Building custom bootloader

[cadenhillis]

Hey,

I'm coding some custom firmware for a version of pycubed with an N20 SAMD51 instead of the regular J19 / 20's and have built the circuitpython firmware fine.

I can't see any resources to build a revised bootloader, do you know of any documentation on how to do this?

Thanks! :)

[maholli]

Hey @cadenhillis ,

Glad to hear you were successful building custom circuitpython!

As for the UF2 bootloader, I don't expect that to give you much trouble. Use this uf2-samd repo and add a directory to uf2-samdx1/boards/. You can reference the PyCubed bootloader build definitions.

Let me know how it goes

[cadenhillis]

Hey @maholli,
Thanks! I was just missing that information. Built the bootloader successfully :) Should be debugging our version of the boards in a week or two.

[maholli]

Awesome! Nice work. make sure to post pics :)

[polygnomial]

For posterity, I've had a trouble with the wrong version of arm-none-eabi toolchain compiling UF2 bootloaders that don't work. Usually works with a recent (ish) version of the GNU Arm toolchain. I tried in late-february with 11.2-2022.02 (released 2/15/2022) and that didn't work, and neither did whatever version 7 I had before updating. I'm currently using 10.3-2021.07 which hasn't given me any problems so far.

[cadenhillis]

I successfully built it with the 10-2020-q4-major release with no problems. :)