Hab grad ne Seite mit C Bibliotheken gefunden, die sehr interessant sind.
http://www.procyonengineering.com/avr/avrlib/

"I2C Serial Interface Function Library
This library provides the high-level functions needed to use the I2C serial interface supported by the hardware of several AVR processors. The library is functional but has not been fully tested yet and is still expanding. Thanks to the standardization of the I2C protocol and register access, the send and receive commands are everything you need to talk to thousands of different I2C devices including: EEPROMS, Flash memory, MP3 players, A/D and D/A converters, electronic potentiometers, etc."

Da gibts sogar was für GPS, IDE/ATA, Graphik LCD usw. Die Seite ist überhaupt sehr interessant hab sie grad erst gefunden.
Muraad