TheRaspberryPimodelBversusB+,modelAversus
A+
AdafruitOccidentalis
about/#3AdafruitOccidentalis
AdafruitWebIDE
Occidentalis/Whyisitawesome?
AdvancedIPScanner
URL/SetupofaremoteloginintotheRaspberryPi
AI,ConnectFourgame
about/AbriefdescriptionoftheConnectFourGameAI,Engagethrusters
maingameloop/Maingameloop
AMP(AsynchronousMessagingProtocol)
URL/Installingandtestingthepython-twistedframework
Arduino
about/Whyisitawesome?
distributors/WherecanyoubuyanArduino?
programming,withRaspberryPi/ProgrammingtheArduinousingthe
RaspberryPi,Engagethrusters
Arduinoacknowledgement,forcontrollingsignal
controlflow,forweatherclock/Controlflowfortheweatherclock
temperaturedata/Temperaturedata
RGBLEDstripcontrol/ControloftheRGBLEDstrip
steppermotorcontrol/Controlofstepperviaserialport
weatherforecastposition,programming/Programmingtheweatherforecast
position
8x8matrixcontrol/8x8matrixcontrol
BlinkMcontrol/BlinkMcontrol
ArduinoEthernetBoard
URL/Missionchecklist
ArduinoEthernetboard
URL/Missionchecklist
ArduinoIDE
installing/InstallingtheArduinoIDE,Objectivecomplete–minidebriefing
ArduinoRaspberryPiinterfaceproject
about/Missionbriefing
features/Whyisitawesome?
objectives/YourHotshotobjectives
checklist/Missionchecklist
ArduinoIDE,installing/InstallingtheArduinoIDE,Objectivecomplete–mini
debriefing
Arduino,programmingwithRaspberryPi/ProgrammingtheArduinousingthe
RaspberryPi,Engagethrusters
RaspberryPiAlaMode/RaspberryPiAlaMode,Engagethrusters
WeasleyWeatherClock/TheWeasleyweatherclock,Engagethrusters,
Objectivecomplete–minidebriefing
steppermotor,controllingwithArduino/Controllingthestepperusingthe
Arduino,Prepareforliftoff,Engagethrusters
RGBLEDstrip,controllingwithArduino/ControllingtheRGBLEDStrip
usingtheArduino,Prepareforliftoff,Engagethrusters
I2Ccommunication,Arduinoused/I2CCommunicationusingtheArduino
(optional)
serialportcommunication,withRaspberryPi/Serialportcommunicationwith
theRaspberryPi
ArduinoUnoplusESP8266board
URL/Missionchecklist
Atmelseries/Whyisitawesome?
audiodevice
interfacing/Interfaceofanaudiodevice
AutodeskInventor/Prepareforliftoff
B
8BitCircusMusic
URL/Addingsoundstothegame
BarScrollexample/Prepareforliftoff
BCMGPIOmode
URL/Engagethrusters
birdfeeder
settingup,withmotionsensor/Prepareforliftoff,Engagethrusters,Objective
complete–minidebriefing
requisites/Prepareforliftoff
BlinkM/IntroductiontothePiCrust–aprototypingplatformfortheRaspberryPi
about/TestanddebuggingexamplesusingtheWebIDE
URL,fordatasheet/Engagethrusters
BonjourPrintServicesdrivers
URL/SetupofaremoteloginintotheRaspberryPi
C
cannyedgedetectiontechnique
about/Engagethrusters
chassis
designing/Designingthechassisforthelinefollowingrobot,Engagethrusters
Christmaslightsequencerproject
about/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
decorativeappliances,interfacing/InterfacethedevicestotheRaspberryPi,
Prepareforliftoff
digitallyaddressableRGBmatrix,settingup/Settingupthedigitally
addressableRGBmatrix,Prepareforliftoff,AnArduino-basedcontrol
audiodevice,interfacing/Interfaceofanaudiodevice
webserver,installing/Installingthewebserver,Engagethrusters
webserver,interfacing/Interfacingthewebserver,Engagethrusters,Objective
complete–minidebriefing
circadianlightingproject
URL/Engagethrusters
CisecoPi-Litegithubrepository/Prepareforliftoff
CMake
about/Missionchecklist
command-lineinterface-basedapproach
about/Acommand-lineinterface-basedapproach
SDcardmountpoint,identifying/IdentifyingtheSDcardmountpoint
SDcard,unmounting/UnmounttheSDcard
SDcard,flashing/FlashtheSDcard
components,RaspberryPi
about/FeaturesofaRaspberryPi
ConnectFourdesktopgame
about/Missionbriefing
referencelink/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
Helloworldexample,withpygame/Helloworldexamplewiththepygame
UI/GettingstartedwiththeConnectFourgame(UIandsoundeffects),Engage
Thrusters
gameinputs,interfacingwithPiFacemodule/Interfacinggameinputsusingthe
PiFacemodule,Prepareforliftoff,Engagethrusters
AI/AbriefdescriptionoftheConnectFourGameAI
marqueecontrol/Marqueedesignandcontrol(optional)
switches,settingupwithcardboardbox/Setupoftheswitchesusinga
cardboardbox
D
datainterpretation,linefollowingrobot/Engagethrusters
DCmotor
controlling,withH-Bridge/Prepareforliftoff
devices
interfacing,toRaspberryPi/InterfacethedevicestotheRaspberryPi,Prepare
forliftoff,Engagethrusters
digitallyaddressableRGBmatrix
settingup/SettingupthedigitallyaddressableRGBmatrix,Prepareforliftoff
working/Howdoesitwork?
