Ardupilot code reading


I have recently downloaded the ardupilot repository and have taken a quick look around its cpp files. I do realize understanding someone else’s code is a hard task, so I wanted to know if you guys would have any suggestions on where to start reading/following it. For starters, is there a main?

I currently have a Navio2+RPi 2 system. I am mostly interested in:

  1. Printing sensor data to the screen (gps and imu).
  2. Saving data to sd card. Or another easy-access folder for data ploting.
  3. Receiving input from external xbee.
  4. Understanding how the motors receive their throttle input and what part of the code takes care of that.

Thank you,

It’s a lot of code… but the dev guide here: is really useful