Ultimate Guide For Arduino Sensors And Modules
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About the Authors
Hi there! Thank you for reading the “Ultimate Guide for Arduino Sensors and
Modules”.
“I’m Rui Santos, I have a master’s degree in Electrical and Computer Engineering. I have
more than four years of experience teaching electronics and programming with the
Random Nerd Tutorials blog. I’m also founder of RNTLab.com and author of BeagleBone
For Dummies and 20 Easy Raspberry Pi Projects book. My projects and tutorials are
related with Arduino, Home Automation, ESP8266, ESP32, and Raspberry Pi.”
“I’m Sara Santos, I have a master’s degree in Bioengineering and I’ve been working with
Rui at Random Nerd Tutorials since 2015 as a content editor. I’m the co-author of the
20 Easy Raspberry Pi Projects book and I also write and build courses with Rui.”
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Table of Contents
DHT11/DHT22 Temperature and Humidity Sensor ..................................................................... 7
BMP180 Barometric Sensor .......................................................................................................... 13
FC-37 or YL-83 Rain Sensor ........................................................................................................... 21
YL-69 or HL-69 Soil Moisture Sensor ............................................................................................ 26
DS18B20 Temperature Sensor ..................................................................................................... 31
DS1307 or DS3231 Real Time Clock (RTC) ................................................................................... 37
MQ-2 Gas/Smoke Sensor ............................................................................................................... 43
HC-SR04 Ultrasonic Sensor ........................................................................................................... 49
PIR Motion Sensor .......................................................................................................................... 53
Tilt Sensor ........................................................................................................................................ 57
Microphone Sound Sensor ............................................................................................................ 62
Reed Switch ..................................................................................................................................... 66
MRFC522 RFID ................................................................................................................................. 70
Relay Module .................................................................................................................................. 77
nRF24L01 ......................................................................................................................................... 83
433 MHz Transmitter/Receiver ..................................................................................................... 91
8x8 Dot Matrix ..............................................................................................................................102
WS2812B Addressable RGB LED Strip ........................................................................................108
Membrane Keypad .......................................................................................................................114
1.8 TFT Display ..............................................................................................................................118
SIM900 GSM GPRS Shield ............................................................................................................127
SD Card Module ............................................................................................................................146
TCS3200 color sensor...................................................................................................................152
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DHT11/DHT22 Temperature
and Humidity Sensor
These DHTXX sensors are very popular among the Arduino Tinkerers. The DHT
sensors are inexpensive sensors for measuring temperature and humidity.
These sensors contain a chip that does analog to digital conversion and spits out a
digital signal with the temperature and humidity.
These signals are easy to read with any microcontroller (MCU).
Specifications DHT11 vs DHT22
There are two versions of the DHT sensor:
DHT11
Range: 20-90%
Absolute accuracy: ±5%
Repeatability: ±1%
Long term stability: ±1% per year
Price: $1 to $5
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DHT22
Range: 0-100%
Absolute accuracy: ±2%
Repeatability: ±1%
Long term stability: ±0.5% per year
Price: $4 to $10
As you can see from the specs above, the DHT22 is a bit more accurate.
Where to buy?
Click the links below to compare the sensor at different stores and find the best price:
Click here to see DHT11 on Maker Advisor
Click here to see DHT22 on Maker Advisor
Arduino with DHT11 Sensor
For this example you need the following components:
Figure
Name
Arduino UNO
1x DHT11
Breadboard
10KΩ Resistor (or 4.7KΩ)
Jumper Wires
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Schematic
Here’s how to connect the DHT11 to an Arduino:
Pin
Wiring to Arduino UNO
1st pin - VCC
5V
2nd pin - Data OUT
Digital pin 2
3rd pin
Don’t connect
4th pin - GND
GND
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Source code
Below you can find the code you need for this project. But first you need to install
the DHT library.
1. Download the DHT11 library here
2. Unzip the DHT library
3. Rename the extracted folder to DHT and remove the “-“. Otherwise your
Arduino IDE won’t recognize your library
4. Install the DHT11 in your Arduino IDE: go to Sketch Include Library Add .
ZIP library and select the library you’ve just downloaded
5. Restart your Arduino IDE
6. Go to File Examples DHT sensor library DHTtester
7. Upload the code
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain
#include "DHT.h"
#define DHTPIN 2
// what digital pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11
// DHT 11
//#define DHTTYPE DHT22
// DHT 22 (AM2302), AM2321
//#define DHTTYPE DHT21
// DHT 21 (AM2301)
//
//
//
//
//
//
Connect pin 1 (on the left) of the sensor to +5V
NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
to 3.3V instead of 5V!
Connect pin 2 of the sensor to whatever your DHTPIN is
Connect pin 4 (on the right) of the sensor to GROUND
Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors. This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.
DHT dht(DHTPIN, DHTTYPE);
void setup() {
Serial.begin(9600);
Serial.println("DHTxx test!");
dht.begin();
}
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void loop() {
// Wait a few seconds between measurements.
delay(2000);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
// Read temperature as Celsius (the default)
float t = dht.readTemperature();
// Read temperature as Fahrenheit (isFahrenheit = true)
float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t) || isnan(f)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
// Compute heat index in Fahrenheit (the default)
float hif = dht.computeHeatIndex(f, h);
// Compute heat index in Celsius (isFahreheit = false)
float hic = dht.computeHeatIndex(t, h, false);
Serial.print("Humidity: ");
Serial.print(h);
Serial.print(" %\t");
Serial.print("Temperature: ");
Serial.print(t);
Serial.print(" *C ");
Serial.print(f);
Serial.print(" *F\t");
Serial.print("Heat index: ");
Serial.print(hic);
Serial.print(" *C ");
Serial.print(hif);
Serial.println(" *F");
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/DHTtester.ino
Demonstration
In this project the Arduino is measuring the temperature and humidity. Those two
measurements are being displayed on the serial monitor. Here’s what you should
see in your Arduino IDE serial monitor.
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BMP180 Barometric Sensor
The BMP180 barometric sensor (model GY-68) is the one in the following figure (front
and back view). It is a very small module with 1mm x 1.1mm (0.039in x 0.043in).
It measures the absolute pressure of the air around it. It has a measuring range from
300hPa to 1100hPa with an accuracy down to 0.02hPa. It can also measure altitude
and temperature.
The BMP180 barometric sensor communicates via I2C interface. This means that it
communicates with the Arduino using just 2 pins.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
BMP180 barometric sensor
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Schematic
Wire your sensor to the Arduino as shown in the schematic diagram below.
Wiring the sensor to the Arduino UNO is pretty straightforward:
Pin
Wiring to Arduino Uno
Vin
5V
GND
GND
SCL
A5
SDA
A4
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Code
To control the BMP180 barometric sensor, you need to install the SFE_BMP180
Library.
Installing the SFE_BMP180 Library
1. Click here to download the SFE_BMP180 library. You should have a .zip folder in
your Downloads folder
2. Unzip the .zip folder and you should get BMP180_Breakout_Arduino_Librarymaster folder
3. Rename your folder
from BMP180_Breakout_Arduino_Library-master to BMP180_Breakout_Ardui
no_Library
4. Move the BMP180_Breakout_Arduino_Library folder to your Arduino IDE
installation libraries folder
5. Finally, re-open your Arduino IDE
Uploading the code
Go to File Examples SparkfunBMP180 SFE_BMP180_example. This example is
very well commented and explained on how the sensor reads the pressure,
temperature and computes the altitude. Don’t upload the code now, you need to set
the altitude first.
/* SFE_BMP180 library example sketch
This sketch shows how to use the SFE_BMP180 library to read the
Bosch BMP180 barometric pressure sensor.
https://www.sparkfun.com/products/11824
Like most pressure sensors, the BMP180 measures absolute pressure.
This is the actual ambient pressure seen by the device, which will
vary with both altitude and weather.
Before taking a pressure reading you must take a temparture reading.
This is done with startTemperature() and getTemperature().
The result is in degrees C.
Once you have a temperature reading, you can take a pressure reading.
This is done with startPressure() and getPressure().
The result is in millibar (mb) aka hectopascals (hPa).
If you'll be monitoring weather patterns, you will probably want to
remove the effects of altitude. This will produce readings that can
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be compared to the published pressure readings from other locations.
To do this, use the sealevel() function. You will need to provide
the known altitude at which the pressure was measured.
If you want to measure altitude, you will need to know the pressure
at a baseline altitude. This can be average sealevel pressure, or
a previous pressure reading at your altitude, in which case
subsequent altitude readings will be + or - the initial baseline.
This is done with the altitude() function.
Hardware connections:
- (GND) to GND
+ (VDD) to 3.3V
(WARNING: do not connect + to 5V or the sensor will be damaged!)
You will also need to connect the I2C pins (SCL and SDA) to your
Arduino. The pins are different on different Arduinos:
Any Arduino pins labeled:
Uno, Redboard, Pro:
Mega2560, Due:
Leonardo:
SDA
A4
20
2
SCL
A5
21
3
Leave the IO (VDDIO) pin unconnected. This pin is for connecting
the BMP180 to systems with lower logic levels such as 1.8V
Have fun! -Your friends at SparkFun.
The SFE_BMP180 library uses floating-point equations developed by the
Weather Station Data Logger project: http://wmrx00.sourceforge.net/
Our example code uses the "beerware" license. You can do anything
you like with this code. No really, anything. If you find it useful,
buy me a beer someday.
V10 Mike Grusin, SparkFun Electronics 10/24/2013
V1.1.2 Updates for Arduino 1.6.4 5/2015
*/
// Your sketch must #include this library, and the Wire library.
// (Wire is a standard library included with Arduino.):
#include
#include
// You will need to create an SFE_BMP180 object, here called "pressure":
SFE_BMP180 pressure;
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#define ALTITUDE 1655.0 // Altitude of SparkFun's HQ in Boulder, CO. in meters
void setup()
{
Serial.begin(9600);
Serial.println("REBOOT");
// Initialize the sensor (it is important to get calibration values stored on the
device).
if (pressure.begin())
Serial.println("BMP180 init success");
else
{
// Oops, something went wrong, this is usually a connection problem,
// see the comments at the top of this sketch for the proper connections.
Serial.println("BMP180 init fail\n\n");
while(1); // Pause forever.
}
}
void loop()
{
char status;
double T,P,p0,a;
// Loop here getting pressure readings every 10 seconds.
// If you want sea-level-compensated pressure, as used in weather reports,
// you will need to know the altitude at which your measurements are taken.
// We're using a constant called ALTITUDE in this sketch:
Serial.println();
Serial.print("provided altitude: ");
Serial.print(ALTITUDE,0);
Serial.print(" meters, ");
Serial.print(ALTITUDE*3.28084,0);
Serial.println(" feet");
// If you want to measure altitude, and not pressure, you will instead need
// to provide a known baseline pressure. This is shown at the end of the sketch.
// You must first get a temperature measurement to perform a pressure reading.
// Start a temperature measurement:
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startTemperature();
if (status != 0)
{
// Wait for the measurement to complete:
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delay(status);
// Retrieve the completed temperature measurement:
// Note that the measurement is stored in the variable T.
// Function returns 1 if successful, 0 if failure.
status = pressure.getTemperature(T);
if (status != 0)
{
// Print out the measurement:
Serial.print("temperature: ");
Serial.print(T,2);
Serial.print(" deg C, ");
Serial.print((9.0/5.0)*T+32.0,2);
Serial.println(" deg F");
// Start a pressure measurement:
// The parameter is the oversampling setting, from 0 to 3 (highest res, longest
wait).
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startPressure(3);
if (status != 0)
{
// Wait for the measurement to complete:
delay(status);
// Retrieve the completed pressure measurement:
// Note that the measurement is stored in the variable P.
// Note also that the function requires the previous temperature measurement
(T).
// (If temperature is stable, you can do one temperature
number of pressure measurements.)
// Function returns 1 if successful, 0 if failure.
status = pressure.getPressure(P,T);
if (status != 0)
{
// Print out the measurement:
Serial.print("absolute pressure: ");
Serial.print(P,2);
Serial.print(" mb, ");
Serial.print(P*0.0295333727,2);
Serial.println(" inHg");
// The pressure sensor returns abolute pressure, which
// To remove the effects of altitude, use the sealevel
current altitude.
// This number is commonly used in weather reports.
// Parameters: P = absolute pressure in mb, ALTITUDE =
m.
measurement for a
varies with altitude.
function and your
current altitude in
// Result: p0 = sea-level compensated pressure in mb
p0 = pressure.sealevel(P,ALTITUDE); // we're at 1655 meters (Boulder, CO)
Serial.print("relative (sea-level) pressure: ");
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Serial.print(p0,2);
Serial.print(" mb, ");
Serial.print(p0*0.0295333727,2);
Serial.println(" inHg");
// On the other hand, if you want to determine your altitude from the
pressure reading,
// use the altitude function along with a baseline pressure (sea-level or
other).
// Parameters: P = absolute pressure in mb, p0 = baseline pressure in mb.
// Result: a = altitude in m.
a = pressure.altitude(P,p0);
Serial.print("computed altitude: ");
Serial.print(a,0);
Serial.print(" meters, ");
Serial.print(a*3.28084,0);
Serial.println(" feet");
}
else Serial.println("error retrieving pressure measurement\n");
}
else Serial.println("error starting pressure measurement\n");
}
else Serial.println("error retrieving temperature measurement\n");
}
else Serial.println("error starting temperature measurement\n");
delay(5000); // Pause for 5 seconds.