Dinghits
URL/Addingsoundstothegame
dishmonitor
assembling/Settinguptheassemblyforthedishmonitor,Engagethrusters,
Objectivecomplete–minidebriefing
DIYtabletopfountainkit
requistes/Prepareforliftoff
about/Engagethrusters
E
e-mailalerts
settingup,infountain/Setupofthee-mailalertsinthefountain,Engage
thrusters
e-mailfeedparser
settingup/Settingupthee-mailfeedparser,Engagethrusters,Settingupane-
mailfeedparsertorefillaprescriptionaswellasremindtheuseraboutan
upcomingdoctor’sappointment,Engagethrusters
settingup,forreminders/Settinguptheparserforremindersandevents,
Engagethrusters
settingup,forevents/Settinguptheparserforremindersandevents,Engage
thrusters
doctorappointmentsreminder,settingup/Settingupareminderfordoctor’s
appointments
electricaltape
used,forbuildingtrack/Useelectricaltapeandbuildatrack
Element14
URL/Element14’sRaspberryPicommunity:
about/Element14’sRaspberryPicommunity:
enclosuredesign,personalassistant
URL/Prepareforliftoff
F
Flaskframework
installing/InstallationoftheFlaskframework,Engagethrusters,Prepareforlift
off,Engagethrusters
URL/Prepareforliftoff
Flaskframeworkexample
URL/Engagethrusters
FreeSounds
URL/Addingsoundstothegame
G
gameinputs,ConnectFourdesktopgame
interfacing/InterfacinggameinputsusingthePiFacemodule,Prepareforlift
off,Engagethrusters
GoogleCoder
about/InstallingandtestingtheGoogleCoderprojectontheRaspberryPi
URL/Prepareforliftoff,#2WebdevelopmentusingGoogleCoder
settingup/Engagethrusters
used,forwebdevelopment/#2WebdevelopmentusingGoogleCoder
GPIO
settingup/Missionbriefing,SettinguptheGPIO,Engagethrusters
features/Whyisitawesome?
objectives/YourHotshotobjectives
checklist/Missionchecklist
requisites/Huntingandgathering
libraries,installing/InstallingGPIOlibraries
libraryinstallation,verifying/GPIOprogrammingusingPython
H
Helloworldexample,ConnectFourdesktopgame
about/Helloworldexamplewiththepygame
pygamemodule,features/Prepareforliftoff
pygamemodule,using/Engagethrusters
sounds,playingwithpygamemodule/Playingsoundsusingthepygame
module
menus,buildingwithpygamemodule/Buildingmenususingthepygame
module,Objectivecomplete–minidebriefing
homeautomationproject
about/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
light,turningon/Asimpleexamplethatcontrolslimitedindoorandoutdoor
lightingintheevening,Prepareforliftoff
customarywebserverexample/Acustomarywebserverexample,Engage
thrusters,Objectivecomplete–minidebriefing
lawnsprinkler,turningon/Turningonalawnsprinkleronlywhenthereisno
rainforecast!,Engagethrusters
remoteaccess,enablingforcontrollingappliances/Gainingremoteaccessto
yourRaspberryPitocontrolappliances
considerations/Someprojectideastoconsider
Houghtransforms
about/Engagethrusters
I
I2Ccommunication
about/Whyisitawesome?,I2CCommunicationusingtheArduino(optional)
URL,fortutorials/Whyisitawesome?
