A720 – addIT™ Technical Documentation Adcon Telemetry GmbH Inkustr. 24, A-3400 Klosterneuburg Austria Tel: +43-2243-38280 Fax: +43-2243-38280-6 http://www.adcon.at Adcon Telemetry, Inc. 1001 Yamato Road, Suite #305, Boca Raton, FL 33431 USA Tel: +1-561-989-5309 Fax: +1-561-989-5310 http://www.adcon.com Adcon Telemetry srl. Bd. Ana Ipãtescu nr. 27 ap. 11 R-71111 Bucharest Romania Tel: +40-1-312-6886 Fax: +40-1-312-6668 http://www.adcon.
Proprietary Notice: The Adcon logo, the A730 series, addIT™, addVANTAGE and AgroExpert™ are trademarks or registered trademarks of Adcon Telemetry GmbH. All other registered names used throughout this publication are trademarks of their respective owners. This publication contains confidential information property of Adcon Telemetry GmbH. Disclosure to third parties of the information contained herein is prohibited.
Table of Contents 1. About the A720 2. Hardware 5 6 2.1. The Radio Unit 6 2.1.1. Receiver Section 6 2.1.2. Synthesizer Section 8 2.1.3. Transmitter Section 9 2.2. The Modem Interface 9 2.3. The Microcontroller and the Power Management Sections 2.4. The Interface Board 11 3. Tuning Procedure 12 3.1. Programming the Boards 13 3.2. Setting-up the Default Parameters 3.3. Tuning 10 13 13 3.3.1. Definitions 14 3.3.2. Test Equipment Settings 15 3.3.2.1. Network Analyzer (HP 8711) 15 3.3.2.2.
3.4.1. Controlling the Unit 19 3.4.2. External Power Supply 19 3.4.3. Specifications 20 3.4.4. Bill of Materials 24 3.4.5. Device Photographs 29 4. Software 4.1. AMOS 34 34 4.1.1. Initialization 35 4.1.2. 1/2 Second Interrupt 36 4.1.3. Pulse Counters Interrupt 36 4.2. Mode Check 4.3. A/D Task 36 38 4.4. The Terminal Task 39 4.4.1. Supported Commands 39 4.4.1.1. The SET Series of Commands 39 4.4.1.2. Querying the Actual Configuration Parameters 41 4.5. The Radio Interface Task 41 4.5.1.
Wireless Sensor Interface A720 (addIT™) 1. About the A720 The A720 Wireless Sensor Interface (also known as addIT™) is a low power, short range telemetry device, capable of sampling up to 6 analog sensors and 4 digital inputs (of which 2 counter types); in addition, it can control two relays. The frequency of operation is in the 432 to 470 MHz range, making it adaptable to most radio communication regulations in the world. The output power is under 10 mW, while the modulation is narrow band FM (12.
Wireless Sensor Interface A720 (addIT™) 2. Hardware Most of the electronics are situated on the main board, while an interface board is used to connect the unit to the outside world. The main board contains a radio unit, a low speed modem interface, a microcontroller and a power management subsystem.
Wireless Sensor Interface A720 (addIT™) chip, a third-overtone quartz oscillator oscillating on 44.545 MHz. The 12.5/25 kHz selectivity is obtained through the use of the two ceramic filters CF1 and CF2 (version GX for 12.5 kHz or EX for 25 kHz channel spacing), exhibiting a low group delay time. An interesting feature of U10 is its coilless demodulator, which is PLL based. By adjusting R67 and R60 one can change the bandwidth and the central frequency of the IF demodulator.
The Modem Interface 2.1.3. Transmitter Section The transmitter section uses the VCO composed by Q2/Q1. This VCO is modulated on the anode of its varicap diode (D3) by means of a small amount of the data signal. Before modulation, the data signal is filtered by a four-pole low-pass filter built around U1. The filter effectively removes the harmonics on the data signal in order to keep the adjacent channel power under the required level.
