Adcon Telemetry A733 Remote Telemetry Unit User Manual A733SpecsTUV

Adcon Telemetry Inc Remote Telemetry Unit A733SpecsTUV

Revised technical manual and photos with schematics and bill of materials removed

ADCONTELEMETRY SMART WIRELESS SOLUTIONS A733 RTU Technical Reference (Type Approval)
ADCONTELEMETRYADCON TELEMETRY AGINKUSTRASSE 24A-3400 KLOSTERNEUBURGAUSTRIATEL: +43 (2243) 38 280-0FAX: +43 (2243) 38 280-6http://www.adcon.atADCON TELEMETRY INC1001 YAMATO ROAD SUITE #305, BOCA RATONFL 33431 USATEL: +1 (561) 989-5309FAX: +1 (561) 989-5310http://www.adcon.comADCON TELEMETRY SRLBD. ION IONESCU DELABRAD 8R-71592 BUCHARESTROMANIATEL: +40 (1) 490-6083FAX: +40 (1) 490-6086http://www.adcon.ro Proprietary Notice: The Adcon logo, the A730 series, A720 series and addIT™, A733 series andaddWAVE, addVANTAGE and AgroExpert™ are trademarks or registeredtrademarks of Adcon Telemetry AG. All other registered names used through-out this publication are trademarks of their respective owners.This publication contains confidential information, property of Adcon Teleme-try AG. Disclosure to third parties of the information contained herein is pro-hibited. Neither the whole nor any part of the information contained in thispublication may be reproduced in any material form except with the prior writ-ten permission of Adcon Telemetry AG.Release 1.0, December 14, 1999Copyright ©1999 by Adcon Telemetry AG.All rights reserved.
3 Table of Contents Introduction ____________________________________________________7 About the A733 ______________________________________________________________ 7 Hardware _______________________________________________________9 Overview_____________________________________________________________________ 9 The Modem Interface _________________________________________________________________ 10The Microcontroller and the Power Management Sections _________________________________ 10The Analog + Digital I/O Interface Board ________________________________________________ 13The Power Supply and the Serial Interface _______________________________________________ 13External Power Supply_________________________________________________________________ 14 Specifications________________________________________________________________15PCB Parts Placement (A733) __________________________________________________16Bills of Materials _____________________________________________________________17 A733MB _____________________________________________________________________________ 17A733CA _____________________________________________________________________________ 19 A733 Device’s Photographs___________________________________________________20 The A431 Radio Module _______________________________________ 25 About the A431 Radio Module________________________________________________25Functional description________________________________________________________25 Receiver Section ______________________________________________________________________ 25Transmitter Section____________________________________________________________________ 26
4 Manufacturing Issues ________________________________________________________ 28 Marking and labeling issues ____________________________________________________________ 28Alignment Range and Switching Range __________________________________________________ 28Tuning Procedure _____________________________________________________________________ 29Setting Up the Default Parameters ______________________________________________________ 29Commands valid for all bands ____________________________________________________ 30Commands required for band 1 __________________________________________________ 30Commands required for band 2 __________________________________________________ 30Commands required for band 3 __________________________________________________ 30Commands required for band 4 __________________________________________________ 30Definitions ___________________________________________________________________________ 31Test Equipment Settings _______________________________________________________________ 32Network Analyzer (HP 8712 or equivalent)_____________________________________________ 32Service Monitor (Rohde & Schwarz CMS50 or equivalent) _______________________________ 32Trimming Elements____________________________________________________________________ 33Adjusting the Receiver Front End _______________________________________________________ 33Adjusting the VCOs ___________________________________________________________________ 34Adjusting the Crystal Reference _________________________________________________________ 35Checking the Receiver Parameters ______________________________________________________ 35Checking the Transmitter Parameters ____________________________________________________ 35Data Transfer Check ___________________________________________________________________ 36 PCB Parts Placement_________________________________________________________ 37Bill of Materials (A431) _______________________________________________________ 38Frequency Reference Specifications ___________________________________________ 42A431 Module’s Photographs _________________________________________________ 43 Software ______________________________________________________45 Short Description____________________________________________________________ 45Tasks _______________________________________________________________________ 45Controlling the Unit__________________________________________________________ 47 Serial Communication Protocol _________________________________________________________ 47General Format of a Command _________________________________________________________ 47General Format of an Answer___________________________________________________________ 48Commands___________________________________________________________________________ 48 CMDS _____________________________________________________ 48TIME _____________________________________________________ 49 BL ____________________________________________________________________________ 49FREQ _________________________________________________________________________ 49DATA _________________________________________________________________________ 50IMME _________________________________________________________________________ 52
5 INFO _________________________________________________________________________ 52RX ___________________________________________________________________________ 53TX ___________________________________________________________________________ 54B ____________________________________________________________________________ 54Returned errors list____________________________________________________________________ 54Command line interpreter _______________________________________________________ 54Device descriptors and storage handler ___________________________________________ 55Real time clock ________________________________________________________________ 55Radio interface ________________________________________________________________ 55Notifications __________________________________________________________________ 55 Adcon Packet Radio Protocol _________________________________________________56 Digital Squelch _______________________________________________________________________ 56Modulation Technique Used____________________________________________________________ 57Generic Format of a Radio Frame _______________________________________________________ 57Data Frames _________________________________________________________________________ 59Frame Types _________________________________________________________________________ 59Request ______________________________________________________________________ 59Broadcast Answer ______________________________________________________________ 60Broadcast Request _____________________________________________________________ 60Ping __________________________________________________________________________ 61Pong _________________________________________________________________________ 61Fdev _________________________________________________________________________ 62Data12 _______________________________________________________________________ 62Set ID ________________________________________________________________________ 63Set Slot Time and Sample Rate __________________________________________________ 64Set Frequency _________________________________________________________________ 64Set Battery Charge Levels _______________________________________________________ 65General Acknowledge __________________________________________________________ 65
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7 1. Introduction 1.1. About the A733 The A733 Remote Telemetry Unit (RTU) is a portable low-power, medium-range te-lemetry device capable of sampling up to 12 analog and 8 digital inputs (of which 4are counter types); in addition, it can control up to 4 outputs. A 3-volt CMOS serialinterface is also built-in, allowing for configuration, data download, or expansion(e.g. various bus implementations). The unit is based on a powerful 8-bit Flash RISCmicrocontroller, which can also be programmed in the field (for software upgrades).The units incorporates an A431 radio module operating in the 430 to 470 MHzrange, making it adaptable to most radio communication regulations in the world.The output power is 0.5 W, while the modulation is narrow band FM (12.5, 20 or 25kHz channel spacing).Due to its construction, as well as to the software controlling it, the power consump-tion is extremely low (average 1 mA—without sensors). The unit operates from abuilt-in NiCd 6.2 Volt rechargeable battery, which is charged using either a solarpanel or an external power supply adapter. A special configuration may be imple-mented where no internal battery is used, rather the power is obtained exclusivelyover an external connector.The A733 is a ruggedized unit, complying with the IP65 environmental protectionclass (NEMA 4). It can be easily installed and it integrates perfectly with an AdconA730 network.This manual describes the technical details of the A733, both hardware and soft-ware. It is organized in several parts, as follows:
8Introduction • Hardware: includes the schematics as well as a description of the main boardand interface boards of the A733• The A431 radio module: includes the schematics and description of the radiomodule• Software: a short description of the software with the most important com-mands that can be used to control the unit over the serial interfaceThis manual is intended for the radio approval authorities and laboratories.
