CncAtc is an Arduino program for connecting an AMB 1050 FME-W DI tool-changing spindle to a GRBL CNC controller. This is one of the cheapest ways to create a working tool-changing CNC machine.
As it exists, this code is tightly tied to my machine, and is probably of limited use to most people directly, but may be useful as an example. It doesn't currently make any attempt at being modular or runtime-configurable. It wasn't really written as an open source project, it was written to solve a problem for me, and it shows evidence of multiple false starts and abandoned approaches.
I'm releasing it because multiple people have asked me for a copy, and it's reasonably readable as-is. Unneeded features like current monitoring and air pressure monitoring can be easily removed (or just ignored), and the core is decent enough. If there's interest, then I can work on making it more generically useful over time.
This is not an officially supported Google product.