Wireless Sensor Interface A720 (addIT™) 2.3. The Microcontroller and the Power Management Sections The operation of the whole unit is under the control of U9, a PIC16C77L microcontroller. It is a powerful chip exhibiting an extreme low power consumption.
The Interface Board must be performed thus driving the unit in the hibernation mode. If the unit was completely switched off due to an extremely low battery level, Q10 would start it up again only if external power is applied to the power connector (e.g. from a solar panel). The terminal mode is implemented by means of the built-in UART.
Programming the Boards 3.1. Programming the Boards This section will be completed later. 3.2. Setting-up the Default Parameters The tuning procedure is not possible without first configuring some default parameters on each unit. This is done using a special serial cable connected between the A720MB with an A720CA interface to a PC; in addition, a communication terminal program (e.g. Hyperterminal, in Microsoft® Windows™ 95) is needed to send the commands.
Wireless Sensor Interface A720 (addIT™) 3.3.1. Definitions The diagram of the setup environment is depicted in Figure 3. Scope Service Monitor Network Analyzer Voltmeter 0.765 V Optional Out Scope In/Out Service Monitor RS232 To/From PC A720MB Connector Testing Fixture Figure 2. In Out Out Network Voltmeter Network Analyzer Analyzer Power/ Sens + 6.5 V – Wobble Trimming Setup.
Tuning There are only three tuning elements to be acted upon: FL3, L6 and L10. Their location on the PCB (all upper side) is depicted in the schematic below: FL3 L10 L6 3.3.2. Test Equipment Settings Before proceeding, certain controls on the test equipment must be set; some of the settings 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 trimming is 24° C (±2°C). 3.3.2.1.
Wireless Sensor Interface A720 (addIT™) The settings for the transmitter section check (TX-TEST): • COUNT: (should show the transmitter carrier frequency); • POWER: (should show the transmitter carrier power). Note: 3.3.3. If using the Testing Fixture, a calibration should be performed to check the losses in the antenna switch, cables, etc. Depending on these losses (which at 450 MHz can amount up to 6 dB), it may be needed to adjust the RF LEV value accordingly (up to 10 µV).
Tuning 3.3.4. Adjusting the VCOs • Flip the switch on the Testing Fixture to the Power/Sens.
Wireless Sensor Interface A720 (addIT™) • Check if the RSSI threshold is correct: type the command RSSI – the actual value must be lower than the threshold set. If this is not the case, repeat several time the RSSI command, maybe a transmission just happens (a radio scanner set on the operating frequency would help detect foreign transmissions). If the threshold difference is marginal, then you must increase it by using the SET RSSI command (it must be 20 to 30% higher than the actual value).
Additional Issues Related to Type Approval Testing The test is performed by entering at the terminal prompt the command B: the base and/or remote station must answer with the RF in and out values. If no answer is received after several seconds, then retry the command. If still no answer is received, then check with a scope on TP2 if the digital data is present (on receive); if not available, check U8:C and the parts around it.
Wireless Sensor Interface A720 (addIT™) WARNING! Do not apply more than 10 Volts to the unit: permanent damage of the de- vice may result. Note also, that the internal microcontroller will switch off the unit when the battery voltage drops below 5.5 Volts, and under 5.9 Volts the RF operations may be stopped. Power Cable Serial Adapter Cable + POWER RS232 + I/O B Red + I/O A Black 5 to 10 Volt - Figure 5. 3.4.3. Connection of an external power supply.
Additional Issues Related to Type Approval Testing Parameter Min Typ Local Oscillator Leakage Max Unit 2 nW Adjacent Channel Attenuation (both versions) 70 dB RSSI dynamic 90 dB Operating Current (incl. On-board Microcontroller) 15 mA 10 dBm 2 nW Spurious Radiation (862 MHz to 3.5 GHz) 200 nW Adjacent Channel Power (12.5 kHz version) -32 dBm Adjacent Channel Power (25 kHz version) -44 dBm Occupied Bandwidth (12.5 kHz version) 8.