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/SFE_BMP180_example.ino
Set the altitude
Before uploading the code, you need to set up your current altitude. Go
to elevationmap.net, insert your address and check your altitude’s location. Set your
altitude in the code. The place where you should write your altitude is commented.
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Demonstration
After uploading the code, open your serial monitor at a baud rate of 9600. You’ll see
your sensor readings.
Wrapping up
The BMP180 is an interesting sensor to be used in your own weather station. Because
the pressure changes with the altitude, this sensor can also compute the altitude.
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FC-37 or YL-83 Rain Sensor
The rain sensor is used to detect water and it can detect beyond what a humidity
sensor can. The FC-37 rain sensor (or other versions like YL-83) is set up by two
pieces: the electronic board (at the left) and the collector board (at the right) that
collects the water drops, as you can see in the following figure:
The rain sensor has a built-in potentiometer for sensitivity adjustment of the digital
output (D0). It also has a power LED that lights up when the sensor is turned on and
a digital output LED.
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How does it work?
In simple terms, the resistance of the collector board varies accordingly to the
amount of water on its surface.
When the board is:
Wet: the resistance increases, and the output voltage decreases
Dry: the resistance is lower, and the output voltage is higher
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
YL-83 rain sensor
Example: Rain Sensor with Arduino
This is a simple example to show you how you can use the rain sensor in your projects
with Arduino. You will read the analog sensor values and print them in the Arduino
IDE serial monitor.
For this example, you’ll need the following parts:
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Figure
Name
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Arduino UNO
Maker Advisor
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YL-83 Rain Sensor
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Breadboard
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2× 220Ω resistor
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2× LEDs
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Jumper Wires
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Pin Wiring
Sensor Pin
Wiring to Arduino Uno
A0
Any analog pin (A5 in this example)
D0
Digital pins
GND
GND
VCC
5V
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Schematic
Follow the next schematic diagram to complete the project:
Code
Upload the following sketch to your Arduino board (feel free to adjust the
variable thresholdValue with a different threshold value):
/*
All the resources for this project:
http://randomnerdtutorials.com/
*/
int rainPin = A0;
int greenLED = 6;
int redLED = 7;
// you can adjust the threshold value
int thresholdValue = 500;
void setup(){
pinMode(rainPin, INPUT);
pinMode(greenLED, OUTPUT);
pinMode(redLED, OUTPUT);
digitalWrite(greenLED, LOW);
digitalWrite(redLED, LOW);
Serial.begin(9600);
}
void loop() {
// read the input on analog pin 0:
int sensorValue = analogRead(rainPin);
Serial.print(sensorValue);
if(sensorValue < thresholdValue){
Serial.println(" - It's wet");
digitalWrite(greenLED, LOW);
digitalWrite(redLED, HIGH);
}
else {
Serial.println(" - It's dry");
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digitalWrite(greenLED, HIGH);
digitalWrite(redLED, LOW);
}
delay(500);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/rain_sensor_arduino.ino
Open the Arduino IDE serial monitor to see the results. Then, add drops of water to
the collector board and see how that changes the readings. When the value goes
below a certain threshold, a red LED will light up, and when the value goes above a
certain threshold, a green LED will light up.
Wrapping up
If you want to know when it’s raining, you need to set up your rain sensor with the
Arduino outside. Be aware that you should protect your Arduino and your circuit
from water. A waterproof project box can be handy in this situation.
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YL-69 or HL-69 Soil Moisture Sensor
The soil moisture sensor or the hygrometer is usually used to detect the humidity of
the soil. So, it is perfect to build an automatic watering system or to monitor the soil
moisture of your plants.
The sensor is set up by two pieces: the electronic board (at the right), and the probe
with two pads, that detects the water content (at the left).
The sensor has a built-in potentiometer for sensitivity adjustment of the digital
output (D0), a power LED and a digital output LED, as you can see in the following
figure.
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How does it work?
The voltage that the sensor outputs changes accordingly to the water content in the
soil. When the soil is:
Wet: the output voltage decreases
Dry: the output voltage increases
The output can be a digital signal (D0) LOW or HIGH, depending on the water
content. If the soil humidity exceeds a certain predefined threshold value, the
modules outputs LOW, otherwise it outputs HIGH. The threshold value for the
digital signal can be adjusted using the potentiometer. The output can also be an
analog signal and so you’ll get a value between 0 and 1023.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
HL-69 soil moisture sensor
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Soil Moisture Sensor with the Arduino
In this example, you’ll read the analog sensor output values using the Arduino and
print those readings in the Arduino IDE serial monitor.
For this example, you’ll need the following components:
Figure
Name
Check Price
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Arduino UNO
Maker Advisor
Find best price on
HL-69 Rain Sensor
Maker Advisor
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Breadboard
Maker Advisor
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2× 220Ω Resistor
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2× LEDs
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Jumper Wires
Maker Advisor
Pin Wiring
Sensor Pin
Wiring to Arduino Uno
A0
Any analog pin (A5 in this example)
D0
Digital pins
GND
GND
VCC
5V
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Schematic
To complete the project, follow the next schematic diagram:
Code
Upload the following sketch to your Arduino board:
/* All the resources for this project:
http://randomnerdtutorials.com/
*/
int rainPin = A0;
int greenLED = 6;
int redLED = 7;
// you can adjust the threshold value
int thresholdValue = 800;
void setup(){
pinMode(rainPin, INPUT);
pinMode(greenLED, OUTPUT);
pinMode(redLED, OUTPUT);
digitalWrite(greenLED, LOW);
digitalWrite(redLED, LOW);
Serial.begin(9600);
}
void loop() {
// read the input on analog pin 0:
int sensorValue = analogRead(rainPin);
Serial.print(sensorValue);
if(sensorValue < thresholdValue){
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Serial.println(" - Doesn't need watering");
digitalWrite(redLED, LOW);
digitalWrite(greenLED, HIGH);
}
else {
Serial.println(" - Time to water your plant");
digitalWrite(redLED, HIGH);
digitalWrite(greenLED, LOW);
}
delay(500);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/soil_moisture_sensor_arduino.ino
Open the Arduino IDE serial monitor to see the values. Then, try your sensor in a wet
and in a dry soil and see what happens.
When the analog value goes above a certain threshold, a red LED will turn on
(indicates that the plant needs watering), and when the value goes below a certain
threshold, a green LED will turn on (indicates that the plant is ok).
Wrapping up
The moisture sensor allows to monitor the water content in the soil. This is useful if
you want to build an automatic watering system. You can also use it to just monitor
your plants soil moisture.
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DS18B20 Temperature Sensor
The DS18B20 temperature sensor is a 1-wire digital temperature sensor. This means
that you can read the temperature with a very simple circuit setup. It communicates
on common bus, which means that you can connect several devices and read their
values using just one digital pin of the Arduino.
The sensor has just three pins as you can see in the following figure:
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The DS18B20 is also available in waterproof version:
Features
Here’s some main features of the DS18B20 temperature sensor:
Communicates over 1-wire bus communication
Operating range temperature: -55ºC to 125ºC
Accuracy +/-0.5 ºC (between the range -10ºC to 85ºC)
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
DS18B20 digital temperature sensor
DS18B20 temperature sensor with the Arduino
In this example, you’ll read the temperature using the DS18B20 sensor and the
Arduino. The readings will be displayed on the Arduino Serial Monitor.
For this example, you’ll need the following parts:
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Figure
Name
Arduino UNO
DS18B20 temperature sensor
Breadboard
4.7kΩ Resistor
Jumper Wires
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Schematic
The sensor can operate in two different modes:
Normal mode: 3-wire connection is needed. Here’s the schematic you need to
follow:
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Parasite mode: only 2 wires required, the data and ground. The sensor derives
its power from the data line. In this case, here’s the schematic you need to
follow:
You can read the temperature of more than one sensor at the same time using just
one digital Arduino pin. For that, you just need to connect all the DQ pins to any
digital Arduino pin.
Code
You’ll need to install the OneWire Library and DallasTemperature Library.
Installing the OneWire Library
1. Click here to download the OneWire library. You should have a .zip folder
in your Downloads
2. Unzip the .zip folder and you should get OneWire-master folder
3. Rename your folder from OneWire-master to OneWire
4. Move the OneWire folder to your Arduino IDE installation libraries folder
5. Finally, re-open your Arduino IDE
Installing the DallasTemperature Library
1. Click here to download the DallasTemperature library. You should have a .zip
folder in your Downloads
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2. Unzip the .zip folder and you should get Arduino-Temperature-ControlLibrary-master folder
3. Rename
your
folder
from Arduino-Temperature-Control-Library-
master to DallasTemperature
4. Move
the DallasTemperature folder
to
your
Arduino
IDE
installation libraries folder
5. Finally, re-open your Arduino IDE
After installing the needed libraries, upload the following code to your Arduino
board.
/*
Rui Santos
Complete project details at http://randomnerdtutorials.com
Based on the Dallas Temperature Library example
*/
#include
#include
// Data wire is connected to the Arduino digital pin 2
#define ONE_WIRE_BUS 2
// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);
// Pass our oneWire reference to Dallas Temperature sensor
DallasTemperature sensors(&oneWire);
void setup(void)
{
// Start serial communication for debugging purposes
Serial.begin(9600);
// Start up the library
sensors.begin();
}
void loop(void){
// Call sensors.requestTemperatures() to issue a global temperature and Requests to
all devices on the bus
sensors.requestTemperatures();
Serial.print("Celsius temperature: ");
// Why "byIndex"? You can have more than one IC on the same bus. 0 refers to the
first IC on the wire
Serial.print(sensors.getTempCByIndex(0));
Serial.print(" - Fahrenheit temperature: ");
Serial.println(sensors.getTempFByIndex(0));
delay(1000);
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/DS18B20_Temperature_Sensor_Arduino.ino
Finally, you should open the Arduino IDE serial monitor at a 9600 baud rate and you’ll
see the temperature displayed in both Celsius and Fahrenheit:
Wrapping up
The DS18B20 temperature sensor is a very useful one. It allows you to read the
temperature both in Celsius and Fahrenheit via One Wire communication. This
means you can have readings from several sensors without multiplying the
connections to the Arduino.
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DS1307 or DS3231 Real Time Clock (RTC)
The real time clock module is the one in the figure below (front and back view).
When you first use this module, you need to solder some header pins.
As you can see in the picture above, the module has a backup battery installed. This
allows the module to retain the time, even when it’s not being powered up by the
Arduino. This way, every time you turn on and off your module, the time doesn’t reset.
This module uses I2C communication. This means that it communicates with the
Arduino using just 2 pins.
Where to buy?
Click the link below to compare the module at different stores and find the best price:
DS1307 Real Time Clock Module
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Pin wiring
Module Pin
Wiring to Arduino Uno
SCL
A5
SDA
A4
VCC
5V
GND
GND
If you’re using other Arduino board rather than the Uno, check out what are their SCL
and SDA pins.
Nano: SDA (A4); SCL(A5)
MEGA: SDA (20); SCL(21)
Leonardo: SDA (20); SCL(21)
Displaying date and time in the serial monitor
In this example you’ll display the data and time in the serial monitor.
Schematics
Connect your Real Time Clock module to your Arduino as in the schematics below.
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Code
Working with the RTC requires two important steps:
setting the current time, so that the RTC knows what time is it
retaining the time, so that the RTC always gives the correct time, even
when it is turned off
Set the current time in the Real Time Clock
For setting the current time you need to change the code provided. Set your current
time in the function setDS3231time()
The parameters for the function are highlighted in red: seconds, minutes, hours, day
of the week, date, month and year (in this order). Sunday is the day 1 of the week
and Saturday is 7. Don’t forget to uncomment that line of code.
After setting the current time, you can upload the provided code with the required
modifications.
The code provided was written by John Boxall from tronixstuff. You can read his
tutorial here.