9 2. Hardware 2.1. Overview Most of the electronics (including the A431 radio module) are situated on the mainboard (for the A431 description, see “The A431 Radio Module” on page 25). Themain board (Figure 1) contains the radio unit, a low-speed modem interface, a mi-crocontroller and a power management subsystem. For the analog inputs and thedigital inputs/outputs, two identical interface boards (A733CA) holding the 7-pinBinder connectors are used. The serial line and the power are provided on a 5-pinBinder connector, while the antenna is fed through a 50 Ω BNC connector. Figure 1. A733 Block Diagram.A431 RadioAntennaµControllerModemInterfacePowerManagementSystem SupplyBatteryExternal PowerADC128Analog InputsDigital I/O3 V CMOS Interface ModuleSerial
10Hardware For further details, consult the schematic diagram in Figure 2. 2.1.1. The Modem Interface The modem operates with two tones: 1 kHz (representing the “1” bits) and 2 kHz(representing the “0” bits). A bit cell is represented by a complete time period ( 1/f ),thus the raw throughput varies between 1 and 2 kbps (average 1.5 kbps). The mo-dem functions are essentially implemented in software. However, a signal condition-ing is performed on both receive and transmit paths.On receive, the buffered analog data signal from the radio unit is applied to a 3 kHzlow pass filter (U6). The filter output is further fed both to a Schmidt trigger (U5:A)and a 100 Hz low-pass filter (U5:B), the output of the latter being used as a referencefor the slicer (the Schmidt trigger). The TTL data, RXDO , is obtained at the outputof the slicer (i.e. on TP1). The microcontroller overtakes the decoding operation (seealso “Modulation Technique Used” on page 57).On transmit, a two-poles low-pass filter (U11) is used: its role is to “smooth” thesquare signal TXDI generated by the microcontroller. Before entering the filter, a microprocessor-controlled, variable-gain amplifier built with U12/U13 is used to setthe modulation level for different bandwidths (12.5, 20 or 25 kHz). The selected val-ue is stored in the microcontroller’s EEPROM during the aligning procedure. 2.1.2. The Microcontroller and the Power Management Sections The operation of the whole unit is under the control of U9, an Atmel ATMega 103microcontroller. It is a powerful chip exhibiting a very low power consumption. Itsmain functions are:• Controls the radio unit• Implements the modem functionality• Assembles the radio frames and waits for requests from a remote• Performs the sampling of the sensor inputs and the A/D conversion• Stores the values in a local FIFO; manages the FIFO• Implements the pulse counter function• Manages the real-time clock• Assures the power management• Implements a serial Command Line Interface (CLI)The chip operates at its maximum speed, in this case 4 MHz (the “L” version), anduses a crystal (X2) for the on-board clock generator. The real time clock is imple-mented by means of a 32.768 kHz crystal (X1) connected on the internal Timer/Counter0.
11The Microcontroller and the Power Management Sections The radio unit is controlled via the SPI bus (to set the PLL chip parameters) and viaseveral ports of the microcontroller for such operations as transmit and receive. Inaddition, the high current 5 volt LDO voltage source (U4) is switched on before theradio module’s PA must be activated.The modem’s output (implemented in soft-ware) is available on PB5 ( TXDI ), while the receiver output is fed to PD4 ( RXDO ).The A/D subsystem is used to sample the inputs (ADC0 to ADC5); the 6th and 7thanalog input are used for on-board measurements as local battery, internal temper-ature and RSSI/PO signal; the battery and temperature voltages are switched bymeans of the analog switch U19. A stable 2.5 Volt reference supplied by U8 is ap-plied to the A ref pin. The reference is powered by the microcontroller only whensampling the A/D inputs. The external sensors are powered through U17. In orderto enlarge the maximum number of sensors sampled, several analog multiplexersare used (U3/U7/U10). After sampling the A/D once, the software switches the mul-tiplexers (using the signal MUX , pin PD2) and samples the inputs once again, thusdoubling to 12 the maximum number of analog inputs.The sampled input values are stored in a FIFO memory based on a serial EEPROMchip, U18. These values may be retrieved when a request is received over radio, orover the serial line. The configuration parameters (e.g. the serial number of the de-vice, the operating frequency, etc.) are stored in the microcontroller’s on-chip EE-PROM.The pulse counter functionality is implemented by means of the four interrupt inputsINT4 to INT7 of the ATMega 103 microcontroller.The power management supervises the charge/discharge of the battery (via Q1 andhalf of U15), senses when it reaches the “misery” state and switches off the unit inorder to protect the battery (second half of U15). In addition, the software senses theunit’s idle state (e.g. the unit is in a warehouse in storage condition), where no activ-ities must be performed thus driving the unit into hibernation. If the unit is switchedoff due to an extremely low battery level, Q2 would start it up again only if externalpower is applied to the power connector (e.g. from a solar panel).The terminal mode is implemented by means of the built-in UART. No on-board lev-el drivers are present in order to minimize power consumption; a special adapter ca-ble that performs the CMOS to RS232 level shift is available. By means of this cableand using the implemented commands, various parameters can be changed/config-ured.A brown-out supervisor chip (U14) is used to assure a smooth start-up of the micro-controller and avoid possible erratic behavior when the battery level descends be-low the minimum operating value (2.7 volts). The same chip activates the write-protect signal of the serial EEPROM during reset, in order to protect the data in theEEPROM.
13The Analog + Digital I/O Interface Board 2.1.3. The Analog + Digital I/O Interface Board The two identical interface boards ensure the connection between the main boardand the outside world (see Figure 3). The interface boards contain two connectorseach ( I/O A and I/O B or I/O C and I/O D respectively) and some active/passivecomponents protecting the inputs. Each of the I/O connectors can accept:• Three analog inputs• One digital Input or Output (its function can be switched under program con-trol, also remotely)• One pulse counter inputDepending on the way R3 and R4 are populated, the power supply to the I/O de-vices can be either switched or permanent. This option is factory programmableonly. If R3 is populated, the power will be permanently applied to the sensors whileif R4 is populated, the power will be applied for a defined time (typically 2 seconds)only shortly before the microcontroller samples the inputs. 2.1.4. The Power Supply and the Serial Interface The POWER connector allows for:• External supply (battery or any DC source from5.6 to 10 volts)• External charge supply (either a solar panel oran AC adapter) if an internal rechargeable bat-tery is used• Communication over serial lines, at 19200 baud Note: The serial line is 3 volt CMOS compatible, therefore a special adapter cable must be used to reach the RS-232 levels. Also, if an external battery is used, the internal battery must be disconnected.RxDTxDGroundBatteryExt Power12345
15External Power Supply when the battery voltage drops below 5.6 Volts, and under 5.9 Volts the RF opera-tion may stop. Figure 4. Connection of an external power supply. 2.2. Specifications The A733 fulfills the specifications of the EN 300 220-1, Class 12, ETS 300 086 andETS 300 113, as well as the FCC Part 90.214 (Subpart J) of the CFR 47. Note: The parameters below were measured with the A733 + A431 combination. Parameter Min Typ Max Unit CommonSupply 5.6 6.2 10.0 VOperating Temperature -30 +70 °CRelative Humidity 99 %Class Protection IP65Data Rate (Using the On-board Software Modem) 1000 1500 a 2000 bpsOperating Frequency (-44 version) b 430 450 MHzOperating Frequency (-46 version) b 450 470 MHzFrequency Stability (-20 to +50°C) ±1.5 kHzFrequency Stability (-30 to +60°C) ±2.5 kHzReceiverSensitivity (12 db S/S+N) -118 dBmImage Frequency Attenuation (1st IF = 45 MHz) -70 dBPOWERI/O CI/O D+-BlackRed5 to 10 VoltRS232++Power Cable Serial Adapter CableI/O AI/O BANT
16Hardware 2.3. PCB Parts Placement (A733) Figure 5. A733MB Parts placement (top). Local Oscillator Leakage 2 nWAdjacent Channel Attenuation -70 dBRSSI dynamic 90 dBOperating Current (incl. On-board Microcontroller) 25 mATransmitter (all measurements made on a 50 Ω resistive load)Output Power 27 dBmSpurious Radiation 200 nWAdjacent Channel Power (12.5 kHz version) -34 dBmAdjacent Channel Power (25 kHz version) -44 dBmOccupied Bandwidth (12.5 kHz version) 7.0 kHzOccupied Bandwidth (25 kHz version) 12 kHzOperating Current (incl. On-board Microcontroller) 600 mA a. Data rate is content dependent.b. This parameter represents the alignment range; the switching range canbe limited in the software to a narrower space (even to the extent of asingle channel). Parameter Min Typ Max Unit
21A733CA Figure 9. A733, Back view. Figure 10. A733, Top view.
