I’ve been working on this project on and off (mostly off) for a few months now. My AVR skills were a little rusty getting into this so I’ll use that as an excuse for not making more progress.

I’ve done a fair bit of research on the Apple Desktop Bus (ADB) protocol and I’ll share what I’ve found out in another post. My friends Chris and Ben and I did a fair bit of work on an AVR USB implementation so that side of things doesn’t seem as daunting to me. I’ve looked at different AVR microcontrollers and right now the AT90USB168 seems like a good fit for what I need.

The wall I’ve run into recently is that the keyboard doesn’t appear to be responding to commands like it used to. I don’t know if I’ve fried it while doing work—ADB is not hot-pluggable—or if my timing is off, or what. I’ve opened an issue in GitHub to track it. I also printed some PCBs to probe the bus while the keyboard is plugged into the old Mac to see if it works then. Photos soon!