Custom expansion board

[Mohammad]

Hello,

I am thinking of using a custom board that connects to Duet 3 Mainboard 6HC via CAN, sending and receiving messages over CAN. I was wondering if this is doable and if there are any suggestions/recommendations about this as I am new here.
The goal is that I send a code (let's say M1000) to the Mainboard and that causes a specific message to be sent to my custom board through CAN and vice-versa.

I have already looked through the RepRapFirmware source code a little and can tell I probably need to add the code(s) handling to GCodes2.cpp; However, I am unsure of how the communication between the main board and the custom board would have to be setup.

I appreciate any help on what things I would need to modify in the RepRapFirmware to achieve this or where I should start from.

Best Regards,
Mohammad

[dc42]

@Mohammad how much data do you need to pass to your custom board? It may be that you could use an existing message; for example, if you just need to pass a small integer (e.g. a port number) and a float then you could use CanMessageWriteGpio. Then you could also access the device using M950 and M42.

A possible starting point for your custom board is the SAMMYC21 development board. We provide a sample firmware build for that board.

[Mohammad]

@dc42 Thank you for the guidance. I was able to find answers to lots of questions by looking at the sample firmware you mentioned.