CAN Protocol Reference

Appendix status: Initial reference

This table mirrors the protocol decisions currently recorded in the repository. The source code remains authoritative until automated protocol-table generation is introduced.

Identifier categories

Priority	Category	Range	Direction	Nominal timing
0	Error	0x000-0x0FF	STM32 to RPi	Event driven
1	Velocity command	0x100	RPi to STM32	50-100 ms
2	Encoder/range feedback	0x200-0x202	STM32 to RPi	20 ms control cycle
3	Heartbeat	0x300	RPi to STM32	100 ms
4	PID tuning	0x400-0x402	RPi to STM32	Event driven
5	ACK/response	0x500-0x5FF	STM32 to RPi	Event driven

All multibyte numeric payloads are little-endian. The heartbeat timeout is 200 ms and must gate the entire motor-control update.

Motor index contract

Motor commands use 0=FL, 1=FR, 2=RL, 3=RR. Encoder wiring is a separate physical mapping: the current rear encoder channels are swapped, so estimation maps encoder index 2 to rear-right and index 3 to rear-left. See Failure: the rear encoder channels were swapped before changing either mapping.

Sources

• protocol.py

• main.c