7-Segmentdisplay/The7-Segmentdisplay
8x8LEDmatrix/8x8LEDmatrix
BlinkM/BlinkM
proximitysensor/Proximitysensor
ImageWriterpackage/GUI-basedapproach
Infrared(IR)emitter/detector
about/Infraredemitter/detector
infraredsensor
used,forimplementinglinefollowinglogic/Implementationoflinefollowing
logicbasedonsensordata,Engagethrusters
Instructables
URL/Whyisitawesome?
interface
URL/Sensorselection,interface,anddatainterpretation
issues,RaspberryPi
SDcardcorruption/SDcardcorruption
powerissues/Powerissues
devicespoweredbyUSB/DevicespoweredbyUSB
J
Javadevelopment
RaspberryPiused/#4JavaDevelopmentusingtheRaspberryPi
K
keyalertsystem
sensors,settingup/Settingupsensorsforthekeyalertsystem,Engage
thrusters,Objectivecomplete–minidebriefing
KhanAcademy
URL/RaspberryPiandKhanAcademy
KhanAcademyexample
about/RaspberryPiandKhanAcademy
L
lawnsprinkler
turningon/Turningonalawnsprinkleronlywhenthereisnorainforecast!,
Prepareforliftoff
LEDblinkingexample
programming/Engagethrusters
electricalconnection/Electricaloutputofourprogram,Engagethrusters
LightDependentResistors
about/LightDependentResistors
linefollowinglogic
implementing,withinfraredsensor/Implementationoflinefollowinglogic
basedonsensordata
linefollowingrobot
about/Missionbriefing
features/Whyisitawesome?
objectives/YourHotshotobjectives
checklist/Missionchecklist
prerequisites/Missionchecklist
PiPlate,assembling/AssemblyofthePiPlateforthelinefollowingrobot
PiPlate,testing/AssemblyofthePiPlateforthelinefollowingrobot
datainterpretation/Sensorselection,interface,anddatainterpretation
sensors,selecting/Engagethrusters
interface/Engagethrusters
MachineVision-based/Machine-vision-basedlinefollowingrobot
motordrivercircuit,testing/Testingthemotordrivercircuit
track,preparing/Preparationofthelinefollowingcourse
chassis,designing/Designingthechassisforthelinefollowingrobot
assembling/Astep-by-stepassemblyoftherobot
assembling,steps/Prepareforliftoff,Engagethrusters
referencelinks/References
linefollowingtrack
preparing,forrobot/Preparationofthelinefollowingcourse,Prepareforliftoff
Linux
SDcardwithRaspbianimage,flashing/Linux
LPD8806library
URL/ControllingRGBLEDsfromawebpage
M
MachineVision-basedlinefollowingrobot/Machine-vision-basedlinefollowing
robot
Make*itBasicRoboticsStarterKit
URL/Missionchecklist
marqueecontrol,ConnectFourgame
implementing/Marqueedesignandcontrol(optional),Prepareforliftoff
menuclass
URL/Addingamenuforthegame
motordrivercircuit
testing/Testingthemotordrivercircuit,Prepareforliftoff,Engagethrusters
multipleappliances
connecting,toRaspberryPi/ConnectingmultipleappliancestotheRaspberry
Pi
N
NOAA
URL/Engagethrusters
Node-REDtool
URL/#5TheThingboxproject
O
Occidentalis
about/Missionbriefing
features/Whyisitawesome?
objectives/YourHotshotobjectives
installing/Installation,features,andusageoftheOccidentalisoperatingsystem
fromAdafruit
Occidentalisdistro
requisites/Missionchecklist
OpenCV
URL/Missionchecklist
URL,forinstallationonRaspberryPi/Missionchecklist
URL,forinstallationonLinux/Missionchecklist
OpenCVDishDetectorproject
URL/Settinguptheassemblyforthedishmonitor
P
Parallax/Prepareforliftoff
personalassistant
building/Missionbriefing
objectives/Yourobjectives
checklist/Missionchecklist
e-mailfeedparser,settingup/Settingupthee-mailfeedparser,Engage
thrusters
e-mailfeedparser,settingupforreminders/Settinguptheparserforreminders
andevents,Engagethrusters
e-mailfeedparser,settingupforevents/Settinguptheparserforremindersand
events,Engagethrusters
enclosure,designing/Designinganenclosuredesignforthepersonalassistant,
Prepareforliftoff,Engagethrusters
dishmonitor,assembling/Settinguptheassemblyforthedishmonitor,Engage
thrusters,Objectivecomplete–minidebriefing
sensors,settingupforkeyalertsystem/Settingupsensorsforthekeyalert
system,Engagethrusters,Objectivecomplete–minidebriefing
implementation/Missionaccomplished
challenges/Hotshotchallenges
personalhealthmonitor
about/Missionbriefing
features/Whyisitawesome?