22Hardware Figure 11. A733, Bottom view. Figure 12. A733, Left view.
23A733CA Figure 13. A733, Right view. Figure 14. A733, Case opened.
24Hardware Figure 15. A733 Motherboard, top view. Figure 16. A733 Motherboard, bottom view.
25 3. The A431 Radio Module 3.1. About the A431 Radio Module The A431 was specially designed for narrow-band FM data communication. It exhib-its a relatively flat response in the audio band from 10 Hz to 2.5 kHz, both on sendas well as on receive paths. Additionally, the receiver’s group delay is very low.The module operates in the 430 to 470 MHz range, making it compatible with mostradio communication regulations in the world. The output power is 0.5 W, while themodulation is narrow-band FM (12.5, 20 or 25 kHz channel spacing). The power con-sumption in receive mode is remarkably low (under 25 mA), in spite of the excellentIP3 characteristics and high sensitivity. The switching from receive to transmit is fast,under 20 mS. 3.2. Functional descriptionThe following functional description refers to the schematic diagram in Figure 17.3.2.1. Receiver SectionThe antenna signal is fed through the common low-pass filter for both receive andtransmit and applied to the U3 antenna switch. From the J3 port of the switch, it isthen fed to the FL1 helical filter and amplified by the LNA built with Q2 that assuresa high amplification factor (over 20 dB). Another helical filter follows (FL2), giving atotal of more than 70 dB attenuation of the first image frequency.
26The A431 Radio ModuleThe incoming signal is then applied to the first mixer, U7, through an LC impedancematching network (L12/C48). The local oscillator signal is obtained by means of theVCO built around U10 and applied to the mixer. The VCO is locked to the OSC1 ref-erence by means of the U9 dual-PLL chip.The mixer’s output on 45 MHz is filtered by means of XF1, which is needed to ensurea sufficient attenuation (over 70dB) of the second image frequency (at 44.090 MHz).The signal is pre-amplified with Q6 before entering the U8 mixer/IF chip. The sec-ond local oscillator is built around the IF chip, but it is locked by means of the secondPLL of U9. In this way, all signals are generated from a common reference oscillator(OSC1, see also “Frequency Reference Specifications” on page 42).The IF chain chip amplifies the signal to a proper level for FM detection. A particu-larity of this chip is that the FM detector is PLL-based, thus no coils or ceramic dis-criminators are needed. Two ceramic filters, CF1 and CF2, ensure the requiredadjacent channel separation. The audio output is delivered on pin 17 and is slightlyamplified through U11 in order to bring it to 1Vpp, and centered on half the supplyvoltage (which is 3.3 volt approximately). The signal is inverted in order to compen-sate the inversion caused by the first mixer (the LO is higher than the received RFsignal). The audio signal is fed out of the module on the pin RXDO of the interfaceconnector. In addition, an RSSI level signal is obtained on pin 18 of U8 and is fed toswitch U6. As long as the module is in receive mode, the RSSI signal will be presenton the RSSI/PO pin of the interface connector.3.2.2. Transmitter SectionThe carrier is generated directly on the operating frequency by means of the VCObuilt around U2. The signal is locked on the reference OSC1 with the aid of the dualPLL chip based on U9. The chip, a National Semiconductor LMX2332L, was chosenfor its fast locking scheme, low power consumption, and good RF characteristics.The modulation is applied on both the VCO and the reference, in order to attain aflat characteristic in the whole band (10 Hz to 2.5 kHz). Due to the phase differencesbetween the two modulation points, the signal applied on the reference is invertedby means of U4. Meanwhile, U4 is used to center the reference on the channel (usingthe trimpot R75). The PLL low-pass filter (third-order) composed of C66/C67/R69/R59/C64 is calculated around 800 Hz. R64 is used for the FastLock® mechanism.(For further details on the FastLock mechanism, please consult the National Semi-conductor documentation.)The signal is pre-amplified to approximately 0 dBm by Q1 and then it is applied tothe PA built with U1. The output signal is pre-filtered and impedance-matched bymeans of theC21/L10/C22 low-pass filter and then fed to the antenna switch. Beforereaching the antenna output, a three-cell, low-pass filter (used also on the receivepath) is used to attenuate the unwanted harmonics and keep them below the re-quired limits.
28The A431 Radio ModuleAn Automatic Level Control (ALC) system is responsible for keeping the output pow-er constant, regardless of the external influences (temperature, VCO excitation and/or supply). A small part of the RF energy is rectified by D2 and applied to the U5:Aamplifier. By means of U5:B, the power is controlled according to the pre-set powerlevel (ALC input). U5:A is basically an analog comparator between the actual and theprogrammed power output. Depending on the error signal obtained, a variable volt-age is applied on the PD input of the PA chip, thus effectively controlling its outputpower. In addition, the actual power output level is fed to the U6 analog switch andpresented to the RSSI/PO output while the unit is switched in transmit mode.The modulation is applied on two-points: the VCO and the reference oscillator—thisis needed to obtain a flat response in the audio range from 10Hz to 2.5 kHz and com-pensate for the counter-effect opposed by the synthesizer loop. The input signal(must be 1 Vpp) is fed through a resistive divider (R14/R13) to the “cold” end of thevaractor diode controlling the VCO (D1). At the same time, the same modulationsignal is applied to the inverting op-amp U4 and then to the OSC1 reference oscil-lator (a VCTCXO). The modulation signal is inverted in order to bring it in phase withthe VCO modulation point.3.3. Manufacturing Issues3.3.1. Marking and labeling issuesThe A431 Module is manufactured in two versions:• Low band—able to operate between 430 and 450 MHz• High band—able to operate between 450 and 470 MHzFrom a manufacturing perspective, the difference between the high and low bandare the two helical filters FL1 and FL2 used on the receiving chain. The low band ver-sion is marked as A733-44 while the high band is marked as A733-46.3.3.2. Alignment Range and Switching RangeThe A431 radio module’s alignment range is 20 MHz, while the switching range is10 MHz. According to the definitions formulated in the ETS 300086 and ETS 300013specifications, the A431 radio module belongs to the AR1 category. Therefore, forthe European testing, two units should be presented for test purposes, as follows:• One A733 unit containing an A431-44 radio module, alignment range 430-450 MHz, switching range 435-455 MHz• One A733 unit containing an A431-46 radio module, alignment range 450-470 MHz, switching range 455-465 MHz.Consequently, two test reports will be provided to Adcon Telemetry AG.