// Written by John Boxall from http://tronixstuff.com
#include "Wire.h"
#define DS3231_I2C_ADDRESS 0x68
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val){
return( (val/10*16) + (val%10) );
}
// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val){
return( (val/16*10) + (val%16) );
}
void setup(){
Wire.begin();
Serial.begin(9600);
// set the initial time here:
// DS3231 seconds, minutes, hours, day, date, month, year
setDS3231time(30,42,16,5,13,10,16);
}
void setDS3231time(byte second, byte minute, byte hour, byte dayOfWeek, byte
dayOfMonth, byte month, byte year){
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// sets time and date data to DS3231
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0); // set next input to start at the seconds register
Wire.write(decToBcd(second)); // set seconds
Wire.write(decToBcd(minute)); // set minutes
Wire.write(decToBcd(hour)); // set hours
Wire.write(decToBcd(dayOfWeek)); // set day of week (1=Sunday, 7=Saturday)
Wire.write(decToBcd(dayOfMonth)); // set date (1 to 31)
Wire.write(decToBcd(month)); // set month
Wire.write(decToBcd(year)); // set year (0 to 99)
Wire.endTransmission();
}
void readDS3231time(byte *second,
byte *minute,
byte *hour,
byte *dayOfWeek,
byte *dayOfMonth,
byte *month,
byte *year){
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0); // set DS3231 register pointer to 00h
Wire.endTransmission();
Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
// request seven bytes of data from DS3231 starting from register 00h
*second = bcdToDec(Wire.read() & 0x7f);
*minute = bcdToDec(Wire.read());
*hour = bcdToDec(Wire.read() & 0x3f);
*dayOfWeek = bcdToDec(Wire.read());
*dayOfMonth = bcdToDec(Wire.read());
*month = bcdToDec(Wire.read());
*year = bcdToDec(Wire.read());
}
void displayTime(){
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
// retrieve data from DS3231
readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month,
&year);
// send it to the serial monitor
Serial.print(hour, DEC);
// convert the byte variable to a decimal number when displayed
Serial.print(":");
if (minute<10){
Serial.print("0");
}
Serial.print(minute, DEC);
Serial.print(":");
if (second<10){
Serial.print("0");
}
Serial.print(second, DEC);
Serial.print(" ");
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Serial.print(dayOfMonth, DEC);
Serial.print("/");
Serial.print(month, DEC);
Serial.print("/");
Serial.print(year, DEC);
Serial.print(" Day of week: ");
switch(dayOfWeek){
case 1:
Serial.println("Sunday");
break;
case 2:
Serial.println("Monday");
break;
case 3:
Serial.println("Tuesday");
break;
case 4:
Serial.println("Wednesday");
break;
case 5:
Serial.println("Thursday");
break;
case 6:
Serial.println("Friday");
break;
case 7:
Serial.println("Saturday");
break;
}
}
void loop(){
displayTime(); // display the real-time clock data on the Serial Monitor,
delay(1000); // every second
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/rtc_example.ino
Retain the time in the Real Time Clock
If you don’t want to reset the time every time the RTC is turned off, you should do
the following: after setting up the time, you should comment the function that sets
the time and upload the code again.
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This is a very important step to set up the time in your RTC. If you don’t do this, every
time your RTC resets, it will display the time that you’ve set up previously instead of
the current time.
Demonstration
Open the serial monitor at a baud rate of 9600 and you’ll see the results. Here’s the
Serial Monitor displaying the current date and time.
Wrapping up
The RTC module is useful and you can use it as a clock, timer, etc. A very interesting
project to do with the RTC is an alarm clock with and OLED display, for example.
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MQ-2 Gas/Smoke Sensor
This guide shows how to build a smoke detector that beeps when it detects
flammable gas or smoke. The MQ-2 smoke sensor is shown in the following figure:
The MQ-2 smoke sensor is sensitive to smoke and to the following flammable gases:
LPG, butane, propane, methane, alcohol and hydrogen. The resistance across the
sensor is different depending on the type of the gas. The smoke sensor has a builtin potentiometer that allows you to adjust the sensor digital output (D0) threshold.
This threshold sets the value above which the digital pin will output a HIGH signal.
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How does it work?
The voltage that the sensor outputs changes accordingly to the smoke/gas level that
exists in the atmosphere. The sensor outputs a voltage that is proportional to the
concentration of smoke/gas.
In other words, the relationship between voltage and gas concentration is the
following:
The greater the gas concentration, the greater the output voltage
The lower the gas concentration, the lower the output voltage
The output can be an analog signal (A0) that can be read with an analog input of the
Arduino or a digital output (D0) that can be read with a digital input of the Arduino.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
MQ-2 Gas and Smoke Sensor
Gas Sensor with Arduino
In this example, you will read the sensor analog output voltage. When the smoke
reaches a certain level, it will make sound a buzzer and a red LED will turn on.
When the output voltage is below that level, a green LED will be on.
For this example, you’ll need the following parts:
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Figure
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Pin wiring
Sensor Pin
Wiring to Arduino Uno
A0
Analog pins
D0
Digital pins
GND
GND
VCC
5V
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Schematic
Follow the next schematic diagram to complete the project:
Code
Upload the following sketch to your Arduino board (feel free to adjust the
variable sensorThres with a different threshold value):
/*******
All the resources for this project:
http://randomnerdtutorials.com/
*******/
int redLed = 12;
int greenLed = 11;
int buzzer = 10;
int smokeA0 = A5;
// Your threshold value
int sensorThres = 400;
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void setup() {
pinMode(redLed, OUTPUT);
pinMode(greenLed, OUTPUT);
pinMode(buzzer, OUTPUT);
pinMode(smokeA0, INPUT);
Serial.begin(9600);
}
void loop() {
int analogSensor = analogRead(smokeA0);
Serial.print("Pin A0: ");
Serial.println(analogSensor);
// Checks if it has reached the threshold value
if (analogSensor > sensorThres)
{
digitalWrite(redLed, HIGH);
digitalWrite(greenLed, LOW);
tone(buzzer, 1000, 200);
}
else
{
digitalWrite(redLed, LOW);
digitalWrite(greenLed, HIGH);
noTone(buzzer);
}
delay(100);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/smoke_detector.ino
Demonstration
When you press a lighter next to the sensor, the red LED lights up and the buzzer
beeps. You can also see at the serial monitor, the values changing and surpassing
the threshold value.
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Wrapping up
The MQ-2 gas sensor allows you to detect a wide variety of gases in the environment.
It is very useful to build a smoke detector at home.
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HC-SR04 Ultrasonic Sensor
The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like
bats do. It offers excellent non-contact range detection with high accuracy and stable
readings in an easy-to-use package. From 2 cm to 400 cm or 1” to 13 feet. It comes
complete with ultrasonic transmitter and receiver module.
The HC-SR04 ultrasonic sensor is shown in the following figure:
Features
Power Supply :+5V DC
Quiescent Current : <2mA
Working Current: 15mA
Effectual Angle: <15°
Ranging Distance : 2cm – 400 cm/1″ – 13ft
Resolution : 0.3 cm
Measuring Angle: 30 degree
Trigger Input Pulse width: 10uS
Dimensions: 45mm x 20mm x 15mm
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Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
HC-SR04 Ultrasonic Sensor
Arduino with HC – SR04 Sensor
In this project the ultrasonic sensor reads and writes the distance in the serial
monitor.
Note: There’s an Arduino library called NewPing that can make your life easier when
using this sensor.
Schematic
Wire your sensor by following the schematic diagram below.
Sensor Pin
Wiring to Arduino Uno
VCC
5V
Trig
Trigger (INPUT) D9
Echo
Echo (OUTPUT) D12
GND
GND
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Source code
Upload the following code to your Arduino IDE.
/*
* created by Rui Santos, http://randomnerdtutorials.com
*
* Complete Guide for Ultrasonic Sensor HC-SR04
*
Ultrasonic sensor Pins:
VCC: +5VDC
Trig : Trigger (INPUT) - Pin11
Echo: Echo (OUTPUT) - Pin 12
GND: GND
*/
int trigPin = 11;
int echoPin = 12;
long duration, cm, inches;
void setup() {
//Serial Port begin
Serial.begin (9600);
//Define inputs and outputs
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}
void loop()
{
// The sensor is triggered by a HIGH pulse of 10 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
digitalWrite(trigPin, LOW);
delayMicroseconds(5);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// Read the signal from the sensor: a HIGH pulse whose
// duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(echoPin, INPUT);
duration = pulseIn(echoPin, HIGH);
// convert the time into a distance
cm = (duration/2) / 29.1;
inches = (duration/2) / 74;
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();
delay(250);
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Ultrasonic_Sensor_HC-SR04.c
Source code with NewPing
Below there is an example using the NewPing library. Download the library here.
/*
* Posted on http://randomnerdtutorials.com
* created by http://playground.arduino.cc/Code/NewPing
*/
#include
#define TRIGGER_PIN 12
#define ECHO_PIN 11
#define MAX_DISTANCE 200
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and
maximum distance.
void setup() {
Serial.begin(9600);
}
void loop() {
delay(50);
unsigned int uS = sonar.ping_cm();
Serial.print(uS);
Serial.println(‘‘cm’’);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Ultrasonic_Sensor_HC-SR04_with_NewPing.c
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PIR Motion Sensor
The PIR motion sensor is ideal to detect movement. PIR stand for “Passive
Infrared”. Basically, the PIR motion sensor measures infrared light from objects in its
field of view. So, it can detect motion based on changes in infrared light in the
environment. It is ideal to detect if a human has moved in or out of the sensor range.
The sensor in the figure above has two built-in potentiometers to adjust the delay
time (the potentiometer at the left) and the sensitivity (the potentiometer at the right).
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
PIR Motion Sensor (HC-SR501)
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Detecting motion with the PIR motion sensor
In this example an LED will light up when movement is detected. For this example,
you need the following parts:
Figure
Name
Arduino UNO
PIR motion sensor
2 x LEDs
Jumper Wires
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Schematic
Assemble all the parts by following the schematic below.
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Pin wiring
Sensor Pin
Wiring to Arduino Uno
GND
GND
OUT
Arduino digital pin
5V
5V
Code
Upload the following code.
/*
Arduino with PIR motion sensor
For complete project details, visit: http://RandomNerdTutorials.com/pirsensor
Modified by Rui Santos based on PIR sensor by Limor Fried
*/
int
int
int
int
led = 13;
sensor = 2;
state = LOW;
val = 0;
void setup() {
pinMode(led, OUTPUT);
pinMode(sensor, INPUT);
Serial.begin(9600);
}
void loop(){
val = digitalRead(sensor);
if (val == HIGH) {
digitalWrite(led, HIGH);
delay(100);
//
//
//
//
the pin that the LED is atteched to
the pin that the sensor is atteched to
by default, no motion detected
variable to store the sensor status (value)
// initalize LED as an output
// initialize sensor as an input
// initialize serial
//
//
//
//
read sensor value
check if the sensor is HIGH
turn LED ON
delay 100 milliseconds
if (state == LOW) {
Serial.println("Motion detected!");
state = HIGH;
// update variable state to HIGH
}
}
else {
digitalWrite(led, LOW); // turn LED OFF
delay(200);
// delay 200 milliseconds
if (state == HIGH){
Serial.println("Motion stopped!");
state = LOW;
// update variable state to LOW
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}
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Arduino_with_PIR_motion_sensor.ino
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Tilt Sensor
The tilt sensor is many times referred to as inclinometer, tilt switch or rolling ball
sensor. Using a tilt sensor is a simple way to detect orientation or inclination.
The tilt sensor module is the one in the following figure.
The tilt sensor allows to detect orientation or inclination. It detects if the sensor is
completely upright or if it is tilted.
This makes it very useful to be used, for example, in toys, robots and other
appliances whose working methodology depends on inclination.
How does it work?
The tilt sensor is cylindrical and contains a free conductive rolling ball inside with two
conductive elements (poles) beneath.
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Here's how it works:
When the sensor is completely upright, the ball falls to the bottom of the
sensor and connects the poles, allowing the current to flow.
When the sensor is tilted, the ball doesn't touch the poles, the circuit is open,
and the current doesn't flow.
This way, the tilt sensor acts like a switch that is turned on or off depending on its
inclination. So, it will give digital information to the Arduino, either a HIGH or a LOW
signal.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Tilt Sensor
Pin wiring
Wiring the tilt sensor to you Arduino is straightforward. You just need to connect one
pin to the Arduino digital pins and the GND to the GND.
If you connect the sensor like so, you need to activate the Arduino internal pull-up
resistor for the digital pin to which your sensor is connected to. Otherwise, you
should use a 10kOhm pull up resistor in your circuit.
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Example: Tilt sensitive LED
This is just a simple example for you to start put hands on your tilt sensor. In this
example, an LED will be turned off if the sensor is upright and will be turned on if the
sensor is tilted.
Figure
Name
Arduino UNO
Tilt Sensor
Breadboard
2 x LEDs
220Ω Resistor
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Jumper Wires
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Schematics
For this example, you just need to add an LED to the schematics in the "Pin Wiring"
section.
Code
To complete this example, upload the following code.
/*
* Rui Santos
* Complete Project Details http://randomnerdtutorials.com
*/
int ledPin = 12;
int sensorPin = 4;
int sensorValue;
int lastTiltState = HIGH;
// the previous reading from the tilt sensor
// the following variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long lastDebounceTime = 0; // the last time the output pin was toggled
long debounceDelay = 50;
// the debounce time; increase if the output flickers
void setup(){
pinMode(sensorPin, INPUT);
digitalWrite(sensorPin, HIGH);
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pinMode(ledPin, OUTPUT);
Serial.begin(9600);
}
void loop(){
sensorValue = digitalRead(sensorPin);
// If the switch changed, due to noise or pressing:
if (sensorValue == lastTiltState) {
// reset the debouncing timer
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer
// than the debounce delay, so take it as the actual current state:
lastTiltState = sensorValue;
}
digitalWrite(ledPin, lastTiltState);
Serial.println(sensorValue);
delay(500);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Arduino_tilt_sensor.ino
Demonstration
In the end, this is what you'll have.
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Microphone Sound Sensor
This guide shows how to use the microphone sound sensor with the Arduino. The
microphone sound sensor, as the name says, detects sound. It gives a measurement
of how loud a sound is.
There is a wide variety of these sensors. The figure below you can see the most
common ones used with the Arduino.
At the left you can see the KY-038 and at the right the LM393 microphone sound
sensors. Both sensor modules have a built-in potentiometer to adjust the sensitivity
of the digital output pins.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Microphone sound sensor KY-038
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Pin wiring
Sensor Pin
Wiring to Arduino Uno
A0
Analog pins
D0
Digital pins
GND
GND
VCC
5V
If you're using the LM 393 module, you should connect the OUT pin to an Arduino
digital pin.
