CAN Configuration Interface

tools/scripts/config.py pushes a device’s settings to a board over CAN. This is how a board is commissioned after it has been flashed.

Prerequisites

A CAN interface must be up. With an mjbots FDCANUSB:

sudo ./scripts/fdcanusb.sh --net can0

You also need the board’s current CAN ID. A freshly flashed board has whatever its firmware defaults to, not the ID in the file you are about to send.

Usage

uv run --project tools python tools/scripts/config.py \
    --definition config/abs.yaml \
    --file rover/ra/abs_de_pitch.yaml \
    --can can0 \
    --id 55

Caution

On new MCUs, the flash defaults high, so the address of a new device will be 0xFF, or 255.

Flag	Required	Meaning
--definition, -d	yes	the board’s register layout, from config/
--file, -f	yes	the device’s values, from rover/
--can, -c	yes	CAN interface name, e.g. can0
--id, -i	yes	the board’s current CAN ID
--read, -r	no	read config back from the device

Caution

--read is not implemented. The flag parses and the tool runs, but the read branch is an empty stub, so it reports success without having read anything.

Sent Configuration Frames

1. Parses the definition to work out each register’s address, type and bit layout.
2. Reads the device file and packs its values into register-sized integers. Floats are reinterpreted as their IEEE-754 bit pattern.
3. Prints the resulting register table so you can check it before it goes out.
4. Sends one ESWConfigCmd frame per register, addressed to --id, with a 100 ms gap between frames.

Each frame carries three signals:

Signal	Width	Meaning
address	8 bits	register address
value	32 bits	raw value
apply	1 bit	commit the write

Processing Configuration Frames

Firmware handles ESWConfigCmd by calling set_raw(address, value) on its config struct. That finds the register at that address, writes it, and persists the change: the last flash page is read into RAM, patched, erased and reprogrammed.

Because each register is a separate frame and each write rewrites the flash page, configuration is not atomic. A board interrupted partway through has some new values and some old ones. Re-run the tool rather than assuming it took.

Changing a Board’s CAN ID

can_id is itself a register, so changing it is an ordinary write, but the board stops answering on the old ID the moment it lands. Use the new ID for anything afterwards, and if the run fails partway through, retry with whichever ID actually took.