LiPo batteries are great for drones but you don't want to over discharge them. To allow our Flight Controller to monitor battery capacity we used a non blocking scheduler and packaged our requirements up as an Arduino Library, NexgenTimer.
Our library is an amalgamation of the MillisTimer and ElapsedTimer libraries with some application specific examples and an extra Timeout class. It only uses functions from the Arduino core API and hence should work on all Arduino boards.
It can be downloaded using the Arduino Library Manager and you can read all about it in our latest article on Medium - https://reefwing.medium.com/how-to-write-your-own-flight-controller-software-part-6-7ce0fa3e8008