Example: Sound Sensitive Lights
In this example, a microphone sensor will detect the sound intensity of your
surroundings and will light up and LED if the sound intensity is above a certain
threshold.
You can modify this project by adding more LEDs. You can also adjust your sensor
sensitivity so that the LEDs are turned on or off accordingly to the beat of a music.
For this example, you’ll need the following components.
Figure
Name
Arduino UNO
Microphone sound sensor
Breadboard
LED
220Ω Resistor
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Schematic
Assemble all the parts by following the schematic below:
Code
Upload the following code to your Arduino.
/*
* Rui Santos
* Complete Project Details http://randomnerdtutorials.com
*/
int ledPin=13;
int sensorPin=7;
boolean val =0;
void setup(){
pinMode(ledPin, OUTPUT);
pinMode(sensorPin, INPUT);
Serial.begin (9600);
}
void loop (){
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val =digitalRead(sensorPin);
Serial.println (val);
// when the sensor detects a signal above the threshold value, LED flashes
if (val==HIGH) {
digitalWrite(ledPin, HIGH);
}
else {
digitalWrite(ledPin, LOW);
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Arduino_microphone_sensor.ino
Demonstration
After uploading the code, you can clap next to the sensor. If the LED is not turning
on, you need to change the sensor sensitivity by rotating the potentiometer.
You can also adjust the sensitivity so that the LED follows the beat of a certain music.
Add more LEDs to a more spectacular effect.
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Reed Switch
A magnetic contact switch is basically a reed switch encased in a plastic shell so that
you can easily apply them in a door, a window or a drawer to detect if the door is
open or closed.
The switch that we are going to use has two parts: the switch itself, that usually comes
opened and the magnet. When you buy this switch, it also comes with 4 screws, so
that you can attach it to your door.
How does it work?
It’s very simple. The electrical circuit is closed when a magnet is near the switch (less
than 13 mm (0.5’’) away). When the magnet is far away from the switch, the circuit is
open. See the figure below.
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Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Magnetic reed switch
Project example
In this example, we will turn on a red LED if your door is open and a green LED if your
door is closed.
Figure
Name
Arduino UNO
Magnetic reed switch
Breadboard
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LED
2x 220Ω Resistor, 1x 10kΩ Resistor
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Schematic
Follow the next schematic diagram to complete this project.
Code
For this example, upload the following code:
/*
Created by Rui Santos
All the resources for this project:
http://randomnerdtutorials.com/
*/
int ledOpen=8;
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int ledClose=10;
int switchReed=6;
void setup(){
pinMode(ledOpen, OUTPUT);
pinMode(ledClose, OUTPUT);
pinMode(switchReed, INPUT);
Serial.begin(9600);
}
void loop(){
if (digitalRead(switchReed)==HIGH){
digitalWrite(ledOpen, LOW);
digitalWrite(ledClose, HIGH);
Serial.println("Your Door is Closed");
}
else {
digitalWrite(ledOpen, HIGH);
digitalWrite(ledClose, LOW);
Serial.println("Your Door is Open");
}
delay(1);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Magnetic_Contact_Switch.ino
Demonstration
You can watch this video demonstration to see the project in action:
https://youtu.be/yY0DK8fe04w
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MRFC522 RFID
RFID means radio-frequency identification. RFID uses electromagnetic fields to
transfer data over short distances. RFID is useful to identify people, to make
transactions, etc.
You can use an RFID system to open a door. For example, only the person with the
right information on his card can enter. An RFID system uses:
tags attached to the object to be identified, in this example we have a keychain
and an electromagnetic card. Each tag has his own unique identification (UID).
two-way radio transmitter-receiver, the reader, that send a signal to the tag
and read its response.
Specifications
Input voltage: 3.3V
Frequency: 13.56MHz
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Where to Buy?
Click the link below to compare the module at different stores and find the best price:
MRFC522 RFID
Pin wiring
Sensor Pin
Wiring to Arduino Uno
SDA
Digital 10
SCK
Digital 13
MOSI
Digital 11
MISO
Digital 12
IRQ
Don’t connect
GND
GND
RST
Digital 9
3.3V
3.3V
Reading Data from a RFID tag
In this example you will read data from an RFID tag. You will authorize a
predetermined tag and deny the others.
Schematic
Wire your RFID reader module as in the schematic below.
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Library download
You need the RFID library for this project:
1. Click here to download the RFID library here created by miguelbalboa. You
should have a .zip folder in your Downloads folder.
2. Unzip the .zip folder and you should get rfid-master folder.
3. Rename your folder from rfid-master to rfid.
4. Move the rfid folder to your Arduino IDE installation libraries folder.
5. Finally, re-open your Arduino IDE.
6. Restart your Arduino IDE
Go to File Examples MFRC522 DumpInfo and upload the code. This code will
be available in your Arduino IDE (after installing the RFID library).
Then, open the serial monitor. You should see something like the figure below:
Approximate the RFID card or the keychain to the reader. Let the reader and the tag
closer until all the information is displayed.
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This is the information that you can read from the card, including the card UID that
is highlighted in yellow. The information is stored in the memory that is divided into
segments and blocks as you can see in the previous picture. You have 1024 bytes of
data storage divided into 16 sectors.
Write down your UID card because you’ll need it later.
Then, you need the following code (don’t upload it now).
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/*
*
* All the resources for this project: http://randomnerdtutorials.com/
* Modified by Rui Santos
*
* Created by FILIPEFLOP
*
*/
#include
#include
#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);
// Create MFRC522 instance.
void setup()
{
Serial.begin(9600);
// Initiate a serial communication
SPI.begin();
// Initiate SPI bus
mfrc522.PCD_Init();
// Initiate MFRC522
Serial.println("Approximate your card to the reader...");
Serial.println();
}
void loop()
{
// Look for new cards
if ( ! mfrc522.PICC_IsNewCardPresent())
{
return;
}
// Select one of the cards
if ( ! mfrc522.PICC_ReadCardSerial())
{
return;
}
//Show UID on serial monitor
Serial.print("UID tag :");
String content= "";
byte letter;
for (byte i = 0; i < mfrc522.uid.size; i++)
{
Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
Serial.print(mfrc522.uid.uidByte[i], HEX);
content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
content.concat(String(mfrc522.uid.uidByte[i], HEX));
}
Serial.println();
Serial.print("Message : ");
content.toUpperCase();
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if (content.substring(1) == "BD 31 15 2B") //change here the UID of the card/cards
that you want to give access
{
Serial.println("Authorized access");
Serial.println();
delay(3000);
}
else
{
Serial.println(" Access denied");
delay(3000);
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/MFRC522_RFID_Reader_with_Arduino.ino
In the piece of code above you need to change the line
if (content.substring(1) == “REPLACE WITH YOUR UID”) and type the UID
card you’ve written previously.
Demonstration
Now, upload the code to your Arduino and open the serial monitor.
Approximate the card you’ve chosen to give access and you’ll see:
If you approximate another tag with another UID, the denial message will show up:
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You can watch the following video demonstration to see the project in action:
https://youtu.be/mpLzcBDBl1U
Wrapping up
The MFRC522 RFID reader allows you to do a project in which you have security
access to something. For example, only the right tag can open a specific door. This is
just a simple guide to show you how this reader works. Now, the idea is for you to
apply this knowledge and use your imagination to make your own projects.
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Relay Module
A relay is an electrically operated switch of mains voltage. It can be turned on or off,
letting the current go through or not. The relay module is shown in the figure below.
This module has two channels (those blue cubes).
Where to buy?
Click the link below to compare the module at different stores and find the best price:
Relay module
Mains voltage connections
In relation to mains voltage, relays have 3 possible connections:
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COM: common pin
NO: normally open – there is no contact between the common pin and the
normally open pin. So, when you trigger the relay, it connects to the COM
pin and power is provided to the load (a desktop lamp, in our case).
NC: normally closed – there is contact between the common pin and the
normally closed pin. There is always connection between the COM and NC
pins, even when the relay is turned off. When you trigger the relay, the
circuit is opened and there is no supply provided to the load.
If you want to control a lamp for example, it is better to use a normally-open circuit,
because we just want to light up the lamp occasionally.
Pin wiring
The connections between the relay and the Arduino are simple:
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GND: goes to ground
IN1: controls the first relay. Should be connected to an Arduino digital pin
IN2: controls the second relay. Should be connected to an Arduino digital
pin if you are using this second relay. Otherwise, you don’t need to connect
it.
VCC: goes to 5V.
Controlling a Lamp with a Relay Module and PIR
Motion Sensor
In this example you will create a motion sensitive lamp. A lamp will light up for 10
seconds every time motion is detected. Motion will be detected using a PIR motion
sensor.
Figure
Name
Arduino UNO
Relay Module
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Lamp Cord Set
PIR Motion Sensor
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Schematic
Assemble all the parts by following the schematic diagram below.
Be very careful with the mains voltage connections. Make sure you have the relay
unplugged from mains voltage when assembling the circuit.
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Code
Copy the following code to your Arduino IDE and upload it to your Arduino board.
/*********
Rui Santos
Complete project details at http://randomnerdtutorials.com
*********/
// Relay pin is connected to D8. The active wire is connected to Normally open and
common
int relay = 8;
volatile byte relayState = LOW;
// PIR Motion Sensor is connected to D2.
int PIRInterrupt = 2;
// Timer Variables
long lastDebounceTime = 0;
long debounceDelay = 10000;
void setup() {
// Pin for relay module set as output
pinMode(relay, OUTPUT);
digitalWrite(relay, HIGH);
// PIR motion sensor set as an input
pinMode(PIRInterrupt, INPUT);
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// Triggers detectMotion function on rising mode to turn the relay on, if the
condition is met
attachInterrupt(digitalPinToInterrupt(PIRInterrupt), detectMotion, RISING);
// Serial communication for debugging purposes
Serial.begin(9600);
}
void loop() {
// If 10 seconds have passed, the relay is turned off
if((millis() - lastDebounceTime) > debounceDelay && relayState == HIGH){
digitalWrite(relay, HIGH);
relayState = LOW;
Serial.println("OFF");
}
delay(50);
}
void detectMotion() {
Serial.println("Motion");
if(relayState == LOW){
digitalWrite(relay, LOW);
}
relayState = HIGH;
Serial.println("ON");
lastDebounceTime = millis();
}
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Demonstration
Now, when movement is detected your lamp lights up.
Wrapping up
Controlling a relay module with the Arduino is as simple as controlling an output.
With the relay module you can control almost any AC electronics appliance (not
just lamps).
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nRF24L01
These RF modules are very popular among the Arduino tinkerers. The nRF24L01 is
used on a wide variety of applications that require wireless control. They
are transceivers which means that each module can transmit and receive data.
These modules are very cheap and you can use them with any microcontroller (MCU).
Specifications nRF24L01 – 2.4GHz RF Transceiver
Low cost single-chip 2.4GHz GFSK RF transceiver IC
Range with Antenna: 250Kb rate (Open area) >1000 meter
Power: Ultra low power consumption
Input Voltage: 3.3V
Pins: 5V tolerant
Price: $2
Where to buy?
Click the link below to compare these modules at different stores and find the best
price:
nRF24L01/2.4GHz RF
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Arduino with nRF24L01
You need the following components to complete the instructions in this example:
Figure
Name
Arduino UNO
2x nRF24L01
Breadboard
Jumper Wires
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Library
For this project you need the RadioHead library.
1. Click here to download the RadioHead library
2. Unzip the .zip folder and you should get RadioHead-1.46 folder.
3. Rename your folder from RadioHead-1.46 to RadioHead.
4. Move the RadioHead folder to your Arduino IDE installation libraries folder.
5. Finally, re-open your Arduino IDE.
The RadioHead library is great and it works with almost all RF modules in the market.
You can read more about this project here.
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Pinout
Here’s the top view of NRF24L01
Client circuit
WARNING
Input voltage is of 1.9V~3.6V, do not exceed this voltage, otherwise it will fry
your module.
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Follow the circuit above for your client. Then upload the code below which can be
found in your Arduino IDE (after installing the RadioHead library).
Go to File Examples RadioHead nrf24 nrf24_client.
// nrf24_client
#include
#include
// Singleton instance of the radio driver
RH_NRF24 nrf24;
// RH_NRF24 nrf24(8, 7); // use this to be electrically compatible with Mirf
// RH_NRF24 nrf24(8, 10);// For Leonardo, need explicit SS pin
// RH_NRF24 nrf24(8, 7); // For RFM73 on Anarduino Mini
void setup()
{
Serial.begin(9600);
while (!Serial)
; // wait for serial port to connect. Needed for Leonardo only
if (!nrf24.init())
Serial.println("init failed");
// Defaults after init are 2.402 GHz (channel 2), 2Mbps, 0dBm
if (!nrf24.setChannel(1))
Serial.println("setChannel failed");
if (!nrf24.setRF(RH_NRF24::DataRate2Mbps, RH_NRF24::TransmitPower0dBm))
Serial.println("setRF failed");
}
void loop()
{
Serial.println("Sending to nrf24_server");
// Send a message to nrf24_server
uint8_t data[] = "Hello World!";
nrf24.send(data, sizeof(data));
nrf24.waitPacketSent();
// Now wait for a reply
uint8_t buf[RH_NRF24_MAX_MESSAGE_LEN];
uint8_t len = sizeof(buf);
if (nrf24.waitAvailableTimeout(500))
{
// Should be a reply message for us now
if (nrf24.recv(buf, &len))
{
Serial.print("got reply: ");
Serial.println((char*)buf);
}
else
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{
Serial.println("recv failed");
}
}
else
{
Serial.println("No reply, is nrf24_server running?");
}
delay(400);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/nrf24_client.ino
Server circuit
WARNING
Input voltage is of 1.9V~3.6V, do not exceed this voltage, otherwise it will fry
your module.