29Tuning ProcedureFor North America (FCC), only the portion 460 to 470 MHz will be used; therefore,a single device model A733-46 having the switching range between 460 and 470MHz will be submitted for testing.3.3.3. Tuning ProcedureThe A431 modules are to be tuned by mounting them on a test fixture consisting ofa specially modified A733 motherboard. The modification refers to certain mechan-ical aspects, in order to provide an easy plug in and out of the control connector (P2)as well as to the TP1 and TP2 test points.The alignment operation must differentiate between following classes of units:• Band 1: from 430 to 440 MHz• Band 2: from 440 to 450 MHz• Band 3: from 450 to 460 MHz• Band 4: from 460 to 470 MHzNote: The boards differ only through the FL1 and FL2, in that Band 1 and 2 use models TOKO 493S-1071A and 492S-1056A while Band 3 and 4 use models TOKO 493S-1075A and 492S-1060A, respectively. In addition, the tuning pro-cedure and some software parameters differ. The differences are clearly stat-ed in the following paragraphs, where applicable.3.3.4. Setting Up the Default ParametersThe tuning procedure is not possible without first configuring some default param-eters for the A733 motherboard used in the testing fixture. This is done via the serialinterface of the motherboard by using a communication terminal program (e.g. Hy-perterminal, in Microsoft® Windows™ 95). The terminal program must be config-ured as follows:• 19200 Baud• 1 Stop bit• No parity• No protocol (neither hardware, nor software)To check if the communication is operational, press theENTER key. Annnnn 0 # prompt should appear on the terminal screen (nnnn is the actual ID of the unit thatis printed on its label). The following default parameters must be pre-loaded (formore information about the meaning of the commands, consult the section “Com-mands” on page 48):RxDTxDGroundBatteryExt Power12345
30The A431 Radio ModuleCommands valid for all bandsID 1PMP 65 72SLOT 900 15RSSI 58Commands required for band 1TF 430000000BL 430000000 440000000FREQ 430000000 12500Commands required for band 2TF 440000000BL 440000000 450000000FREQ 440000000 12500Commands required for band 3TF 450000000BL 450000000 460000000FREQ 450000000 12500Commands required for band 4TF 460000000BL 460000000 470000000FREQ 460000000 12500Note: The TF command sets the start tuning frequency, the BL command sets the band limits, and the FREQ command sets the actual operating frequency; before shipping and depending on the target country, the last two parame-ters may be changed. The BL command must always be issued before the FREQ command.
31Definitions3.3.5. DefinitionsThe diagram of the setup environment is depicted in Figure 18.Figure 18. Trimming Setup.The testing fixture is used to fasten the A431 Module under test both mechanicallyand electrically in such a way as to allow its rapid and comfortable alignment. It con-sists of a mechanical board with two screws that are used to fasten the board; twoelastic pins are used to transport the relevant signals from the module to their cor-responding test cables. The external coaxial switch or relay (Power/Sens. <–> Wob-ble) allows switching of the antenna input/output to the network analyzer or to theservice monitor. The schematic diagram of the testing fixture is depicted inFigure 19.Figure 19. Schematic Diagram of the Testing Fixture.0.765 VPower/Sens WobbleOutScope Ant I/O OutVoltmeter OutNetworkAnalyzerTestingFixtureRS232 To/From PC+–6.5 VA733MBConnectorOptionalScope Service Monitor Network Analyzer VoltmeterScopeOut NetworkAnalyzerAntGndTP1A733MBTP2TP2 Voltmeter470KΩAntennaA431Module
32The A431 Radio Module3.3.6. Test Equipment SettingsBefore proceeding, certain controls on the test equipment must be set; some of thesettings depend of the operating band (high or low) of the device under test (DUT).In addition, it is highly recommended that the ambient temperature during align-ment is kept to 24° C (±2°C).3.3.6.1. Network Analyzer (HP 8712 or equivalent)The settings for the Network Analyzer are as follows:• Center frequency: 450 MHz• Span: 100 MHz• Display: 10.0 dB/div• Power: -20 dBm• Markers: — band 1: Mkr1 – 435 MHz, Mkr2 – 430 MHz, Mkr3 – 440 MHz— band 2: Mkr1 – 445 MHz, Mkr2 – 440 MHz, Mkr3 – 450 MHz— band 3: Mkr1 – 455 MHz, Mkr2 – 450 MHz, Mkr3 – 460 MHz— band 4: Mkr1 – 465 MHz, Mkr2 – 460 MHz, Mkr3 – 470 MHzNote: It is a good idea to store the instrument state for the four settings for a rapid recall when needed.3.3.6.2. Service Monitor (Rohde & Schwarz CMS50 or equivalent)The setting for the receiver section check are as follows (RX-TEST):• SET RF: 430000000 Hz (Band 1) / 440000000 Hz (Band 2) / 450000000 Hz(Band 3) / 460000000 Hz (Band 4)• RF LEV: 1 µV• SINAD• AF1: 1kHz• MOD1: 2.5 kHz• SCOPE MODE• BEST RANGEThe settings for the transmitter section check (TX-TEST):• COUNT: (should show the transmitter carrier frequency)• POWER: (should show the transmitter carrier power)
33Trimming Elements3.3.7. Trimming ElementsThe location of the trimming elements on the A431 Module is shown in Figure 20.Figure 20. Location of the trimming elements.3.3.8. Adjusting the Receiver Front End1. Mount the DUT (Device Under Test) on the testing fixture and connect it to the host via the serial cable.2. Select the appropriate instrument profile depending on the device’s band.3. Turn the DUT in permanent receive mode by entering the RX command at the terminal.4. Check that the switch on the Testing Fixture is in the Wobble position.5. Adjust the FL1 and FL2 filters (see Figure 20) until you obtain a curve similar to the one shown in Figure 21 (depending on the band, the markers may be different); this is done by successively adjusting the five trimming screws located on the filters.R75 (Crystal Reference)FL1FL2L15 (RX VCO)L7 (TX VCO)
34The A431 Radio ModuleIf the adjustments do not achieve the appropriate curve, check the power supply,the cable connections to/from the test equipment, etc. Verify also that all the pins ofthe FL1 and FL2 filters are properly soldered.Figure 21. Helical Filter + LNA’s selectivity diagram.3.3.9. Adjusting the VCOs1. Flip the switch on the Testing Fixture to the Power/Sens. position.2. Verify that the DUT is in receive mode (enter the RX command at the terminal program).3. Adjust the L15 coil (see Figure 20) until the voltage shown on the digital voltmeter is 900 mV, ±50 mV (see also the note below).4. Switch the unit to transmit mode by entering TX at the terminal.5. Adjust the L7 coil (see Figure 20) until the voltage shown on the voltmeter is again 900 mV, ±50 mV.6. Press the enter key at the terminal to switch the unit off.Note: A calibration may be needed due to the internal resistance of the voltmeter and the serial resistor mounted on the Testing Fixture. The calibration is per-formed by measuring the VCO voltage directly on the TP2 and by comparing the value with that measured through the Testing Fixture. The values given above are the real ones, measured directly.If the above limits cannot be obtained, or the readout is unstable, verify the follow-ing:• The programmed operating frequencies are indeed 430 (Band 1), 440(Band 2), 450 (Band 3) and 460 MHz (Band 4). To check this, type the com-mand FREQ at the terminal prompt; the device will answer by returning thecurrent frequency.• The respective commands (RX and TX) were issued.
35Adjusting the Crystal Reference• No parts are missing, or have the incorrect value, or are badly soldered (checkthe parts around U2 and U10).3.3.10. Adjusting the Crystal Reference1. Flip the switch on the Testing Fixture to the Power/Sens. position.2. Switch the unit to transmit mode by entering TX at the terminal.3. Observe the indication shown by the Service Monitor: adjust R75 (see Figure 20) until the carrier frequency indicates 430000000 (Band 1), 440000000 (Band 2), 450000000 (Band 3), or 460000000 MHz (Band 4) ± 200 Hz, respectively.3.3.11. Checking the Receiver Parameters1. Verify that the switch on the Testing Fixture is flipped to the Power/Sens. position.2. Switch the DUT to receive mode by entering RX at the terminal.3. Switch the Service Monitor to RX TEST mode, on the appropriate frequency (430 / 440 / 450 or 460 MHz respectively); the level should be 1 µV (see also “Test Equipment Settings” on page 32).4. Verify that the S/N ratio is at least 12 dB; in addition, if a scope is also connected, a clear 1 kHz sine wave should be visible, with a relatively low amount of noise superimposed.5. Switch the DUT to pulsed mode by pressing the Enter key. After several seconds, you will see the image on the scope pulsing at about one-second intervals.6. Switch the RF generator output off.7. Verify that the RSSI threshold is correct by typing the command RSSI; the actual value must be lower than the threshold set. If this is not the case, repeat the RSSI command several times—perhaps the frequency is in use (a radio receiver set on the operating frequency would help detect foreign transmissions). If the threshold difference is marginal, it must be increased by using the RSSI <value> command (it must be 20 to 30% higher than the actual value).If any of the above targets are not reachable, visually verify first that the U8 chip iscorrectly soldered and that there are no shorts between its pins (most problems usu-ally appear around this chip).3.3.12. Checking the Transmitter Parameters1. Verify that the switch on the Testing Fixture is flipped to the Power/Sens. position.2. Switch the DUT to transmit mode by typing the command TX 0 at the terminal.