Wireless Sensor Interface A720 (addIT™) Several graphs obtained by means of a Rohde & Schwarz Spectrum Analyzer (model FSEA) are attached, reflecting some of the measured parameters. 22 Figure 6. Spurious radiations (Marker 2); except the second harmonic, no other overtones are visible. Figure 7. Adjacent Channel Power, 460 MHz, 12.5 kHz version, modulated with a 0x55 tone (1500 bps).
Additional Issues Related to Type Approval Testing Figure 8. Spectral purity: an unmodulated carrier at 460 MHz is shown. Figure 9. The TOP side of the printed circuit board. Figure 10. The BOTTOM side of the printed circuit board.
Wireless Sensor Interface A720 (addIT™) Figure 11. 28 The VCTCXO Specification. This part is used as frequency reference for the PLL synthesizer.
Additional Issues Related to Type Approval Testing 3.4.5. Device Photographs Figure 12. General view.
Wireless Sensor Interface A720 (addIT™) 30 Figure 13. Front view. Figure 14. Bottom view.
Additional Issues Related to Type Approval Testing Figure 15. Back view. Figure 16. Top view.
Wireless Sensor Interface A720 (addIT™) 32 Figure 17. Left view. Figure 18. Right view.
Additional Issues Related to Type Approval Testing Figure 19. The A720 Opened. TOP BOTTOM Figure 20. The PCB.
Wireless Sensor Interface A720 (addIT™) 4. Software The software is written entirely in C. It consists of a collection of standard C library functions, a minimalistic operating system (AMOS – Adcon Minimal Operating System) offering basic configuration and administration functions (including a command line terminal on a serial port), and the application software itself which assures the desired functionality of the device.
AMOS order to reduce their consumption to a minimum; all operations are executed in the shortest possible time. Reset 0.5 sec Interrupt Initialization No Increment the RTC? Sleep Yes Advance the RTC one second No 0.
Wireless Sensor Interface A720 (addIT™) 4.1.2. 1/2 Second Interrupt The interrupt handler will only increment the RTC, when needed (every other interrupt); no other tasks are performed on this interrupt level. The interrupt is generated by TIMER1 of the microcontroller. 4.1.3. Pulse Counters Interrupt Interrupts are generated by two pins on the PORTB, having the Interrupt on Change feature.
Mode Check • Terminal mode: the device notices that a serial cable is connected to its POWER connector, and is ready to accept commands. In this mode, all the subsystems are enabled (A/D, pulse counters, radio interface, etc.), and the complete functionality of the device is available. • Connectivity check mode: in this mode, a special tool is plugged in the POWER connector, in order for a user to check if the device is able to contact other devices (normally an A730MD or an A730SD).
Wireless Sensor Interface A720 (addIT™) More details on the functionality of each mode will be described when dealing with the individual tasks. 4.3. A/D Task This task is responsible for the actual sampling of the A/D inputs (where the sensors are connected).
The Terminal Task The A/D task is not executed at each 0.5 seconds interval, but rather every 5 minutes (default). This parameter can be user configured (it is stored in the EEPROM section). After the sensors inputs are sampled their values are averaged and stored as a slot in the EEPROM FIFO buffer, time stamped. The number of samples is by default 3, but is user configurable (this parameter is stored in the EEPROM section).
Wireless Sensor Interface A720 (addIT™) to build the average that will be stored. The default storage is 900 (15 minutes) and samples is 3 (3 samples per quarter of an hour). Example: — if you want to sample the inputs (sensors) every minute and build an hourly average, issue the command SET SLOT 3600 60. — if you want to sample the inputs once per hour and store the values as they are, then the command SET SLOT 3600 1 will do the job.