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Follow the circuit above for your server. Then upload the code below which can be
found in your Arduino IDE (after installing the RadioHead library).
Go to File Examples RadioHead nrf24 nrf24_server.
// nrf24_server
#include
#include
// Singleton instance of the radio driver
RH_NRF24 nrf24;
// RH_NRF24 nrf24(8, 7); // use this to be electrically compatible with Mirf
// RH_NRF24 nrf24(8, 10);// For Leonardo, need explicit SS pin
// RH_NRF24 nrf24(8, 7); // For RFM73 on Anarduino Mini
void setup()
{
Serial.begin(9600);
while (!Serial)
; // wait for serial port to connect. Needed for Leonardo only
if (!nrf24.init())
Serial.println("init failed");
// Defaults after init are 2.402 GHz (channel 2), 2Mbps, 0dBm
if (!nrf24.setChannel(1))
Serial.println("setChannel failed");
if (!nrf24.setRF(RH_NRF24::DataRate2Mbps, RH_NRF24::TransmitPower0dBm))
Serial.println("setRF failed");
}
void loop()
{
if (nrf24.available())
{
// Should be a message for us now
uint8_t buf[RH_NRF24_MAX_MESSAGE_LEN];
uint8_t len = sizeof(buf);
if (nrf24.recv(buf, &len))
{
//
NRF24::printBuffer("request: ", buf, len);
Serial.print("got request: ");
Serial.println((char*)buf);
// Send a reply
uint8_t data[] = "And hello back to you";
nrf24.send(data, sizeof(data));
nrf24.waitPacketSent();
Serial.println("Sent a reply");
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}
else
{
Serial.println("recv failed");
}
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/nrf24_server.ino
Demonstration
In this project the client is sending a message “Hello World!” to the server via RF and
the server is sending back the following message “And hello back to you”. Those
messages are being displayed in the serial monitor. Here’s what you should see in
your serial monitor and terminal windows (see Figure below).
Note: On the left window, I’m establishing a serial communication with PuTTY.org.
On the right window, I’m using the Arduino IDE Serial Monitor.
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Wrapping up
You need to have some realistic expectations when using this module. They work
very well when the receiver and transmitter are quite close to each other. If you
separate them too far, you’ll lose the communication.
The communication range will vary. It depends on how much noise in your
environment, if there’s any obstacles and if you’re using an external antenna.
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433 MHz Transmitter/Receiver
These RF modules are very popular among the Arduino tinkerers. The 433MHz is
used on a wide variety of applications that require wireless control.
These modules are very cheap, and you can use them with any microcontroller (MCU).
Specifications RF 433MHz Receiver
Frequency Range: 433.92 MHz
Modulation: ASK
Input Voltage: 5V
Price: $1 to $2
Specifications RF 433MHz Transmitter
Frequency Range: 433.92MHz
Input Voltage: 3-12V
Price: $1 to $2
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
433 MHz Transmitter/Receiver
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Arduino with RF 433MHz Modules
This is a simple example to transmit a message via RF.
Library download
Here’s the library you need for this project:
1. Download the RadioHead library
2. Unzip the RadioHead library
3. Install the RadioHead library in your Arduino IDE
4. Restart your Arduino IDE
The RadioHead library is great and it works with almost all RF modules in the market.
You can read more about this project here.
Receiver circuit
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Follow the circuit above for your receiver. Then upload the code below.
#include
#include // Not actualy used but needed to compile
RH_ASK driver;
void setup()
{
Serial.begin(9600);
// Debugging only
if (!driver.init())
Serial.println("init failed");
}
void loop()
{
uint8_t buf[12];
uint8_t buflen = sizeof(buf);
if (driver.recv(buf, &buflen)) // Non-blocking
{
int i;
// Message with a good checksum received, dump it.
Serial.print("Message: ");
Serial.println((char*)buf);
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/433MHz/receiver.ino
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Transmitter circuit
Follow the circuit above for your transmitter. Then upload the code below.
#include
#include // Not actually used but needed to compile
RH_ASK driver;
void setup()
{
Serial.begin(9600);
// Debugging only
if (!driver.init())
Serial.println("init failed");
}
void loop()
{
const char *msg = "Hello World!";
driver.send((uint8_t *)msg, strlen(msg));
driver.waitPacketSent();
delay(1000);
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/433MHz/transmitter.ino
Demonstration
In this project the transmitter is sending a message “Hello World!” to the receiver via
RF. Those messages are being displayed in the serial monitor from the
receiver. Here’s what you should see in your Arduino IDE serial monitor.
Wrapping up
You need to have some realistic expectations when using this module. They work
very well when the receiver and transmitter are close to each other. If you separate
them too far you’ll lose the communication.
The communication range will vary. It depends on how much voltage that
you’re supplying to your transmitter module, RF noise in your environment and if
you’re using an external antenna.
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OLED Display
The OLED display is shown in the following figure:
It is a very small display made of 128 by 64 individual OLED pixels and no backlight is
required. That OLED display is monochrome (white color), but there are other
models with several colors.
This display uses I2C communication. This means that it communicates with the
Arduino using just 2 pins.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
0.96 inch OLED display
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Pin wiring
OLED Pin
Wiring to Arduino Uno
Vin
5V
GND
GND
SCL
A5
SDA
A4
If you’re using other Arduino board rather than the UNO, check out what are their
SCL and SDA pins.
Nano: SDA (A4); SCL(A5);
MEGA: SDA (20); SCL(21);
Leonardo: SDA (20); SCL(21);
Libraries
To control the OLED display you’ll need the “adafruit_GFX.h” library and the
“adafruit_SSD1306.h” library.
Installing the adafruit_GFX library
1. Click here to download the adafruit GFX library. You should have a .zip
folder in your Downloads folder
2. Unzip the .zip folder and you should get Adafruit-GFX-Library-master folder
3. Rename
your
folder
from
Adafruit-GFX-Library-
master to Adafruit_GFX_Library.
4. Move the Adafruit_GFX_Library folder to your Arduino IDE installation
libraries folder
5. Finally, re-open your Arduino IDE
Installing the adafruit_SSD1306 library
1. Click here to download the adafruit_SSD1306 library. You should have a .zip
folder in your Downloads folder
2. Unzip the .zip folder and you should get Adafruit-GFX-Library-master folder
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3. Rename your folder from Adafruit_SSD1306-master to Adafruit_SSD1306
4. Move the Adafruit_SSD1306 folder to your Arduino IDE installation libraries
folder
5. Finally, re-open your Arduino IDE
Tips for writing text using these libraries
Here’s some functions that will help you handle the OLED display library to write text
or draw simple graphics.
display.clearDisplay() – all pixels are off
display.drawPixel(x,y, color) – plot a pixel in the x,y coordinates
display.setTextSize(n) – set the font size, supports sizes from 1 to 8
display.setCursor(x,y) – set the coordinates to start writing text
display.print(“message”) – print the characters at location x,y
Example: Display temperature and humidity
In this example you will display the temperature and humidity in the OLED display.
The aim of this project is to get familiar with the OLED display.
The temperature and humidity will be measured using the DHT11 temperature and
humidity sensor. If you’re not familiar with the DHT11 sensor we recommend that
you check the DHT11/22 guide.
Figure
Name
Arduino UNO
OLED Display
DHT11
Breadboard
10kΩ Resistor
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Jumper Wires
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Schematics
Assemble all the parts as in the schematics below.
Code
Make sure you’ve installed the necessary libraries to control the OLED display. You
also need to install the DHT library. Check the DHT11/22 temperature and humidity
sensor guide.
Then, you can upload the following code.
/*
* Random Nerd Tutorials - Rui Santos
* Complete Project Details http://randomnerdtutorials.com
*/
#include
#include
#include
#include
#define DHTPIN 2
// what pin we're connected to
#define DHTTYPE DHT11
// DHT 11
#define OLED_RESET 4
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Adafruit_SSD1306 display(OLED_RESET);
// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);
void setup()
{
Wire.begin();
dht.begin(); // initialize dht
display.begin(SSD1306_SWITCHCAPVCC, 0x3C);// initialize with the I2C addr 0x3C (for
the 128x32)(initializing the display)
Serial.begin(9600);
}
void displayTempHumid(){
delay(2000);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
// Read temperature as Celsius
float t = dht.readTemperature();
// Read temperature as Fahrenheit
float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t) || isnan(f)) {
display.clearDisplay(); // clearing the display
display.setTextColor(WHITE); //setting the color
display.setTextSize(1); //set the font size
display.setCursor(5,0); //set the cursor coordinates
display.print("Failed to read from DHT sensor!");
return;
}
display.clearDisplay();
display.setTextColor(WHITE);
display.setTextSize(1);
display.setCursor(0,0);
display.print("Humidity: ");
display.print(h);
display.print(" %\t");
display.setCursor(0,10);
display.print("Temperature: ");
display.print(t);
display.print(" C");
display.setCursor(0,20);
display.print("Temperature: ");
display.print(f);
display.print(" F");
}
void loop()
{
displayTempHumid();
display.display();
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/display_tempreature_and_humidity_in_oled.ino
Demonstration
Here’s the OLED display in action after uploading the code.
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8x8 Dot Matrix
The dot matrix that we’re going to use in this guide is an 8×8 matrix which means
that it has 8 columns and 8 rows, so it contains a total of 64 LEDs.
The MAX7219 chip makes it easier to control the dot matrix, by just using 3 digital
pins of the Arduino board.
I think the best option is to buy the dot matrix with the MAX7219 chip as a module,
it will simplify the wiring.
You can control more than one matrix at a time. For that you just need to connect
them to each other, as they have pins in both sides to extend the dot matrix.
Where to buy?
Click the link below to compare the matrix at different stores and find the best price:
MAX7219 LED matrix
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Pin wiring
You only need to connect 5 pins from the dot matrix to your Arduino board. The
wiring is straightforward:
Dot Matrix Pin
Wiring to Arduino Uno
GND
GND
VCC
5V
DIN
Digital pin
CS
Digital pin
CLK
Digital pin
Libraries
For making it easier to control the dot matrix, you need to download and install in
your Arduino IDE the LedControl library. To install the library follow these steps:
1. Click here to download the LedControl library. You should have a .zip folder
in your Downloads
2. Unzip the .zip folder and you should get LedControl-master folder
3. Rename your folder from LedControl-master to LedControl
4. Move the LedControl folder to your Arduino IDE installation libraries folder
5. Finally, re-open your Arduino IDE
Using the LedControl library functions
The easiest way to display something on the dot matrix is by using the
functions setLed(), setRow() or setColumn(). These functions allow you to control
one single led, one row or one column at a time. Here’s the parameters for each
function:
setLed(addr, row, col, state)
addr is the address of your matrix, for example, if you have just 1 matrix,
the addr will be zero.
row is the row where the LED is located
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col is the column where the LED is located
state
o It’s true or 1 if you want to turn the led on
o It’s false or 0 if you want to switch it off
setRow(addr, row, value)
setCol(addr, column, value)
Example: Displaying icons on the dot matrix
In this example, you’ll display several faces sequentially on a dot matrix: a happy, a
neutral, and a sad face.
Index
As previously stated, this matrix has 8 columns and 8 rows. Each one is indexed from
0 to 7. Here’s a figure for better understanding:
If you want to display something in the matrix, you just need to know if in a
determined row or column, the LEDs that are on or off.
For example, if you want to display a happy face, here’s what you need to do:
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Schematic
Connect the dot matrix as in the diagram below.
Here’s a simple sketch that displays three types of faces: a sad face, a neutral face
and a happy face. Upload the following code to your board:
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/*
Created by Rui Santos
All the resources for this project:
http://randomnerdtutorials.com/
*/
#include "LedControl.h"
#include "binary.h"
/*
DIN connects to pin 12
CLK connects to pin 11
CS connects to pin 10
*/
LedControl lc=LedControl(12,11,10,1);
// delay time between faces
unsigned long delaytime=1000;
// happy face
byte hf[8]=
{B00111100,B01000010,B10100101,B10000001,B10100101,B10011001,B01000010,B00111100};
// neutral face
byte nf[8]={B00111100,
B01000010,B10100101,B10000001,B10111101,B10000001,B01000010,B00111100};
// sad face
byte sf[8]=
{B00111100,B01000010,B10100101,B10000001,B10011001,B10100101,B01000010,B00111100};
void setup() {
lc.shutdown(0,false);
// Set brightness to a medium value
lc.setIntensity(0,8);
// Clear the display
lc.clearDisplay(0);
}
void drawFaces(){
// Display sad face
lc.setRow(0,0,sf[0]);
lc.setRow(0,1,sf[1]);
lc.setRow(0,2,sf[2]);
lc.setRow(0,3,sf[3]);
lc.setRow(0,4,sf[4]);
lc.setRow(0,5,sf[5]);
lc.setRow(0,6,sf[6]);
lc.setRow(0,7,sf[7]);
delay(delaytime);
// Display neutral face
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lc.setRow(0,0,nf[0]);
lc.setRow(0,1,nf[1]);
lc.setRow(0,2,nf[2]);
lc.setRow(0,3,nf[3]);
lc.setRow(0,4,nf[4]);
lc.setRow(0,5,nf[5]);
lc.setRow(0,6,nf[6]);
lc.setRow(0,7,nf[7]);
delay(delaytime);
// Display happy face
lc.setRow(0,0,hf[0]);
lc.setRow(0,1,hf[1]);
lc.setRow(0,2,hf[2]);
lc.setRow(0,3,hf[3]);
lc.setRow(0,4,hf[4]);
lc.setRow(0,5,hf[5]);
lc.setRow(0,6,hf[6]);
lc.setRow(0,7,hf[7]);
delay(delaytime);
}
void loop(){
drawFaces();
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/dot_matrix_faces.ino
In the end, you’ll have something like this:
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WS2812B Addressable RGB LED Strip
The WS2812B LED strip is an addressable RGB LED strip. The information in this
guide also works with other similar LED strips, such as strips of the WS28XX family,
Neopixel strip and others.
