The TinyShield GPS lets you get position data using GPS on your TinyDuino. This TinyShield is based around the Telit JF2 GPS Module, which uses the popular SiRFstar IV chipset. This module is configured by default to output GPS strings in the NMEA format at a 1Hz update rate (this can be changed to a 5HZ updated with a NMEA command).
Note: The integrated GPS antenna is used to keep the overall product size very small and is not as sensitive as larger GPS antennas. This antenna will not pick up GPS signals indoors and will only work well outdoors. For best results, keep all metal aware from the antenna and make sure it is used in an outdoor environment.
GPS TinyShield Signals:
|A0||GPS RX||This signal is the serial TX out of the TinyDuino and the RX into the GPS module.|
|A1||GPS TX||This signal is the serial TX into the TinyDuino and the TX out of the GPS module.|
|A2 (optional)||SYS-ON||This signal is an output the GPS module to indicate if the module is in an active mode (the signal is a logic-high “1?) or in hibernate mode (the signal is a logic-low “0?). By Default this signal is connected between the GPS module and the A2 signal using R7, which is a 0 ohm resistor. This resistor can be removed if this signal is not needed to free up A2 for other uses.|
|A3||ON-OFFr||This signal is an input into the GPS module, and is used to transition between hibernate and active modes. Transitions between states are made with a low to high pulse on this signal (minimum time of 100uS).|
The Telit JF2 module draws between 25mA – 50mA when operating (not in hibernate mode), so a coin cell battery is not sufficient to run this board.
The GPS TinyShield includes a local voltage regulator and level shifters, so your TinyDuino system can operate from 3 – 5 Volts safely.
Upon power up, the GPS takes approximately 3 seconds to stabilize before it can be put into active mode. To wake up the module, a low-to-high pulse is needed on the ON-OFF pin of the module, which is connected to the Arduino A3 pin.
After waking, the module will start to stream out NMEA data every 1 second on the UART.
The system can also be put back into hibernate mode with a pulse on the ON-OFF pin again.
Note: A number of the revision 5 TinyShields have modules configured to run at 4800 baud instead of 9600 baud. So if during testing the module does not seem to work at 9600, try it at 4800 baud.
We’ve tested the GPS TinyShield with the popular TinyGPS / TinyGPS++ library for Arduino. This following example uses the TinyGPS++ library written by Mikal Hart, which handles the GPS/NMEA Parsing. You can find more information about this library and download the latest version at this link: http://arduiniana.org/libraries/tinygpsplus/