objectives/YourHotshotobjectives
checklist/Missionchecklist
webserver,settingupforrecordinghealthparameters/Settingupawebserver
torecordhealthparameters,Prepareforliftoff
simpleexercisetool,building/AsimpleexercisetoolusingtheRaspberryPi,
Engagethrusters
miniprojectidea/Aminiprojectidea
e-mailfeedparser,settingup/Settingupane-mailfeedparsertorefilla
prescriptionaswellasremindtheuseraboutanupcomingdoctor’sappointment,
Engagethrusters
pillremindertool,building/Asimpletoolthatremindsapersontotakehis/her
pills
pet/wildlifemonitor
about/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
python-twistedframework,installing/Engagethrusters
python-twistedframework,testing/Engagethrusters
python-twistedframework,using/Objectivecomplete–minidebriefing
SparkCore,settingup/SettingupandtestingSparkCoretointeractwith
appliances
GoogleCoder,installing/InstallingandtestingtheGoogleCoderprojectonthe
RaspberryPi
birdfeeder,settingup/Abriefoverviewofabirdfeederthattriggersacamera
considerations/Alternativesandprojectideastoconsider
PiCrust
about/IntroductiontothePiCrust–aprototypingplatformfortheRaspberryPi
PiFace
using/InterfacinggameinputsusingthePiFacemodule
installationguide,URL/Prepareforliftoff
PiFaceinterfaceboard
URL/InterfacinggameinputsusingthePiFacemodule
PiLiteLEDMatrixdisplay
URL/Marqueedesignandcontrol(optional),Prepareforliftoff
pillreminder
building/Prepareforliftoff
URL/Prepareforliftoff
PiPlate
testing/AssemblyofthePiPlateforthelinefollowingrobot,Prepareforlift
off,Objectivecomplete–minidebriefing
assembling/AssemblyofthePiPlateforthelinefollowingrobot,Engage
thrusters,Objectivecomplete–minidebriefing
PIRsensor
URL/Prepareforliftoff
Pololu
about/Prepareforliftoff
URL/Useelectricaltapeandbuildatrack
powerDarlingtoncircuit
URL/Engagethrusters
PowerSwitchTail2
using/Prepareforliftoff
softwareprerequisites/Softwareprerequisites
settingup/Engagethrusters
PowerSwitchTailII/InterfacethedevicestotheRaspberryPi
projectsideas
implementing,overweekend/Projectideasthatcanbeimplementedovera
weekend
Proportional-Integral-Derivativecontrol(PID)/Hotshotchallenge
pulse-widthmodulation
about/Whyisitawesome?
URL,fortutorials/Whyisitawesome?
PuTTYSSHclient
URL/#1–SimpletrickforPythondevelopmentviaremotelogin
python-twistedframework
about/Installingandtestingthepython-twistedframework
installing/Engagethrusters
testing/Engagethrusters
using/Objectivecomplete–minidebriefing
python-twistedframework
URL/Installingandtestingthepython-twistedframework
Pythondevelopment
viaremotelogin/#1–SimpletrickforPythondevelopmentviaremotelogin
Pythondevelopment,onWebIDE
about/PythondevelopmentontheWebIDE,Prepareforliftoff
I2Cinterface/QuickintroductiontotheI2Cinterface
I2Cinterface,configuringonRaspberryPi/ConfiguringtheI2Cinterfaceon
theRaspberryPi
I2Cinterface,configuringoonRaspberryPi/ConfiguringtheI2Cinterfaceon
theRaspberryPi,Engagethrusters
PythonIDLE3
LEDblinkingexample,programming/Engagethrusters
Q
quick2wirepythonAPI/InstallingGPIOlibraries
R
RaspberryPi
about/AquickintroductiontotheRaspberryPi,SettingupRaspberryPiasa
developmentplatform
URL/FeaturesofaRaspberryPi
features/FeaturesofaRaspberryPi
components/FeaturesofaRaspberryPi
distributors/WherecanIbuyaRaspberryPi?