The WS2812B addressable LED strip comes in several varieties that differ in size,
sealant or LED density. Choose the one that best fits your purposes.
Where to buy?
Click the link below to compare the LED strip at different stores and find the best
price:
WS2812B addressable RGB LED Strip
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WS2812B Addressable RGB LED strip
In the preceding figure you can see my WS2812B LED strip. It is 5 meters long and
the LEDs are enclosed in a weatherproof silicone.
In my opinion, this is the coolest type of LED strips. You can control
the brightness and the color of each LED individually, which allows you to produce
amazing and complex effects in a simple way.
This LED strip is made by WS2812B LEDs wired in series. These LEDs have an IC built
right into the LED. This allows a communication via a one-wire interface. This means
that you can control lots of LEDs using just one digital pin of your Arduino.
In the following figure you can see the chip inside the LED. The LED is an RGB LED
and works like so.
This kind of strips are very flexible and can be cut to any length you want. As you can
see, the strip is divided into segments, and each segment contains one RGB LED.
You can adjust its size by cutting the strip with a scissors in the right place (the proper
places to cut the strip are marked).
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These strips come with connectors at each end. I’ve decided to cut the connectors,
and solder header pins. It’s handier if you want to connect the strip to an Arduino
or to a breadboard.
Powering the WS2812B LED Strip
The LED strip should be powered using a 5V power source. At 5V, each LED draws
about 50mA, when set to its full brightness. This means that for every 30 LEDs, the
strip may draw as much as 1.5 A. Make sure you select a power source that
matches the strip’s needs.
If you end up using an external supply, don’t forget to connect the power supply
ground to the Arduino ground.
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Schematics
In this example, the WS2812B LED strip will be powered using the 5V Arduino pin. In
my case, I’m controlling 14 LEDs. Bear in mind that if you want to control many LEDs,
you’ll need to use an external power supply.
Useful tips:
Connect a capacitor with a capacitance between 100uF and 1000uF from
power to ground to smooth out the power supply.
Add a 220 or 470 Ohm resistor between the Arduino digital output pin and
the strip data input pin to reduce noise on that line.
Make your wires between the Arduino, power supply and the strip as short
as possible to minimize voltage loss.
If your strip gets damaged and doesn’t work, check if the first LED is broken.
If so, cut it, resolder the header pins, and it should be working again.
Code
To control the WS2812B LED strip, you’ll need to download the FastLED library.
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Installing the FastLED library
1. Click here to download the FastLED library. You should have a .zip folder in
your Downloads folder
2. Unzip the .zip folder and you should get FastLED-master folder
3. Rename your folder from FastLED-master to FastLED
4. Move the FastLED folder to your Arduino IDE installation libraries folder
5. Finally, re-open your Arduino IDE
After installing the needed library, upload the following code to your Arduino board
(this is an example sketch provided in the library examples folder). Go to File
Examples FastLED ColorPalette or copy the code below.
Note: you have to change #define NUM_LEDS to the number of LEDs that your strip
currently has.
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Arduino_WS2812B_Color_Palette.ino
Demonstration
In the end, this is what you’ll have. Amazing effects like this one:
Or this one:
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And so on (…)
Using an LED Strip Case
These strips usually come with a removable tape, so that you can stick them
wherever you want. The problem is that they don’t stick very well, so chances are that
you’ll find your strip in the floor the following day.
The solution: I found this strip case that diffuses the light well and you can screw it
to a shelf, for example, if you want a permanent solution.
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Membrane Keypad
A keypad allows you to interact with a microcontroller. You can salvage these
keypads from old telephones or you can purchase them from most electronics stores
for less than $2. They come in wide variety of shapes and sizes. The most common
sizes are 3×4 and 4×4 and you can get keypads with words, letters and numbers
written on the keys.
These keypads very popular among the Arduino tinkerers. They are very cheap, and
you can use them with any microcontroller (MCU). You can even create your own
keypad from scratch.
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Membrane keypad
How it works?
A membrane keypad is a matrix consisting of rows and columns. Each key is
assigned to a certain row and column (see the picture below).
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On a 12 button keypad you have 4 rows and 3 columns. The first key would make a
link between Row 1 and Column 1 (R1C1). 2 would be R1C2, 3 R1C3, * R4C1, 9 R3C3
and so on.
Schematic
Follow the next schematics. If your keypad is different from the one below, search
for the datasheet online.
Library download
1. Click here to download the Keypad library . You should have a .zip folder in
your Downloads folder
2. Unzip the .zip folder and you should get Keypad folder
3. Move the Keypad folder to your Arduino IDE installation libraries folder
4. Finally, re-open your Arduino IDE
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Code
If your keypad doesn’t work with code below you might have to change the
connections from the previous schematics. You have to make sure you follow your
keypad’s datasheet.
Note: If your keypad has more keys you can change lines 3 and 4 to add the right
number of rows and columns. Then in line 5 you can change the array to match your
keypad keys.
#include "Keypad.h"
const byte ROWS = 4; // number of rows
const byte COLS = 3; // number of columns
char keys[ROWS][COLS] = {
{'1','2','3'},
{'4','5','6'},
{'7','8','9'},
{'#','0','*'}
};
byte rowPins[ROWS] = {8, 7, 6, 5}; // row pinouts of the keypad R1 = D8, R2 = D7, R3 =
D6, R4 = D5
byte colPins[COLS] = {4, 3, 2};
// column pinouts of the keypad C1 = D4, C2 = D3,
C3 = D2
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
void setup(){
Serial.begin(9600);
}
void loop(){
char key = keypad.getKey();
if (key != NO_KEY)
Serial.println(key);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/Arduino_with_Keypad.ino
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Demonstration
In this project when you press a key, its value is displayed on the Arduino serial
monitor. Here’s what you should see in your Arduino IDE serial monitor when you
start pressing the keypad keys.
Wrapping up
Now you can create an interface for your Arduino using a keypad. You can also add
an LCD to this project.
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1.8 TFT Display
The 1.8 TFT is a colorful display with 128 x 160 color pixels. The display can load
images from an SD card – it has an SD card slot at the back. The following figure
shows the screen front and back view.
This module uses SPI communication – see the wiring below. To control the display
we’ll use the TFT library, which is already included with Arduino IDE 1.0.5 and later.
Where to buy?
Click the link below to compare the display at different stores and find the best price:
1.8 TFT display
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Pin wiring
The table below shows the 1.8 TFT wiring to Arduino UNO.
1.8 TFT Display Pin
Wiring to Arduino Uno
LED
3.3 V
SCK
13
SDA
11
A0 or DC
9
RESET
8
CS
10
GND
GND
Note: different Arduino boards have different SPI pins. If you’re using another
Arduino board, check the Arduino official documentation.
Initializing the display
The TFT display communicates with the Arduino via SPI communication, so you need
to include the SPI library on your code. We also use the TFT library to write and draw
on the display.
#include
#include
Then, you need to define the CS, A0 (or DC) and RST pins:
#define cs 10
#define dc 9
#define rst 8
Create an instance of the library called TFTscreen:
TFT TFTscreen = TFT(cs, dc, rst);
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Finally, in the setup(), you need to initialize the library:
TFTscreen.begin();
Display text
To write text on the display, you can customize the screen background color, font
size and color.
To set the background color, use:
TFTscreen.background(r, g, b);
In which, r, g and b are the RGB values for a given color.
To choose font color use:
TFTscreen.stroke(r, g, b);
To set the font size:
TFTscreen.setTextSize(2);
You can increase or decrease the number given as argument, to increase or decrease
font size.
Finally, to draw text on the display you use the following line:
TFTscreen.text("Hello, World!", x, y);
In which “Hello, World!” is the text you want to display and the (x, y) coordinate is
the location where you want to start display text on the screen.
Code
The following example displays “Hello, World!” in the middle of the screen and
changes the font color every 200 milliseconds.
Copy the following code to your Arduino IDE and upload it to your Arduino board.
/*
* Rui Santos
* Complete Project Details http://randomnerdtutorials.com
*/
// include TFT and SPI libraries
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#include
#include
// pin definition for Arduino UNO
#define cs
10
#define dc
9
#define rst
8
// create an instance of the library
TFT TFTscreen = TFT(cs, dc, rst);
void setup() {
//initialize the library
TFTscreen.begin();
// clear the screen with a black background
TFTscreen.background(0, 0, 0);
//set the text size
TFTscreen.setTextSize(2);
}
void loop() {
//generate a random color
int redRandom = random(0, 255);
int greenRandom = random (0, 255);
int blueRandom = random (0, 255);
// set a random font color
TFTscreen.stroke(redRandom, greenRandom, blueRandom);
// print Hello, World! in the middle of the screen
TFTscreen.text("Hello, World!", 6, 57);
// wait 200 miliseconds until change to next color
delay(200);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/tft/write_text.ino
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Here’s your “Hello, World!” text on the 1.8 TFT display.
Display shapes
The TFT library provides useful functions to draw shapes on the display:
TFTscreen.point(x, y) – displays a point at the (x, y) coordinate
TFTscreen.line(xStart, yStart, xEnd, yEnd) – draws a line that starts
at (xStart, yStart) and ends at (xEnd, yEnd)
TFTscreen.rect(xStart, yStart, width, height) – draws a rectangle
with the top left corner at (xStart, yStart) with the defined width and
height
TFTscreen.circle(x, y, radius) – draws a circle with center at (x, y) with
the specified radius
Code
The following example displays several shapes. Every time the code goes through the
loop, the shapes change color.
Copy the following code to your Arduino IDE and upload it to your Arduino board.
/*
* Rui Santos
* Complete Project Details http://randomnerdtutorials.com
*/
// include TFT and SPI libraries
#include
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#include
// pin definition for Arduino UNO
#define cs
10
#define dc
9
#define rst
8
// create an instance of the library
TFT TFTscreen = TFT(cs, dc, rst);
void setup() {
//initialize the library
TFTscreen.begin();
// clear the screen with a black background
TFTscreen.background(0, 0, 0);
}
void loop() {
//generate a random color
int redRandom = random(0, 255);
int greenRandom = random (0, 255);
int blueRandom = random (0, 255);
// set the color for the figures
TFTscreen.stroke(redRandom, greenRandom, blueRandom);
// light up a single point
TFTscreen.point(80,64);
// wait 200 miliseconds until change to next figure
delay(500);
// draw a line
TFTscreen.line(0,64,160,64);
delay(500);
//draw a square
TFTscreen.rect(50,34,60,60);
delay(500);
//draw a circle
TFTscreen.circle(80,64,30);
delay(500);
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//erase all figures
TFTscreen.background(0,0,0);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/tft/draw_shapes.ino
Here’s the shapes on the display:
Display images
The 1.8 TFT display can load images from the SD card. To read from the SD card you
use the SD library, already included in the Arduino IDE software. Follow the next
steps to display an image on the display:
1) Solder header pins for the SD card. There are four pins opposite to the
display pins, as shown in figure below.
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2) The display can load images bigger or smaller than the display size (160 x
128 px), but for better results, edit your image size to 160 x 128 px.
3) The image should be in .bmp format. To do that, you can use a photo editing
software and save the image as .bmp format.
4) Copy the image to the SD card and insert it on the SD card slot at the back
of the display.
5) Wire the SD card pins to the Arduino by following the table below:
SD card pins on TFT display
Wiring to Arduino Uno
CS
4
MOSI
11
MISO
13
SCK
12
Both the display and the SD card work with SPI communication, so you’ll have pins
on the Arduino with two connections.
6) In the Arduino IDE go to File Examples TFT Arduino TFTBitmaLogo.
7) Edit the code, so that it searches for your image. Replace the “arduino.bmp” with
the name of your image:
// now that the SD card can be access, try to load the image
file
logo = TFTscreen.loadImage("arduino.bmp");
8) Upload the code to your Arduino.
Note: some people find issues with this display when trying to read from the SD card.
We don’t know why that happens. In fact, we tested a couple of times and it worked
well, and then, when we were about to record to show you the final result, the display
didn’t recognized the SD card anymore – we’re not sure if it’s a problem with the SD
card holder that doesn’t establish a proper connection with the SD card. However,
we are sure these instructions work, because we’ve tested them before.
