Atmega 328 & raspberry pi - I2C communication

Hello all. I would like to use an atmega 328 chip ( standalone , without the arduino board ) with the arduino bootloader to read some sensors inputs and send the values through i2c at the raspberry pi.

So my question is: how easy is it to directly connect the Atmega328 with the R-pi? Is there any schematic to help with what I need to do?

I don’t know about i2c , but I have tried using a simple serial connection.

I used a Attiny85 and even a Attiny13. I powered it from the RPI 3.3V, so no level converter needed.

Edit: just found this:

http://arduino.cc/forum/index.php/topic,145867.0.html