36The A431 Radio Module3. Switch the Service Monitor to TX TEST mode, on the appropriate frequency (430 / 440 / 450 or 460 MHz respectively). You should see the following parameters on the Service Monitor readout:a. Carrier: 430000000 ± 200 Hz (or 440000000 / 450000000 / 460000000 respectively)b. Output Power: 26.5 dBm (+ 0.5 dBm / - 1 dBm)c. Frequency Deviation: ±2.0 kHz (±0.2 kHz)4. Switch the unit to stand-by by pressing the Enter key.For item 3.a above, adjust R75 (see Figure 20). For item 3.b, issue the commandPWR at the terminal and use the D (down) and U (up) keys until the required valueis reached. Finally, for item 3.c, issue the command BW at the terminal and againuse the D and U keys to reach the required value.3.3.13. Data Transfer CheckThe last check is a radio data transfer. In order to perform it, at least a base station(model A730SD) or another remote station (model A733) must be installed and op-erated on the same test frequency, in the near vicinity (no more than 30 m).Note: The base or remote station used for this test must be operated with a fictive antenna (a 50Ω resistor).To perform the test, enter the command B at the terminal prompt: the base and/orremote station must answer with the RF in and out values. If an answer is not re-ceived after several seconds, retry the command. If an answer is still not received,then use a scope on TP1 on the A733MB board (the Text Fixture) to verify that thedigital data is present (on receive). In addition, a radio receiver tuned on the oper-ating frequency can also supply a rough indication of whether the receiver or thetransmitter is defective.
37Data Transfer Check3.4. PCB Parts PlacementFigure 22. A431 Parts placement (top).
42The A431 Radio Module3.6. Frequency Reference Specifications
43Data Transfer Check3.7. A431 Module’s PhotographsFigure 24. A431 Module, General view.Figure 25. A431 Module, Top view.
44The A431 Radio ModuleFigure 26. A431 Module, Bottom view.
454. Software4.1. Short DescriptionThe software is written entirely in C. It consists of a collection of standard C libraryfunctions, a pre-emptive multitasking operating system (CMX) offering basic config-uration and administration functions (including a command line terminal on a serialport), and the application software itself, which assures the desired functionality ofthe device.4.2. TasksFollowing tasks are currently implemented:• Command Line Interpreter Task• Radio Task• Memory Management Task• Real Time Clock (RTC) TaskThe system usually remains in sleep mode. Each 0.5 seconds, an interrupt is gener-ated by the local 32.76 Khz crystal oscillator. This wakes up the processor and acti-vates the CMX RTOS, which allows all active tasks to perform their functions. Afterall the tasks have finished their jobs, CMX brings the system back to sleep. The 0.5seconds interrupt routine is also used as time reference for the RTC task.In parallel to the normal, regular operation of the CMX, the system responds to thepulse counter interrupts (they are generated by four inputs on the microcontroller
46Softwareand are used for event counting, e.g. rain gauges). These interrupts are handled bya separate driver.One of the main concerns of the software design is the power consumption of thedevice. The software must ensure that all the peripherals are left in the correct statein order to reduce their consumption to a minimum; all operations are executed inthe shortest possible time.Figure 27. General flow chart of the A733 software.ResetInitializationSleep0.5 secinterrupt?NoYesConnectivityCheck? Do ConnectivityCheckYesTerminalMode?NoEnable TerminalModeYesNoRF ChannelActivity? Handle IncomingMessageYesNoTime to A/DSample?A/D Sampleand Process YesSwitch offEverythingBatteryLow? StorageMode? YesNo NoNoStopBatteryDistress?YesYesNo0.5 sec InterruptAdvance theRTC one secondReturnIncrementthe RTC?YesNoCounter InterruptDebounce inputReturnIncrementaffected Counter
47Serial Communication Protocol4.3. Controlling the UnitThe unit under test can be controlled by means of the special serial cable suppliedby Adcon Telemetry that is connected to a PC (e.g. a laptop) on one side and to thePOWER connector on the other side. In order to switch the unit to various modes ofoperations, a simple communications terminal program will suffice (e.g. Terminal orHyperterminal in Windows, or Kermit under other platforms). The terminal programmust be configured as follows:• 19200 Baud• 8 Data Bits• No Parity• 1 Stop Bit• Force LF after CRNote: The interface is TTL, not RS-232. The adapter cable provided by Adcon must be used.4.3.1. Serial Communication ProtocolThis protocol is based on a master sending commands and a node answering; thewhole communication is conducted in plain ASCII, as strings. When exchangingnumbers, they are represented in decimal format. All commands are terminated witha CR/LF combination. All responses (answers) are terminated with the # character.4.3.2. General Format of a CommandThe commands have the following format:ID Command Param1 Param2 ... ParamN•ID is the destination device. If you include an ID as part of a command, thenode checks whether ID=ownID. If it does, the node executes the commandon itself. If the ID is not the node’s ID, the node executes the command on aremote device, if such an ID exists. If the ID is missing, this implies that thecommand is addressed locally.Note: Not all the commands can be relayed remotely.•Command is the command proper, which can be composed of a variable stringof characters (for example, SLOT). Each node can implement a set of com-mands depending on the functionality of the node itself. However, as a mini-mum requirement, a node recognizes the CMDS command, which returns a listwith the commands recognized by the node.•Param1 Param2 ... ParamN represent the parameters, which are com-mand dependent. If you type no parameters when you issue a command, it isthe equivalent of querying for information (the GET version of a command). If
48Softwareyou type parameters, you are issuing the SET version of a command and aresetting the command to the parameters you typed.4.3.3. General Format of an AnswerThe answers have the following format:ID Command Result1 Result2 ... ResultN ErrResult #•ID is the answering device. If a command was further routed, it is the ID ofthe end device. The answer must always contain the ID on return.•Command is the string representing the original command. It is supplied sothat a master can distinguish between the answers it is waiting for, and out-of-band notifications (which may come, for example, over the radio port of anode). As with the ID, the command name must be always supplied.•Result1 Result2 ... ResultN are the result values returned by the re-mote node. If the ErrResult is not zero, all other possible characters and/or strings until the end of the line may be ignored.•ErrResult shows whether the command was successfully executed. If thisvalue is 0, the command was successfully executed. If this value is other than0, the command failed. The number may further indicate the error type. (Seealso “Returned errors list” on page 54.)The answer string may contain any number of spaces or CR/LF characters betweenits components; however, after the terminator (#) no other characters are allowed.4.3.4. CommandsBoth uppercase and lowercase characters can be typed because the commands arenot case sensitive. The commands list is not exhaustive, only those commandsdeemed necessary for type approval testing were included.CMDSDESCRIPTION Returns a list of supported commands.PARAMETERS None.REMARKS GET only.RETURNS A list of strings separated by spaces.REMOTE No.EXAMPLE CMDS193 CMDS CMDS ID PMP RSSI TIME FREQ DEV DEL REPL SLOT DATA INFO RX TX ERA 0#
49CommandsTIMEDESCRIPTION Sets/returns the real time clock.PARAMETERS The actual time, or none in the GET version.RETURNS The actual time as dd/mm/yyyy hh:mm:ss.REMARKS GET/SET.REMOTE No.EXAMPLES TIME 12/12/1999 22:10:10193 TIME 0#TIME193 TIME 12/12/1998 22:10:10 0#BLDESCRIPTION Sets/returns the band limits.PARAMETERS The frequency band limits (Hz), or none in the GET version.RETURNS The actual frequency band limits, in Hz.REMARKS GET/SET. This is a hidden command (i.e. not available for the normal user in theCMDS list).REMOTE No.EXAMPLE BL 432000000 450000000193 BL 0#BL193 BL 432000000 450000000 0#FREQDESCRIPTION Sets/returns the operating frequency.PARAMETERS The operating frequency and step (Hz), or none in the GET version.RETURNS The actual frequency and step, in Hz.REMARKS GET/SET.REMOTE Yes, SET only.EXAMPLE FREQ 433925000 25000193 FREQ 0#
