Open firmware for USB to CAN adapters

ferrocan is gs_usb firmware in Rust for STM32-based adapters. It speaks the protocol of candleLight and Linux's gs_usb driver, so SocketCAN works with it out of the box.

Adapters

What it does

• Echoes a frame once it's on the bus: acknowledged, not merely queued, and in bus order with the frames received.
• Reports the bus as candleLight does: error warning, error passive, bus-off and its automatic restart, with the error counters, and each bus error when asked.
• Starts clean: every session begins as from power-on, with no frames or counts left from the last.
• Reflashes without opening the case: the host can restart it in ST's ROM bootloader over USB.
• Tells a host why a frame wasn't sent, for hosts that ask (an extension Linux doesn't use): given up, bus-off, aborted, lost arbitration or an error; and can withdraw a pending frame.

Installing it

In Chrome or Edge, flash it from this site: plug the adapter in, pick it, and the flasher restarts it in its bootloader, saves the firmware it had, writes ferrocan, checks it and starts it.

Elsewhere, use dfu-util and the images of a release; the repository's scripts/flash.sh does the same steps.

Checking an image

Each release lists the SHA-256 of every file, and its images carry signed build provenance from GitHub Actions:

gh attestation verify ferrocan-0.1.0-sh-c30.bin -R ferrocan/ferrocan

The images are reproducible: scripts/release.sh, with the toolchain and dependencies the repository pins, builds the same bytes on any machine.