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The Aarlogic GPS 3A GPS module and TELIT GC864 GSM module are available from www.roundsolutions.com and are now supported by the Open GPS Tracker.

Using the Aarlogic GPS 3A module

The Aarlogic GPS 3A module is a direct replacement for the Tyco module. It can be used with any build of the Open GPS Tracker. This module has five large solder pads on the back, and is easy to connect up. You do not need a standby power diode, because the module has a battery on it.


AarLogic-GPS-3A.pdf datasheet

Update: Please ignore the command below. This module uses battery-backed memory to store its settings. If you only power it occasionally, it defaults back to 9600. Therefore when using this module, I run the tracker at 9600 baud by halving the baud divisor.

The datasheet claims the module defaults to 4800 baud, but mine came set to 9600. You can change the baud rate with the command:

$PSRF100,1,4800,8,1,0*0E
Send the command to the module via its data input line, at 9600 or whatever the baud is set to, followed by CR and LF (characters 13 and 10), and the baud rate should change immediately. You can use a level converter or a CMOS level USB to Serial device to send this command, and to test the module. It uses 3.3 volt power.

Using the TELIT GC864 GSM module

THe TELIT GC864 is a quad band GSM module, and is supported by a PHONE_TYPE option in Build 19B. If you have surface mount capability, you could build a very small commercial tracker around this module, and I hope someone does that soon. For hobbyist construction you need the RS-EB-S3 board, which provides 0.1 inch pins.

You must set the band correctly before the module will work. For the USA, the command is: 

AT#BND=3
This setting is stored permanently unless you change it. Europe would probably use AT#BND=0. The module pinouts and AT command set are available on Round Solutions' website.

Build 19 has the ability to turn this module on and off, and reset it automatically. You need two transistors to drive the pull-down ON/OFF and RESET inputs. See the build 19 description for more information.