50SoftwareFREQ193 FREQ 433925000 25000 0#DATADESCRIPTION Returns data stored for a certain device.PARAMETER The ID of the device for which the data is requested and the date/time (in the stan-dard format) the data was stored. If missing, it refers to the data of the local device.RETURNS A data block.REMARKS GET only. If the date/time parameter is not included, the latest data is returned. Ifthe date/time parameter is included, the date and time closest to, but later than, thegiven date/time is returned.REMOTE Yes, for a GET, but only one frame at a time. The A733 can issue the command onlyfor itself, locally.EXAMPLE DATA 193 12/12/1998 12:12:12193 DATA b1 b2 b3 ... bn 0#The data block returned will typically contain a number of data frames (telegrams).The structure of a block is as follows:dd mm yyyy hh mm ss si ft d1 d2 ... dn dd mm yyyy ... dn cswhere:•dd mm yyyy is the date•hh mm ss is the time•si is the size of the frame (21 for frame type 37)•ft is the frame type (37 for the A733)•d1 d2 ... dn are the data values (the frame content)•cs is a 16-bit checksum obtained by summing the bytes and discarding thecarries over 0xFFFF
51CommandsThe A733 devices always respond with a type 37 data frame (see also “Data12” onpage 62). The composition of the data block of such a frame (the values marked asd1, d2... dn) is depicted in Figure 28, while the digibyte is depicted in Figure 29.Figure 28. Frame 37 descriptionFigure 29. The DigibyteThe remote version is limited to a single frame. An example of such a command isgiven below:9999 DATA 9999 30/9/1999 14:50:009999 DATA30 9 1999 14 54 55 21 37 255 255 77 0 0 0 0 89 156 126 20 0 0 0 0 0 0 0 0 0 3197 0#Notice that if you need to get data that is not the last (newest) slot remotely from adevice, the ID must be supplied twice. If you need to get the last slot stored, youcan ignore the ID and the date/time parameters:9999 DATA9999 DATA13 9 1999 19 26 36 21 37 255 255 79 0 0 0 0 87 148 149 15 0 0 0 0 0 0 0 0 0 3148 0RF incomingRF outgoingDigibyte I/O A Pulse Counter I/O B Pulse CounterBattery I/O A Cabling 1 I/O A Cabling 2 I/O A Cabling 3 I/O B Cabling 1I/O B Cabling 2I/O B Cabling 3 I/O C Pulse Counter I/O D Pulse CounterI/O C Cabling 1I/O C Cabling 2I/O C Cabling 3I/O D Cabling 1I/O D Cabling 2I/O D Cabling 3b7 b0SC Dig 6 Dig 5 Dig 4 Dig 3 Dig 2 Dig 1 Dig 0SC — Battery charge (0–off, 1–on) Dig n — Digital I/O n
52Software#IMMEDESCRIPTION Samples all inputs and immediately returns the sampled data.PARAMETER The ID of the requested subsystem, default is the standard A/D subsystem of theA733 (ID=0).Note: Currently only the default subsystem is implemented on the A733.RETURNS A data block.REMARKS GET only. The command needs a certain delay to execute, e.g. for the standard sub-system this delay amounts to two seconds. The delay is necessary to allow for thesensors to settle after applying power to them.REMOTE No.EXAMPLE IMME9999 IMME13 9 1999 19 26 36 21 37 255 255 79 0 0 0 0 87 148 149 15 0 0 0 0 0 0 0 0 0 3148 0#INFODESCRIPTION Returns various status information.PARAMETERS None.RETURNS A list of a device’s internal variables:ID INFO rf_in rf_out date time ver clk stack cop batt temp days_uptimehr:min_uptime rssi pmp_low pmp_high type slot samples err_level#The formats for the above parameters are as follows:•rf_in and rf_out as a decimal (unsigned char)•date as dd/mm/yyyy•time as hh:mm:ss•ver as x.x•clk, stack, and cop as decimal (unsigned char); they represent internalhousekeeping parameters: the A733 uses cop to number watchdog occur-rences, but clk and stack are currently undefined•batt as battery level using the standard voltage conversion equation (0 is 0volts, 255 is 20 volts)•temp as internal temperature in the A733 housing, which is device depen-dent. The precision of the sensing element is low (±2°C), but it is sufficient for
53Commandsbattery power management (charge/discharge). To compute the actual value(in °C), the following equation must be used:•days_uptime in days; together with hr:min_uptime, it represents theamount of time the device is up without a reset or watchdog•hr:min_uptime in hours:minutes format•rssi as decimal (unsigned chars); it is the programmed value with the RSSIcommand•pmp_low and pmp_high are the programmed values with the PMP com-mand•type is used to represent the device type; following types are assigned cur-rently:— 0 for A730MD— 1 for A720— 2 for A730SD— 3 for A720B— 4 for A733•slot and samples are the actual values programmed by means of the SLOTcommand•err_level is the error value; 0 means no errorREMARKS GET only. REMOTE Yes, GET only. The A733 can issue the command both remotely and locally.EXAMPLE INFO193 INFO 255 0 18/4/1999 21:5:11 1.3 0 0 0 91 72 40 1:46 58 65 72 3 900 15 0#RXDESCRIPTION Switches the unit to permanent receive mode (for tuning purposes).PARAMETERS None.RETURNS Nothing.REMARKS The system stops, and exits the command only when a key is pressed. This com-mand returns no message.REMOTE No.EXAMPLE RX193 RX 0#Temp °C[] internalTemp 400⋅255------------------------------------------------- 6 8–=
54SoftwareTXDESCRIPTION Switches the unit to transmit mode (for tuning purposes).PARAMETERS None (sends an unmodulated carrier), 1 (sends a 1 kHz modulated carrier), 0 (sendsa 2 kHz modulated carrier) or 5 (sends a mixed 1 + 2 kHz modulated carrier).RETURNS Nothing.REMARKS The system stops, and exits the command only when a key is pressed. This com-mand returns no message.REMOTE No.EXAMPLE TX193 TX 0#TX 1193 TX 0#TX 5193 TX 0#BDESCRIPTION Sends a broadcast frame.PARAMETERS None.RETURNS A data block.REMARKS After the device sends the broadcast frame, it will listen for answers. All valid an-swers will be listed with their IDs.REMOTE No.EXAMPLE B193 B 0#234 BA 0#7851 BA 04.3.5. Returned errors listFollowing are error messages you might get.Command line interpreter• 1 — nonexistent command• 2 — command line buffer overflow (input line too long)• 3 — internal error
55Returned errors list• 4 — reserved• 5 — missing or false parameters in command• 6 — operation not implementedDevice descriptors and storage handler• 10 — device not found (attempt to perform a command on a nonexistent de-vice)• 11 — device already exists• 12 — reserved• 13 — no more space for descriptors (too many devices)• 14 — no more records for the specified device• 15 — temporary communication break, no more data (the last request was notsuccessful)• 16 — time-out (the handler blocked or is busy)• 17 — internal error• 18 — attempt to insert a reserved device ID number (0 or 65535)Real time clock• 20 — incorrect time supplied (no conversion to time_t was possible)Radio interface• 30 — error at receive (CRC, etc.)• 31 — unexpected frame received• 32 — wrong length• 33 — reserved• 34 — reserved• 35 — time-out (remote device not responding)• 36 — receiver busy (for example, just making the request round)Notifications• 40 — request to read a notification when no notification is pending
56Software4.4. Adcon Packet Radio ProtocolThe A733 is basically intended as an end device in a radio network. Most frames de-fined by the Adcon Packet Radio Protocol are recognized and answered by an A733;a complete list is provided (see “Frame Types” on page 59). In addition, full sourcerouting of frames for other destinations is implemented.Figure 30. State Transition Diagram of the radio communication task.4.4.1. Digital SquelchIn order to reduce the power consumption during receive mode, the unit uses a pro-tocol developed by Adcon Telemetry for the A730 family, but with some additionalrefinements to further reduce the power consumption. The receiver is pulsed at a0.5 seconds interval. At wake-up, the receiver samples first the RF channel for a car-rier, by measuring the RSSI. The RSSI output is extremely stable due to the wide dy-namic range that the IF chip exhibits (over 100 dB, temperature compensated). If thesampled RSSI is under a preset threshold, the unit will immediately go back to sleep.This procedure takes under 20 mS, typically (from wake-up to result).If, however, an RF level superior to the preset threshold is detected, the micropro-cessor will try to detect a valid header, which is composed of a 2 kHz tone of at least0.5 seconds long. The tone detection is performed by the microcontroller in soft-IdleMeasure RFCheckDestinationNo Signal0.5 secInterruptHeader DetectedNot for usGet FrameWe are calledNew Frame PossibleWaitNhops + 1 sandHunt SyncsTimeout ExpiredAnswerAppropriatelyAckResendFrame withLong HeaderFrame Sent TwiceNo AckPayload is for usMust routeUpdateHeaderand SendAckNo Ack