requisites/RequirementstogetstartedwiththeRaspberryPi
display/RequirementstogetstartedwiththeRaspberryPi
powersupply/RequirementstogetstartedwiththeRaspberryPi
operatingsystems/OperatingsystemsontheRaspberryPi
settingup/SettinguptheRaspberryPi
GPIO/Missionbriefing
remotelogin,settingup/SetupofaremoteloginintotheRaspberryPi,Prepare
forliftoff,Engagethrusters
tipsandtricksproject/Missionbriefing
settingup,asdevelopmentplatform/SettingupRaspberryPiasadevelopment
platform
remotelogin,enabling/RemotelyloggingintheRaspberryPifromanywhere
ontheInternet
issues/ProblemsthatmightbeencounteredwhileusingRaspberryPi
add-onhardwaresources/Cooladd-onhardwaresourcesdevelopedforthe
RaspberryPiplatform
modelB,versusB+/TheRaspberryPimodelBversusB+,modelAversusA+
modelA,versusA+/TheRaspberryPimodelBversusB+,modelAversusA+
usefulresources/UsefulresourcesfortheRaspberryPi
RaspberryPiAlaMode
about/Missionbriefing,RaspberryPiAlaMode
features/Prepareforliftoff
RaspberryPieLinuxwiki
URL/RequirementstogetstartedwiththeRaspberryPi
RaspberryPiFoundationforums
URL/RaspberryPiFoundation’sforums:
about/RaspberryPiFoundation’sforums:
RaspberryPiStackExchange
about/RaspberryPiStackExchange:
URL/RaspberryPiStackExchange:
RaspberryPiWebIDE
installing/InstallationoftheRaspberryPiWebIDE,Engagethrusters
URL/InstallationoftheRaspberryPiWebIDE
Pythondevelopment/PythondevelopmentontheWebIDE,Prepareforliftoff
examples,testing/TestanddebuggingexamplesusingtheWebIDE,Preparefor
liftoff,Engagethrusters
examples,debugging/TestanddebuggingexamplesusingtheWebIDE,Prepare
forliftoff,Engagethrusters
Raspbian
about/GettingstartedwithRaspbian
downloading/DownloadingRaspbian
URL/DownloadingRaspbian
image,flashingonSDcard/FlashingimageontotheSDcard
Raspbianimage
flashing,onSDcard/FlashingimageontotheSDcard
Raspbianwheezy/DownloadingRaspbian
raspi-configtool
info/SettinguptheRaspberryPi
expand_rootfs/SettinguptheRaspberryPi
overscan/SettinguptheRaspberryPi
configure_keyboard/SettinguptheRaspberryPi
change_pass/SettinguptheRaspberryPi
change_locale/SettinguptheRaspberryPi
change_timezone/SettinguptheRaspberryPi
memory_split/SettinguptheRaspberryPi
overclock/SettinguptheRaspberryPi
ssh/SettinguptheRaspberryPi
boot_behaviour/SettinguptheRaspberryPi
update/SettinguptheRaspberryPi
remotelogin
settingup,inRaspberryPi/SetupofaremoteloginintotheRaspberryPi,
Engagethrusters
enabling/RemotelyloggingintheRaspberryPifromanywhereontheInternet
resources,RaspberryPi
about/UsefulresourcesfortheRaspberryPi
foundationforums/RaspberryPiFoundation’sforums:
StackExchange/RaspberryPiStackExchange:
Element14/Element14’sRaspberryPicommunity:
RGBLEDs
controlling,fromwebpage/ControllingRGBLEDsfromawebpage,Engage
thrusters
RGBLEDstrip
controlling,withArduino/ControllingtheRGBLEDStripusingtheArduino,
Prepareforliftoff,Objectivecomplete–minidebriefing
lightingup/LightinguptheRGBLEDstrip,AnArduino-basedcontrol
S
7-segmentbackpack/Engagethrusters
scienceandeducationproject
about/Missionbriefing
features/Whyisitawesome?
