Re-upload of a dusty Multiwii Serial Protocol implementation found in Google Code. This was supposedly an implementation of Multiwii Serial Protocol, which can still be used for Betaflight etc. flight controllers, with the main advantage being the ability to ask for detailed telemetry (such as IMU data and aircraft orientation) from the flight controller.
An archived overview of MSP can be found here: https://web.archive.org/web/20200225114200/http://www.multiwii.com/wiki/index.php?title=Multiwii_Serial_Protocol