The Radio Interface Task Note: 4.4.1.2. The values of RSSI have no units, they are arbitrary; however, a value of 85 corresponds more or less to the maximum value in addVANTAGE, i.e. 8 µV. Querying the Actual Configuration Parameters You can query an addIT to find out its actual configuration parameters. Typing OWNfor instance will return the actual ID an addIT answers to (it should be the same as the one on its label).
Wireless Sensor Interface A720 (addIT™) • Note: – sets remotely certain parameters (id, frequency, slot, power management parameters). RSET RSETIO frame is provided only for backwards compatibility with the A730MD. Better ways to control the ports will be implemented at a later date. The device will not recognize a broadcast frame and will not answer to such frames. It will however send a broadcast and wait for answers in the Connectivity Check Mode, or if a Broadcast command is issued at the terminal.
The Radio Interface Task pled RSSI is under a preset threshold, the unit will immediately go back to sleep. This procedure needs under 20 mS, typically (from wake-up to the result). If however, a RF level superior to the preset threshold is detected, the microprocessor will try to detect a valid header, which is composed of a 2 kHz tone of at least 0.5 seconds long. The tone detection is performed by the microcontroller in software, and takes at most 6 additional milliseconds.
Wireless Sensor Interface A720 (addIT™) 4.5.3. Generic Format of a Radio Frame The standard frame format used by the A730 family (and therefore by the A720) is as follows: 00 00 ....... 00 0xAA DST-H DST-L SRC-H SRC-L DLEN DATA1 DATA2 ....... DATAn CRC-H CRC-L Data Frame • The frame starts with a header of zeroes; there are two header types: long and short. The long headers are used to wake-up a remote station and must be 140 bytes long, while the short headers are only 16 bytes long.
The Radio Interface Task As long as another frame will follow in this time interval addressed to a station that is known to be also active, the header sent to that station will be a short one. 4.5.4. Data Frames The data frames are the blocks of data extracted from the radio frames, after the CRC and other information (source address) was checked. The data frame as well as its length are passed to the upper layers of the software. TYPE HLEN SRC-H SRC-L HOP1-H HOP1-L .......
Wireless Sensor Interface A720 (addIT™) } 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 two types of data frames: normal and reduced – the A720 answers with the reduced type – see also “Data” on page 49).
The Radio Interface Task 4.5.5.4. Read I/O Answer ID 4 FORMAT struct { unsigned unsigned unsigned unsigned } readio_answer; RF_levelIn; RF_levelOut; DDR; PORT; This is the answer to a Set I/O request frame. It returns the actual state of the port and its data direction register. DESCRIPTION 4.5.5.5. char char char char Broadcast Request ID 6 FORMAT The data frame body is empty.
Wireless Sensor Interface A720 (addIT™) DESCRIPTION The Pong frame is an answer to the Ping frame.
The Radio Interface Task 4.5.5.9. Memory Dump Answer ID 21 FORMAT struct { unsigned int unsigned char unsigned char } memoryDump_answer; This is the answer to a Memory dump request frame; although the frame has a flexible format, an A720 will always return 32 bytes of data. DESCRIPTION 4.5.5.10.
Wireless Sensor Interface A720 (addIT™) • analog0 to analog2 and analog4 to analog6 are the values returned by the internal A/D converter from the respective connectors (see the hardware section for more details). • internalTemp is the temperature in the A720 housing (it’s the same value transmitted with a Pong frame – see “Pong” on page 47 for more details). 4.5.5.11. Set ID ID 40 FORMAT struct { unsigned int } setId; DESCRIPTION 4.5.5.12. This frame requests a remote to change its own Id number.
The Radio Interface Task “Generic Format of a Radio Frame” on page 44). An A720 will never issue this frame type, but it will answer to it. 4.5.5.14. Set Battery Charge Levels ID 43 FORMAT struct { unsigned char unsigned char } setBattCharge; DESCRIPTION chargeStart; chargeStop; This frame requests a remote to change the battery charge management parameters. The device will answer with a General acknowledge frame. An A720 will not issue such a frame, but it will answer to it.
