In the last entry for the Timed LED Lighting Controller, I realised that there are no working examples of an I²C driver for the ATtiny20. I then had to work through the data sheet to implement my own. With that done, I could then start on the application firmware and get the board really working. So this is where my proof of concept becomes the prototype.
In this post I describe the trials an tribulations of bringing up my Timed LED Lighting Controller and how I went about implementing my first I²C Slave Driver for the ATTiny20.