While there are a couple of open-source brushless drivers already available, [neuromancer2701] created his own brushless motor controller on an Arduino shield.

I recently had to build an infrared close proximity sensor that could tell if something was dropped in a parcel delivery drop box. After some searching, I ...

The full write-up is in the included PDF file, and describes the set-up of an Arduino Nano sitting between throttle and controller, and taking feedback from a current sensor.