objectives/YourHotshotobjectives
vocabulary,improving/ImprovingyourvocabularyusingtheRaspberryPi,
Engagethrusters
KhanAcademyexample/RaspberryPiandKhanAcademy
sciencefairexhibit,building/Buildingasciencefairexhibitusingthe
RaspberryPi,Engagethrusters,Objectivecomplete–minidebriefing
educationalexperiments/Somesimpleeducationalexperimentsusingthe
RaspberryPi
sciencefairexhibit
building/BuildingasciencefairexhibitusingtheRaspberryPi,Engage
thrusters
Scribblerlinefollowingrobot
URL/Engagethrusters
SDcard,withRaspbianimage
flashing,onWindows/Windows
flashing,onLinux/Linux
SDcardwithRaspbianimage,flashingonLinux
command-lineinterface-basedapproach/Acommand-lineinterface-based
approach
GUI-basedapproach/GUI-basedapproach
sensors
selecting/Engagethrusters,Sensorselection
LightDependentResistors/LightDependentResistors
Infrared(IR)emitter/detector/Infraredemitter/detector
seriallibrary/Prepareforliftoff
serialportcommunication
about/SerialportcommunicationwiththeRaspberryPi
Pythonprogram,forWeasleyclock/PythonprogramfortheWeasleyclock
Arduinoacknowledgement,forcontrollingsignal/Controlflowfortheweather
clock
shebang/Engagethrusters
shields/Whyisitawesome?
simpleexercisetool
building/Prepareforliftoff,Engagethrusters
sourcefiles
URL,forOpenCVinstallation/Missionchecklist
SparkCore
URL/SettingupandtestingSparkCoretointeractwithappliances
settingup/Prepareforliftoff
LEDexample,implementing/EngageThrusters
SparkCoreboard
URL/Missionchecklist
SparkFun
URL/Alternativesolutionsandsomeprojectideastoconsider,Prepareforlift
off
SPI(SerialPeripheralInterface)/Howdoesitwork?
SSH(SecureShell)/GainingremoteaccesstoyourRaspberryPitocontrol
appliances
steppermotor
about/Prepareforliftoff
controlling,Arduinoused/Prepareforliftoff,Engagethrusters
counterclockwiserotation/Counterclockwiserotationofthesteppermotor
switches,ConnectFourdesktop
settingup,withcardboardbox/Setupoftheswitchesusingacardboardbox,
Prepareforliftoff,Engagethrusters
T
tabletopmusicalfountainproject
building/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
assembling/Missionchecklist
DIYfountainkit/Prepareforliftoff
Flaskframework,installing/InstallationoftheFlaskframework,Engage
thrusters
RGBLEDs,controllingfromwebpage/ControllingRGBLEDsfromaweb
page,Engagethrusters
e-mailalerts,settingup/Setupofthee-mailalertsinthefountain,Engage
thrusters,Objectivecomplete–minidebriefing
TheThingBoxProject
about/#5TheThingboxproject
URL/#5TheThingboxproject
tipsandtricksproject
about/Missionbriefing
features/Whyisitawesome?
objectives/Yourobjectives
checklist/Missionchecklist
Tkinter
URL/Engagethrusters
track
building,withelectricaltape/Useelectricaltapeandbuildatrack
U
UI,ConnectFourgame
about/GettingstartedwiththeConnectFourgame(UIandsoundeffects),
Prepareforliftoff
menu,adding/Addingamenuforthegame
sounds,adding/Addingsoundstothegame
USBBatterypack
URL/Prepareforliftoff
W
WeasleyWeatherClock
about/TheWeasleyweatherclock
requisites/Prepareforliftoff
assembling/Engagethrusters
Weaved
URL/GainingremoteaccesstoyourRaspberryPitocontrolappliances,
RemotelyloggingintheRaspberryPifromanywhereontheInternet
web.pytutorials
URL/References
webdevelopment
GoogleCoderused/#2WebdevelopmentusingGoogleCoder
webserver
installing/Installingthewebserver,Engagethrusters
interfacing/Interfacingthewebserver,Engagethrusters,Objectivecomplete–
minidebriefing
settingup,forrecordinghealthparameters/Settingupawebservertorecord
healthparameters,Prepareforliftoff,Engagethrusters
Win32DiskImagertool/Windows
Windows
SDcardwithRaspbianimage,flashing/Windows
WinSCP
URL/#1–SimpletrickforPythondevelopmentviaremotelogin
WonderHowTo
URL/Engagethrusters
WordnikAPI
URL/ImprovingyourvocabularyusingtheRaspberryPi
installing/Prepareforliftoff
using/Engagethrusters
WordOfTheDayobject
URL/Engagethrusters

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