The GPRS Shield is one of the easiest ways to interact with your mobile device, even if it ends up in some field on the other end of earth. As long as that field has a cellular connection, you'll be good to go.
With this Arduino expansion board, your device gains the capabilities of a mobile phone. In practice, you can use it to:
- send SMS commands to the device
- request status or receive notifications via SMS
- Call the device and change its IVR-script
- receive calls from the device and listen to what is happening
- go online, pull from web services, log data
You can control your heater via GSM from out of the country, make a realistic toy phone for your child, monitor the basement or the garage, and much, much more.
The GPRS Shield is compatible with both Arduino and Iskra boards, working at 5 V and 3.3 V respectivly.
The board is based on the SIMCom SIM900R module. In addition to the chip itself, we have also added:
- A slot for a full-size SIM card from your favorite operator
- Standard 3.5 mm jacks for speaker and microphone connection
- Socket for a CR1225 battery which provides power for the operation of the built-in real-time clock
- Standard SMA-connector for an external antenna
- Connectors and tinned holes for resetting control pins, if necessary
If you do not plan to use a voice GSM connection, you do not have to connect the headset.
Similarly, if there is no need for a real-time clock, you will not need a battery.
SMA-connector can take many different antennas: on a magnet, on sticky tape, large, small, with an extension or without. In the kit we have included a single vertical antenna with a gain of 2 dB, which allows for good reception in most areas.
Management and Programming
Communication with the board is done via UART using a set of AT commands: GSM 07.07, 07.05, SIMCom enhanced AT commands. The SIM900R chip is pretty smart, it lends itself to the usage of hundreds of AT commands. The main functions for working with SMS, calls, and GPRS-Internet are accessible via convenient functions in specially prepared libraries.
The GPRS Shield uses 4 pins:
- 0 (TX) and 1 (RX) - send and receive data via UART
- 2 (PK, Power Key) - pin to turn the chip on and off
- 3 (ST, Status) - pin to check the status of the chip
If necessary, to avoid conflicts with other expansion boards, you can to move some or all of the pins. To do this, remove the corresponding jumper and connect a female-male jumper cable with any another pin on the board, or you can solder to the tin holes and use the usual jumper.
- GPRS Shield board
- Vertical antenna with 2 dB gain
- Number of Bands - 2: 900, 1800 MHz
- GSM Class - "2+": defines a set of telephony capabilities, 2+ - the last, long-established standard
- GPRS Class - "B": as in most mobile phones, either GPRS (data) works simultaneously, or GSM (SMS, voice). For the duration of GSM, the activity of GPRS is suspended
- Multislot Class - 8/10: up to 4 timeslots from network to subscriber, up to 2 timeslots from subscriber to network, which means up to 85 Kbps for downloading and up to 42 Kbps for uploading
- The output power of the module is Class 4 (2 W) at 900 MHz. Class 1 (1 W) per 1800
- The current draw depends on the operating mode and ranges from 20-30mA to 500mA. Also short-term jumps up to 2-3A are possible, especially when searching for a network or data reception / transmission.
- Current Draw in Sleep Mode: 1 mA
- Supply Voltage at Vin: 7-12 V