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Wrapping up
In this guide we’ve shown you how to use the 1.8 TFT display with the Arduino: display
text, draw shapes and display images. You can easily add a nice visual interface to
your projects using this display.
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SIM900 GSM GPRS Shield
The SIM900 GSM GPRS Shield is shown in figure below.
GSM stands for Global System for Mobile Communications and is the global standard
for mobile communications.
GPRS stands for General Packet Radio Service. GPRS is a mobile service on the 2G
and 3G cellular communication.
Applications:
The GSM GPRS shield is particularly useful as it allows to:
Connect to the Internet over GPRS network
Send and receive SMS
Place and receive phones calls
Its capabilities make it perfect for projects with Arduino like:
Remote control of electronic appliances – sending an SMS to turn something
on;
Receive notifications – send SMS to your cell phone if movement is detected in
your house;
Receive sensor data – send periodic SMS to your cell phone with daily weather
data.
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Features
Here’s some of the most important features of the shield:
Compatible with Arduino and clones
Based on SIM900 module from SIMCOM
Allows you to send SMS, MMS, GPRS and Audio via UART using AT commands.
It has 12 GPIOs, 2 PWMs and built-in ADC of the SIM900 module
Quad Band: 850; 900; 1800 and 1900 MHZ, so it should work in all countries
with GSM (2G) networks
Control via AT commands
Supports RTC (real time clock) – it has a holder for a 3V CR1220 battery at the
back
Has microphone and headphone jacks for phone calls
Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
SIM900 GSM/GPRS Shield
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Preliminary steps
Before getting started with your SIM900 GSM GPRS module, you need to consider
some aspects about the SIM card and the shield power supply.
GSM coverage
Ensure you have coverage on a GSM 850 MHz, GSM 900 MHz, DCS 1800 MHz or PCS
1900 MHz network. By GSM we mean 2G.
Prepaid SIM Card
We recommend that you use a prepaid plan or a plan with unlimited SMS for testing
purposes. Otherwise, if something goes wrong, you may need to pay a huge bill for
hundreds of SMS text messages sent by mistake. In this tutorial we’re using a prepaid
plan with unlimited SMS.
The shield uses the original SIM card size, not micro or nano. If you have micro or
nano you may consider getting a SIM card size adapter.
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Turn off the PIN lock
To use the SIM card with the shield, you need to turn off the pin lock. The easiest way
to do this, is to insert the SIM card in your smartphone and turn off the pin lock in
the phone security settings.
In my case, I needed to go through: Settings Advanced Settings Security SIM
lock and turn off the Lock SIM card with pin.
Getting the right power supply
The shield has a DC socket for power as shown in figure below.
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Next to the power jack there is a toggle switch to select the power source. Next to
the toggle switch on the board, there is an arrow indicating the toggle position to use
an external power supply – move the toggle switch to use the external power supply
as shown above.
To power up the shield, it is advisable to use a 5V power supply that can provide 2A
as the one shown below. It can also be powered with 9V 1A, or 12V 1A.
You can find the right power adapter for this shield here. Make sure you select the
model with 5V and 2A.
SIM900 GSM GPRS Shield Hardware
The figure below shows the back of the shield. It has a holder for the SIM card and
for a 3V CR1220 battery for the RTC (real time clock).
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The figure below shows the shield most important components on the board that
you need to pay attention to.
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Getting started
1) Insert the SIM card into the SIM card holder – make sure you’ve read the
preliminary steps in the previous section.
2) Make sure the antenna is well connected.
3) On the serial port select, make sure the jumper cap is connected as shown in figure
below to use software serial.
4) Power the shield using an external 5V power supply. Make sure you select the
external power source with the toggle switch next to the DC jack.
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5) To power up/down the shield press the power key for about 2 seconds.
6) Then, the Status LED will light up and the NetLight LED will blink every 800 ms until
it finds the network. When it finds the network, the NetLight LED will start blinking
every three seconds.
Note: you can automatically turn on the shield via software. See how to do that in
the Automatically turn on the shield section, after the code examples.
7) You can test if the shield is working properly by sending AT commands from the
Arduino IDE using an FTDI programmer – as we’ll shown later in this guide.
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SIM900 AT commands
set the SIM900 to text mode: AT+CMGF=1\r
send SMS to a number: AT+CMGS=PHONE_NUMBER (in international
format)
read the first SMS from the inbox: AT+CMGR=1\r
read the second SMS from the inbox: AT+CMGR=2\r
read all SMS from the inbox: AT+CMGR=ALL\r
call to a number: ATDP+ PHONE_NUMBER (in international format)
hang up a call: ATH
receive an incoming call: ATA
For more information, you can check the SIM900 AT commands
manual here.
Testing the Shield with FTDI programmer
To test if everything is working properly, you can test the shield by sending AT
commands from the Arduino IDE serial monitor. For that, you need an FTDI
programmer as the one shown in figure below. You can get an FTDI programmer like
this here.
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1) Connect the FTDI programmer to the GSM shield as shown in figure below.
2) Open the Arduino IDE and select the right COM port.
3) Open the Serial monitor.
4) Select 19200 baud rate – the shield default setting is 19200 – and Carriage return.
Write AT at the box highlighted in red and then press enter. See figure below.
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5) The shield will respond with OK, if everything is working properly.
Connecting the Shield to Arduino
Connect the shield to the Arduino as shown in the schematic diagram below.
Sending an SMS
To send an SMS, upload the code below to your Arduino board.
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/*********
Complete project details at http://randomnerdtutorials.com
*********/
#include
// Configure software serial port
SoftwareSerial SIM900(7, 8);
void setup() {
// Arduino communicates with SIM900 GSM shield at a baud rate of 19200
// Make sure that corresponds to the baud rate of your module
SIM900.begin(19200);
// Give time to your GSM shield log on to network
delay(20000);
// Send the SMS
sendSMS();
}
void loop() {
}
void sendSMS() {
// AT command to set SIM900 to SMS mode
SIM900.print("AT+CMGF=1\r");
delay(100);
// REPLACE THE X's WITH THE RECIPIENT'S MOBILE NUMBER
// USE INTERNATIONAL FORMAT CODE FOR MOBILE NUMBERS
SIM900.println("AT + CMGS = \"+XXXXXXXXXXXX\"");
delay(100);
// REPLACE WITH YOUR OWN SMS MESSAGE CONTENT
SIM900.println("Message example from Arduino Uno.");
delay(100);
// End AT command with a ^Z, ASCII code 26
SIM900.println((char)26);
delay(100);
SIM900.println();
// Give module time to send SMS
delay(5000);
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/GSM/sendSMS.ino
In this code, you start by including the SoftwareSerial.h library and create a
software serial port on pins 7 and 8 (Pin 7 is being set as RX and 8 as TX).
#include
SoftwareSerial SIM900(7, 8);
The sendSMS() function created is what actually sends the SMS. This function uses
the AT commands: AT+CMGF=1\r and AT + CMGS.
You need to change the recipient’s mobile number at: (replace the X‘s with the
recipient’s phone number)
SIM900.println("AT + CMGS = \"++++++++++++++"");
The recipient’s mobile number should be in international format.
Then, at the following line you can edit the text you want to send.
// REPLACE WITH YOUR OWN SMS MESSAGE CONTENT
SIM900.println("Message example from Arduino Uno.")
Reading received SMS
To read incoming SMS, upload the code below to your Arduino. After uploading, wait
20 seconds for the shield to establish communication. Then, test the script by
sending an SMS to the shield SIM card number. The SMS is shown on the Arduino
serial monitor – baud rate: 19200.
/*********
Complete project details at http://randomnerdtutorials.com
*********/
#include
// Configure software serial port
SoftwareSerial SIM900(7, 8);
//Variable to save incoming SMS characters
char incoming_char=0;
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void setup() {
// Arduino communicates with SIM900 GSM shield at a baud rate of 19200
// Make sure that corresponds to the baud rate of your module
SIM900.begin(19200);
// For serial monitor
Serial.begin(19200);
// Give time to your GSM shield log on to network
delay(20000);
// AT command to set SIM900 to SMS mode
SIM900.print("AT+CMGF=1\r");
delay(100);
// Set module to send SMS data to serial out upon receipt
SIM900.print("AT+CNMI=2,2,0,0,0\r");
delay(100);
}
void loop() {
// Display any text that the GSM shield sends out on the serial monitor
if(SIM900.available() >0) {
//Get the character from the cellular serial port
incoming_char=SIM900.read();
//Print the incoming character to the terminal
Serial.print(incoming_char);
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/GSM/receiveSMS.ino
In this code, you set the module to send the SMS data to the serial output:
SIM900.print("AT+CNMI=2,2,0,0,0\r");
You store the incoming characters from the SMS message on the incoming_char
variable. You read the chars using the SIM900.read() function.
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Making a phone call
To make a phone call, upload the following code to your Arduino.
Don’t forget to edit the code with the phone number you want to call.
/*********
Complete project details at http://randomnerdtutorials.com
*********/
#include
// Configure software serial port
SoftwareSerial SIM900(7, 8);
void setup() {
// Arduino communicates with SIM900 GSM shield at a baud rate of 19200
// Make sure that corresponds to the baud rate of your module
SIM900.begin(19200);
// Give time to your GSM shield log on to network
delay(20000);
// Make the phone call
callSomeone();
}
void loop() {
}
void callSomeone() {
// REPLACE THE X's WITH THE NUMER YOU WANT TO DIAL
// USE INTERNATIONAL FORMAT CODE FOR MOBILE NUMBERS
SIM900.println("ATD + +XXXXXXXXX;");
delay(100);
SIM900.println();
// In this example, the call only last 30 seconds
// You can edit the phone call duration in the delay time
delay(30000);
// AT command to hang up
SIM900.println("ATH"); // hang up
}
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/GSM/makePhoneCall.ino
To make the call, you use the callSomeone() function that uses the ATD command.
SIM900.println("ATD + +XXXXXXXXX;");
You need to replace the X‘s (highlighted in red) with the phone number you want to
call.
Don’t forget to connect a microphone and earphones to make the call.
In this code example, the call is hang up after 30 seconds, using the ATH command:
SIM900.println("ATH");
Hanging up after 30 seconds is not very useful, but it works well for an example. The
idea is that you use the ATH command when an event is triggered. For example,
connect a push button to the Arduino, that when pressed sends the ATH command
to hang up the phone.
Answering incoming phone calls
The following code answers incoming calls.
/*********
Complete project details at http://randomnerdtutorials.com
*********/
#include
// Configure software serial port
SoftwareSerial SIM900(7, 8);
char incoming_char=0;
void setup() {
// Arduino communicates with SIM900 GSM shield at a baud rate of 19200
// Make sure that corresponds to the baud rate of your module
SIM900.begin(19200); // for GSM shield
// For serial monitor
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Serial.begin(19200);
// Give time to log on to network.
delay(20000);
SIM900.print("AT+CLIP=1\r"); // turn on caller ID notification
delay(100);
}
void loop() {
// Display any text that the GSM shield sends out on the serial monitor
if(SIM900.available() >0) {
// Get the character from the cellular serial por
// With an incomming call, a "RING" message is sent out
incoming_char=SIM900.read();
//
Check if the shield is sending a "RING" message
if (incoming_char=='R') {
delay(10);
Serial.print(incoming_char);
incoming_char=SIM900.read();
if (incoming_char =='I') {
delay(10);
Serial.print(incoming_char);
incoming_char=SIM900.read();
if (incoming_char=='N') {
delay(10);
Serial.print(incoming_char);
incoming_char=SIM900.read();
if (incoming_char=='G') {
delay(10);
Serial.print(incoming_char);
// If the message received from the shield is RING
// Send ATA commands to answer the phone
SIM900.print("ATA\r");
}
}
}
}
}
}
When someone calls the SIM900 number, it sends a message saying “RING”. To know
if someone is calling you, you can wait for incoming characters from the SIM900 and
then, compare if it was a RING message. That’s what is done in this code. When it
receives a RING message, you send the ATA command to answer the phone.
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SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/GSM/receiveCall.ino
Automatically turn on the shield
Instead of manually pressing the “power” key to turn on the shield, you can
automatically turn on the shield via software.
1) First, you need to solder R13 connections on the shield as shown in the figure
below – highlighted in red.
2) Connect D9 on the shield to the D9 Arduino pin as shown in the schematic below.
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3) Add the following code snippet in the setup() function. This is the equivalent of
pressing the shield “power” button.
digitalWrite(9, HIGH);
delay(1000);
digitalWrite(9, LOW);
delay(5000);
Troubleshooting
Shield doesn’t respond with OK
Check your TX and RX connections to the Arduino. Try repeating the process by
changing the TX with the RX pins.
Also check if you have selected the software serial by placing the jumper cap on the
appropriate place on the serial selector.
Cannot see messages in the serial monitor
To see the messages in the serial monitor, the shield and the Arduino’s serial port
baud rate should be the same. The SIM900 GSM GPRS shield default baud rate is
19200. So, select the Arduino’s baud rate to 19200.
However, if you need to change the shield baud rate, you can send the following AT
command to change it to 19200 or other appropriate baud rate.
AT+IPR=19200
Wrapping up
This tutorial shows you how to send and receive SMS and making and receiving
phone calls with the Arduino. You can apply the concepts learned in this tutorial to
build your own projects to communicate over a cell network.