57Modulation Technique Usedware, and takes at most 6 additional milliseconds. If no valid tone is detected, theunit goes back to sleep, otherwise it tries to decode the frame.Based on the destination ID, the frame will be identified. If it is not for that particularunit (own ID), then the microcontroller will cease decoding it and will go immediatelyto sleep. The destination ID is positioned very early in the frame header (see also“Generic Format of a Radio Frame” on page 57).From the above it becomes clear that in order to initiate a communication, a re-quester must send first a header which is at least 0.5 seconds long: these are calledlong header frames. Of course, after the communication is established the headersare short, of only 16 bytes (i.e. 8 msec. – called short header frames). If a timeoutoccurs, the system will restart by sending long header frames.4.4.2. Modulation Technique UsedThe communication via radio is made by using a special MSK (Minimum Shift Keying)scheme; both the encoding and the decoding of the MSK frames is made in soft-ware—there is virtually no hardware modem. A zero bit is transmitted as a sequenceof 250 µs one level followed by a 250 µs zero level, while a one bit is transmitted asa 500 µs one level followed by a 500 µs zero level. A complete sequence of one andzero level forms a bit cell.This modulation scheme is self-clocked. The transmission speed is content-depen-dent, varying from 1 kbps (when sending only ones) to 2 kbps (when sending onlyzeros). On the average, an 1500 bps transmission speed is reached.The data interchange between stations is made by means of frames. The frameshave a header, a 16 bit-sync character, a data block, and a 16-bit CRC number. Thebytes forming the frame are send synchronously, with no start and/or stop bits. Thedata block is assembled after the sync character was detected. The LSB of a byte issent first and the MSB is sent last.4.4.3. Generic Format of a Radio FrameThe standard frame format used by the A730 family is as follows:00 011100 00 ....... 00 0xAA DST-H DST-L SRC-H SRC-L DLEN .......DATA1 DATA2 DATAn CRC-H CRC-LData Frame
58Software• The frame starts with a header of zeros and there are two header types: longand short. The long headers are used to wake up a remote station and mustbe 140 bytes long, while the short headers are only 16 bytes long.• After the header, a synchronization character is used; this is a hex 0xAA byte.The implementation must ensure that a 16-bit sync character is checked, i.e.0x00AA, and not only an 8-bit 0xAA character.• Following the synchronization pattern, the bytes are assembled by shiftingthe bits one by one: each 8 contiguous bits will be “cut” into a byte. First in-formation assembled is the destination (DST) address: this is in order for allthe receiving stations to know if they must assemble the whole frame, or theycan go back to sleep. Only the addressed station will remain active after thisinformation was decoded.Note: The byte ordering convention used on the network is “big endian,” i.e. the MSB is sent first and the LSB last.• Next are the source (SRC) address and the length of the data field. The datafield follows, and the frame is ended by a 16-bit CRC field. The CRC is com-puted starting with the first byte after the SYNC character until (but not in-cluding) the CRC bytes.The data field can transport various type of data frames. After being successfully de-coded and checked, these data frames are passed to the upper layer of the soft-ware. The data frames recognized by the A733 and their answers are detailed in“Data Frames” on page 59.A device will answer to the requesting device with the answer frame. The answeringdevice will poll the radio channel for an acknowledge; the acknowledge may be ei-ther the same frame send further up the network (if the communication has hops, i.e.routing stations in between the master and remote device), or an acknowledge sendby the master – the master sends only a short radio frame containing the SRC andDST, both being its own ID. If the answering device does not receive the acknowl-edge, it will repeat the frame after a one second delay (only once).Another notable feature of the system is the way it handles the long and short head-er frames. When a frame is sent by the master for the first time, it will be one with along header; all the stations on the path of the frame participating in a certain trans-action will relay the frame with a long header. After relaying the frame, the stationswill remain active for a time calculated as (in seconds):The above scheme assures that as long as another frame will follow during this timeinterval (addressed to a station that is known to be also active), the header sent tothat station will be a short one.Delay Hops 1+=
59Data Frames4.4.4. Data FramesThe data frames (payload) are the blocks of data extracted from the radio frames,after the CRC and other information (source address) was checked. The data frameand its length are passed to the upper layers of the software.Figure 31. Generic Data Frame structure.A data frame is composed of two main parts: a header, containing the frame type aswell as the routing information, and a data block. The length of the data block canbe easily computed by subtracting the header length (HLEN + 1 byte for the TYPE)from the original data frame length received from the lower layer of the software (theradio frame length). Additional explanations on the notation used in the diagram:•TYPE is the type of frame; the types recognized and/or used by the A733 willbe detailed individually later in this chapter (see “Frame Types.”)•HLEN is the header length: it represents the number of bytes used to de-scribe the route the frame will go (or went). The maximum number of hops is8, that is, 8 intermediate stations plus source and destination. Each station isdescribed by its unique 16-bit address.•SRC, HOP and DEST, are the source, the hops and the destination addresses.While the hops may be missing (no routing stations between source and des-tination), the source and destination are mandatory.•DATA is the data proper field. It is limited in length, its maximum size beingdependent also on the particular route: if the route is longer (8 hops) then thedata block is limited to 48 bytes. Depending on the frame type, the data blockmay be nonexistent (zero length).4.4.5. Frame TypesAlthough the original Adcon Packet Radio Protocol contains many frame types, onlythose relevant to the A733 are presented here.RequestID 1FORMAT struct {time_t init_time;time_t req_time;} request;DESCRIPTION The Request frame is used by a master to request data frames from a remote station.A remote will answer with a data frame. There are currently three types of dataTYPE HLEN SRC-H SRC-L .......HOP1-H HOP1-L HOPn-H HOPn-L DEST-LDEST-H DATA1 DATA2 DATAn.......Header (Frame Type + Routing Information) Data
60Softwareframes: normal (type 8), extended (type 37), and reduced (type 38); the A733 an-swers with the extended type (see also “Data12” on page 62).•init_time represents the actual time to be used by the remote to re-initializeits local RTC; if its value is time_t NULL (default), then no re-initialization willbe performed.•req_time is the time for requested data. An A733 will search its internal databuffer for data that has a time stamp that is strictly newer than req_time.Therefore, if a master requests data with exactly the time stamp previouslysupplied by the remote, the remote must deliver a newer data slot. If the re-quested data is too old, the remote will send its oldest data, while if the re-quested data is too new, the remote will answer with the newest data it has.If the device is not yet initialized and has no data (i.e. its internal time is 1/1/1970), then it will send a Data12 frame with no relevant data, but with the timestamp of 1/1/1970. This mechanism will inform a master that the device needsinitialization.On the A733 this command can be initiated by means of the DATA command (seealso “DATA” on page 50).SEE ALSO Data12 frame.Broadcast AnswerID 2FORMAT struct {unsigned char RF_levelOut;} broadcast_answer;DESCRIPTION This is the answer to a broadcast request frame; the RF_levelOut is the level record-ed by the device when receiving the broadcast request frame. The A733 will receiveand interpret such frames depending on the mode it was in when it issued thebroadcast request (see also “Broadcast Request” on page 60). In terminal mode, allthe broadcast answers will be displayed with their RF levels, while in connectivitycheck mode, the LED tool will be activated. The device will pulse the LED tool forthe number of answers it identified. If the A733 receives a Broadcast request, it must answer to it, but in a random man-ner. An 8 seconds time interval starting with the end of the Broadcast request frameis divided in 16 slots, each 0.5 seconds long. The A733 must select randomly one ofthese 16 slots for sending its answer. This frame, as well as the Broadcast requestframe, is not routable.SEE ALSO Broadcast Request frame.Broadcast RequestID 6FORMAT The data frame body is empty.
