It’s the middle of the night and I just got my arduino i2c code to work, been working on it all day. All it does is the master reads the usb, then sends that data over the i2c bus, and the slave reads the data and if it is an ‘A’ then it lights up a led till more data comes through the lines. Enjoy: http://github.com/JoshAshby/i2c/tree/master