Kicking the CAN #3 — Message Service

2026-03-05

What I didn't know at the time, and what Claude hadn't told me: loopback is executed exclusively locally on the controller and transceiver. The bus itself, i.e. CAN_H and CAN_L, is completely untouched by it.

Full of enthusiasm, assuming I had built a CAN bus system without any fundamental knowledge of CAN, I instructed Claude Code to take the next step.

The RPi4 was supposed to act as sender, transmitting a counter value, and the STM32 was supposed to toggle the LED every time it received a message.

A few minutes later, Claude Code reported completion in both projects and ..... NOTHING blinked .... for an entire afternoon.