61Frame TypesDESCRIPTION This frame is sent by the device when the LED tool is inserted in the POWER con-nector, or if the command B is issued in terminal mode. This frame is special in thatthe destination address (DST) in the header is 0. This type of frame is not routable.All devices having received this frame must reply in a random fashion with a Broad-cast answer frame.SEE ALSO Broadcast Answer frame.PingID 9FORMAT The data frame body is empty.DESCRIPTION This frame is used to request an answer from a device; it is used to check if the de-vice is available and reports on various conditions of the remote. The addressed de-vice must answer with a Pong frame. On an A733, this command can be initiatedfrom the terminal by means of the INFO command (see also “INFO” on page 52).SEE ALSO Pong frame.PongID 10FORMAT struct {unsigned char RF_levelIn;unsigned char RF_levelOut;time_t RTC;unsigned char version;unsigned char clkfail;unsigned char stackfail;unsigned char WDT;unsigned char batt;unsigned char internalTemp;time_t uptime;unsigned char rssi;unsigned char pmp_low;unsigned char pmp_high;unsigned char type;unsigned int slot;unsigned char samples;} pong;DESCRIPTION The Pong frame is an answer to the Ping frame. In addition to informing a caller thata remote is active, it carries some useful information about the device’s status:•RF_levelIn is the left zero (it is a placeholder and will be filled by the first de-vice receiving the frame).•RF_levelOut is the RF level measured by the device when receiving the Pingframe.•RTC is the actual value of the remote’s Real Time Clock.
62Software•version is the software/hardware version of the device.•clkfail and stackfail are meaningless for an A733; they are kept for histor-ical reasons.•WDT is a counter incremented each time the device was reset due to a Watch-dog timeout; its value is cleared at power-on reset.•batt is the battery voltage (this value will be also found in the Data frame).•internalTemp is the temperature in the A733 housing; the precision of thesensing element is vry low (±2C°), but it is sufficient for battery power man-agement (charge/discharge). To compute the actual value (in C°), the follow-ing equation must be used:•uptime is the time elapsed since the last reset (including a Watchdog reset).•rssi is the programmed RSSI threshold value.•pmp_low and pmp_high are the programmed power management parameters.•type is the type of the device (will return always 4 – for A733).Note: Some of the values described above are specific to the A733. The implemen-tation of the Pong frame, as well as its length (number of bytes), may vary from one device type to another.SEE ALSO Ping frame.FdevID 32FORMAT The data frame body is empty.DESCRIPTION This frame requests that a remote clear its data memory (format). The remote willanswer with a General acknowledge frame. An A733 will never issue this frame type,but it will execute and answer it.SEE ALSO General Acknowledge frame.Data12ID 37FORMAT struct {unsigned char RF_levelIn;unsigned char RF_levelOut;time_t slot_timeStamp;unsigned char digibyte;unsigned int counter0; /* Pulse Counter I/O A input */unsigned int counter1; /* Pulse Counter I/O B input */unsigned int counter2; /* Pulse Counter I/O C input */Temp °C[] internalTemp 400⋅255------------------------------------------------- 6 8–=
63Frame Typesunsigned int counter3; /* Pulse Counter I/O D input */unsigned char battery;unsigned int analog_data[9];} data_frame;DESCRIPTION This frame will be sent back by the device as an answer to the Request frame.•RF_levelIn is the left zero (it is a placeholder and will be filled by the first de-vice receiving the frame).•RF_levelOut is the RF level measured by the device on the Request frame.•slot_timeStamp is the actual time stamp on the data sent.•digibyte represents the result of OR-ing the following bits:— SC represents the battery charge switch’ status.— DIG0 to DIG7 are the I/O pins on the I/O connectors. Note that only thefirst 4 DIGs are usable (there are only four I/O connectors on the A733).Note: For additional info on the bits in the digibyte, check the hardware section of this manual.•counter0 to counter3 are the values of the pulse counters.•battery is the value of the main power supply; its actual value can be com-puted using the equation:•analog_data[9] is an array of 8 unisgned integers that represents the result ofpacking the 12 12-bit values. These are the values returned by the internal A/D converter from the respective I/O connectors (see the hardware sectionfor more details). The packing mechanism is depicted below:SEE ALSO Request frame.Set IDID 40SC Dig6 Dig5 Dig4 Dig3 Dig2 Dig1 Dig0b0b7Batt V[] battery 20×255-------------------------------=16 bit values8 bit packed valuesInteger 0 Integer 1 Integer 2 Integer 312 bits 12 bits 12 bits 12 bitsByte 0 Byte 1 Byte 2 Byte 3 Byte 6Byte 5Byte 4 Byte 16 Byte 17
64SoftwareFORMAT struct {unsigned int ID;} setId;DESCRIPTION This frame requests a remote to change its own ID number. The remote will answerwith a General acknowledge frame before changing its ID. An A733 will never issuethis frame type, but it will answer to it.SEE ALSO General Acknowledge frame.Set Slot Time and Sample RateID 41FORMAT struct {unsigned int slot;unsigned char rate;} setSlot;DESCRIPTION This frame requests that a remote change the size of its slot (default 900 seconds,i.e. 15 minutes) and the sampling rate (default 15).•slot is the number of seconds a new slot of sampled and averaged data willbe stored in the internal FIFO memory of the device.•rate is the number of samples per slot taken; these samples will be averagedbefore being stored.The remote will answer with a General acknowledge frame. An A733 will never issuethis frame type, but it will answer to it.SEE ALSO General Acknowledge frame.Set FrequencyID 42FORMAT struct {unsigned long frequency;unsigned int step;} setFreq;DESCRIPTION This frame requests that a remote change its frequency. The remote will answer witha General acknowledge frame before changing its operating frequency. To furthersecure the transaction, the frequency change will be performed only after the re-mote receives the acknowledge frame from its next neighbor (for more details, seealso “Generic Format of a Radio Frame” on page 57). An A733 will never issue thisframe type, but it will answer to it.SEE ALSO General Acknowledge frame.
65Frame TypesSet Battery Charge LevelsID 43FORMAT struct {unsigned char chargeStart;unsigned char chargeStop;} setBattCharge;DESCRIPTION This frame requests that a remote change the battery charge management param-eters. The device will answer with a General acknowledge frame. An A733 will neverissue this frame type, but it will answer to it.•chargeStart is the value where the external power (normally a solar panel) willbe enabled to charge the battery.•chargeStop is the value where the external power will be switched off.From the above two values, the system will compute all other limits (e.g. misery, bat-tery low, etc.).SEE ALSO General Acknowledge frame.General AcknowledgeID 127FORMAT struct {int result;} generalAck;DESCRIPTION This frame is sent as an acknowledge to various Set type of frames. The result fieldis NULL if the request was successfully performed; in case of failure, this field maycontain information about the cause of the failure. Its value will depend on the typeof the request.

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