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SD Card Module
The SD card module is especially useful for projects that require data logging.
The Arduino can create a file in an SD card to write and save data using the SD library.
There are different models from different suppliers, but they all work in a similar way,
using the SPI communication protocol. The module used in this tutorial is the one
shown in figure below (front and back view).
This module works with micro SD card but there are others that work with SD card.
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Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Micro SD card module
Pin wiring
SD card module
Wiring to Arduino Uno
Wiring to Arduino Mega
3.3V or 5V (check module’s
3.3V or 5V (check module’s
VCC
datasheet)
datasheet)
CS
4
53
MOSI
11
51
CLK
13
52
MISO
12
50
GND
GND
GND
Note: different Arduino boards have different SPI pins. If you’re using another
Arduino board, check the Arduino official documentation.
Preparing the SD card
The first step when using the SD card module with Arduino is formatting the SD card
as FAT16 or FAT32. Follow the instructions below.
1) To format the SD card, insert it in your computer. Go to My Computer and right
click on the SD card. Select Format as shown in figure below.
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2) A new window pops up. Select FAT32, press Start to initialize the formatting
process and follow the onscreen instructions.
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Testing the SD card module
Insert the formatted SD card in the SD card module.
Connect the SD card module to the Arduino as shown in the circuit schematic below
or check Pin wiring in previous section.
Note: depending on the module you’re using, the pins may be in a different order.
Code – CardInfo
To make sure everything is wired correctly, and the SD card is working properly, in
the Arduino IDE window go to File Examples SD CardInfo.
Upload the code to your Arduino board. Make sure you have the right board and
COM port selected. Open the Serial Monitor at a baud rate of 9600 and you should
see your SD card information.
If everything is working properly you’ll see a similar message on the serial monitor.
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Read and write to the SD card
The SD library provides useful functions for easily write in and read from the SD card.
To write and read from the SD card, first you need to include the SPI and SD libraries:
#include
#include
You also have to initialize the SD card module at the Chip Select (CS) pin – in our case,
pin 4.
SD.begin(4);
To open a new file in the SD card, you need to create a file object that refers to your
data file. For example:
dataFile = SD.open("data.txt", FILE_WRITE);
The first parameter of this function is the name of the file, data.txt, and
the FILE_WRITE argument enables you to read and write into the file.
This line of code creates a file called data.txt on your SD card. If the data.txt file
already exists, the Arduino will open the file instead of creating another one.
To write data to the currently open file, you use:
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dataFile.write(data);
In which the dataFile is the file object created previously and the data is what you
want to write in the file.
You can also use the print() or println() functions to print data into the file:
dataFile.print(data);
dataFile.println(data); // followed by a new line
To read the data saved on your file:
dataFile.read();
You can only write within a file at once, so you need to close a file before proceeding
to the next one. To close the data.txt file we’ve just created:
SD.close("data.txt");
The argument of this function is the file you want to close, in this case data.txt.
For a complete sketch on how to read and write, in your Arduino IDE go
to File Examples SD ReadWrite.
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TCS3200 Color Sensor
The TCS3200 color sensor can detect a wide variety of colors based on their
wavelength. This sensor is especially useful for color recognition projects such as
color matching, color sorting, test strip reading and much more.
The TCS3200 color sensor – shown in the figure below – uses a TAOS TCS3200 RGB
sensor chip to detect color. It also contains four white LEDs that light up the object in
front of it.
Specifications
Power: 2.7V to 5.5V
Size: 28.4 x 28.4mm (1.12 x 1.12″)
Interface: digital TTL
High-resolution conversion of light intensity to frequency
Programmable color and full-scale output frequency
Communicates directly to microcontroller
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Where to buy?
Click the link below to compare the sensor at different stores and find the best price:
Color Sensor TCS3200
How does the TCS3200 sensor work?
The TCS3200 has an array of photodiodes with 4 different filters. A photodiode is
simply a semiconductor device that converts light into current. The sensor has:
16 photodiodes with red filter – sensitive to red wavelength
16 photodiodes with green filter – sensitive to green wavelength
16 photodiodes with blue filter – sensitive to blue wavelength
16 photodiodes without filter
If you take a closer look at the TCS3200 chip you can see the different filters.
By selectively choosing the photodiode filter’s readings, you’re able to detect the
intensity of the different colors. The sensor has a current-to-frequency converter that
converts the photodiodes’ readings into a square wave with a frequency that is
proportional to the light intensity of the chosen color. This frequency is then, read by
the Arduino – this is shown in the figure below.
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Pin wiring
Here’s the sensor pinout:
Sensor Pin
I/O
Description
GND (4)
Power supply ground
OE (3)
I
Enable for output frequency (active low)
OUT (6)
O
Output frequency
S0, S1（1，2）
I
Output frequency scaling selection inputs
S2, S3（7，8）
I
Photodiode type selection inputs
VDD（5）
Voltage supply
Filter selection
To select the color read by the photodiode, you use the control pins S2 and S3. As
the photodiodes are connected in parallel, setting the S2 and S3 LOW and HIGH in
different combinations allows you to select different photodiodes. Look at the table
below:
Photodiode type
S2
S3
Red
LOW
LOW
Blue
LOW
HIGH
No filter (clear)
HIGH
LOW
Green
HIGH
HIGH
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Frequency scaling
Pins S0 and S1 are used for scaling the output frequency. It can be scaled to the
following preset values: 100%, 20% or 2%. Scaling the output frequency is useful to
optimize the sensor readings for various frequency counters or microcontrollers. Use
the table below:
Output frequency scaling
S0
S1
Power down
L
L
2%
L
H
20%
H
L
100%
H
H
For the Arduino, it is common to use a frequency scaling of 20%. So, you set the S0
pin to HIGH and the S1 pin to LOW.
Color Sensing with Arduino and TCSP3200
In this example you’re going to detect colors with the Arduino and the TCSP3200 color
sensor. This sensor is not very accurate but works fine for detecting colors in simple
projects. For this example, you’ll need the following parts:
Figure
Name
Arduino UNO
TCS3200 Color Sensor
Jumper Wires
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Schematic
Wiring the TCSP3200 sensor to your Arduino is straightforward. Simply follow the
next schematic diagram.
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Pin wiring
Here’s the connections between the TCSP3200 and the Arduino:
Sensor Pin
Wiring to Arduino Uno
S0
Digital pin 4
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S1
Digital pin 5
VCC
5V
S3
Digital pin 6
S4
Digital pin 7
OUT
Digital pin 8
Code
You need two sketches for this project:
1. Reading and displaying the output frequency on the serial monitor. In this
part you need to write down the frequency values when you place different
colors in front of the sensor.
2. Distinguish between different colors. In this section you’ll insert the
frequency values picked previously on your code, so that your sensor can
distinguish between different colors. We’ll detect red, green and blue colors.
1. Reading the output frequency
Upload the following code to your Arduino board.
/*********
Rui Santos
Complete project details at http://randomnerdtutorials.com
*********/
// TCS230 or TCS3200 pins wiring to Arduino
#define S0 4
#define S1 5
#define S2 6
#define S3 7
#define sensorOut 8
// Stores frequency read by the photodiodes
int redFrequency = 0;
int greenFrequency = 0;
int blueFrequency = 0;
void setup() {
// Setting the outputs
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pinMode(S0, OUTPUT);
pinMode(S1, OUTPUT);
pinMode(S2, OUTPUT);
pinMode(S3, OUTPUT);
// Setting the sensorOut as an input
pinMode(sensorOut, INPUT);
// Setting frequency scaling to 20%
digitalWrite(S0,HIGH);
digitalWrite(S1,LOW);
// Begins serial communication
Serial.begin(9600);
}
void loop() {
// Setting RED (R) filtered photodiodes to be read
digitalWrite(S2,LOW);
digitalWrite(S3,LOW);
// Reading the output frequency
redFrequency = pulseIn(sensorOut, LOW);
// Printing the RED (R) value
Serial.print("R = ");
Serial.print(redFrequency);
delay(100);
// Setting GREEN (G) filtered photodiodes to be read
digitalWrite(S2,HIGH);
digitalWrite(S3,HIGH);
// Reading the output frequency
greenFrequency = pulseIn(sensorOut, LOW);
// Printing the GREEN (G) value
Serial.print(" G = ");
Serial.print(greenFrequency);
delay(100);
// Setting BLUE (B) filtered photodiodes to be read
digitalWrite(S2,LOW);
digitalWrite(S3,HIGH);
// Reading the output frequency
blueFrequency = pulseIn(sensorOut, LOW);
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// Printing the BLUE (B) value
Serial.print(" B = ");
Serial.println(blueFrequency);
delay(100);
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/color/Color_Sensor_TCS230_TCS3200_1.ino
Open the serial monitor at a baud rate of 9600.
Place a blue object in front of the sensor at different distances. You should save two
measurements: when the object is placed far from the sensor and when the object
is close to it.
Check the values displayed on the serial monitor. The blue frequency (B) should be
the lowest compared to the red (R) and green (G) frequency readings – see figure
below.
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When we place the blue object in front of the sensor, the blue frequency (B) values
oscillate between 59 and 223 (see highlighted values).
Note: you can’t use these frequency values (59 and 223) in your code, you should
measure the colors for your specific object with your own color sensor. Then, save
your upper and bottom frequency limits for the blue color, because you’ll need them
later.
Repeat this process with a green and red objects and write down the upper and
bottom frequency limits for each color.
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2. Distinguish between different colors
This next sketch maps the frequency values to RGB values (that are between 0 and
255).
In the previous step the maximum frequency for blue as 233 and the minimum was
59. So, 59 in frequency corresponds to 255 (in RGB) and 223 in frequency to 0 (in
RGB). We’ll do this with the Arduino map() function. In the map() function you need
to replace XX parameters with your own values.
/*********
Rui Santos
Complete project details at http://randomnerdtutorials.com
*********/
// TCS230 or TCS3200 pins wiring to Arduino
#define S0 4
#define S1 5
#define S2 6
#define S3 7
#define sensorOut 8
// Stores frequency read by the photodiodes
int redFrequency = 0;
int greenFrequency = 0;
int blueFrequency = 0;
// Stores the red. green and blue colors
int redColor = 0;
int greenColor = 0;
int blueColor = 0;
void setup() {
// Setting the outputs
pinMode(S0, OUTPUT);
pinMode(S1, OUTPUT);
pinMode(S2, OUTPUT);
pinMode(S3, OUTPUT);
// Setting the sensorOut as an input
pinMode(sensorOut, INPUT);
// Setting frequency scaling to 20%
digitalWrite(S0,HIGH);
digitalWrite(S1,LOW);
// Begins serial communication
Serial.begin(9600);
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}
void loop() {
// Setting RED (R) filtered photodiodes to be read
digitalWrite(S2,LOW);
digitalWrite(S3,LOW);
// Reading the output frequency
redFrequency = pulseIn(sensorOut, LOW);
// Remaping the value of the RED (R) frequency from 0 to 255
// You must replace with your own values. Here's an example:
// redColor = map(redFrequency, 70, 120, 255,0);
redColor = map(redFrequency, XX, XX, 255,0);
// Printing the RED (R) value
Serial.print("R = ");
Serial.print(redColor);
delay(100);
// Setting GREEN (G) filtered photodiodes to be read
digitalWrite(S2,HIGH);
digitalWrite(S3,HIGH);
// Reading the output frequency
greenFrequency = pulseIn(sensorOut, LOW);
// Remaping the value of the GREEN (G) frequency from 0 to 255
// You must replace with your own values. Here's an example:
// greenColor = map(greenFrequency, 100, 199, 255, 0);
greenColor = map(greenFrequency, XX, XX, 255, 0);
// Printing the GREEN (G) value
Serial.print(" G = ");
Serial.print(greenColor);
delay(100);
// Setting BLUE (B) filtered photodiodes to be read
digitalWrite(S2,LOW);
digitalWrite(S3,HIGH);
// Reading the output frequency
blueFrequency = pulseIn(sensorOut, LOW);
// Remaping the value of the BLUE (B) frequency from 0 to 255
// You must replace with your own values. Here's an example:
// blueColor = map(blueFrequency, 38, 84, 255, 0);
blueColor = map(blueFrequency, XX, XX, 255, 0);
// Printing the BLUE (B) value
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Serial.print(" B = ");
Serial.print(blueColor);
delay(100);
// Checks the current detected color and prints
// a message in the serial monitor
if(redColor > greenColor && redColor > blueColor){
Serial.println(" - RED detected!");
}
if(greenColor > redColor && greenColor > blueColor){
Serial.println(" - GREEN detected!");
}
if(blueColor > redColor && blueColor > greenColor){
Serial.println(" - BLUE detected!");
}
}
SOURCE CODE
https://github.com/RuiSantosdotme/Random-NerdTutorials/blob/master/Projects/color/Color_Sensor_TCS230_TCS3200_2.ino
To distinguish between different colors we have three conditions:
When the R is the maximum value (in RGB parameters) we know we have a
red object
When G is the maximum value, we know we have a green object
When B is the maximum value, we know we have a blue object
Now, place something in front of the sensor. It should print in your serial monitor the
color detected: red, green or blue. Your sensor can also detect other colors with
more if statements.
Wrapping up
In this post you’ve learned how to detect colors with the TCSP3200 color sensor. You
can easily build a color sorting machine by simply adding a servo motor.
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Good luck with all your projects,
-Rui Santos
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