The latest project from Lucidscience.com is a simple AVR based GPS tracker. As usual, the instructions here are quite in-depth including schematics and step by step procedures all the way down to modifying cables when necessary. What we found interesting is that the GPS module he’s using is so simple. It only requires 3 wires, one for power, one for serial communication, and one for a heartbeat.
For the microprocessor, he’s using an ATMega 324, which is a bit of processing overkill but he needed the SRAM for the GPS point storage. You could obviously expand to external storage but the goal here was to keep it extremely simple. Actually, there just isn’t a whole lot here other than the microprocessor, the GPS module, and a level converter. After wrapping up the circuit he goes on to explain how to get the data into Google Earth for display. After a few trips around the block you can see the results are quite nice.