Hi! I may not be able to give a very concise and accurate answer on this, as I did it many years ago and don’t remember it very well. I will try to do the best I can-
The home cycle is a function of GRBL that I just tuned to work with Thor. In the firmware file config.h (lines 75 to 79) I added the homming sequence. The firmware file motion_control.c calls a function called limits_go_home that appears to be in charge of the homming process. And sadly that’s all I can remember :S
About the second comment, I may be wrong but I guess that when I was tunning the configuration file, I wrote the BIT and the digital pin of each sensor associated with its motor. As the motor C uses the same homming sensor as the motor B (as they both power the articulation 2) I copied the configuration of the B motor on the C one and I left the previous comment just in case I would need to locate the sensor’s pins. Same goes for the G motor.
Hope it helps! 😉