“This project describes a simple GPS module which you can interface to via I2C. It uses an ATtiny841:
Introduction
Incorporating GPS into a project is quite daunting. First you have to parse the NMEA sentences from the GPS module you’re using, and then if you’re doing any calculations with the received longitudes and latitudes, you need to incorporate a floating-point GPS library with routines to perform the calculations.
If you need to do any other significant processing there’s a chance that the GPS handling may interfere with your other tasks. Providing the GPS processing as a separate I2C module solves this problem.
I originally designed this to provide GPS support to boards running my Lisp interpreter, uLisp, but it could be useful for any other application where you want GPS data accessible via a simple I2C interface. It is based on my earlier project Making Your Own I2C Peripherals which described how to make an I2C slave device based on an ATtiny841.”