Firmware — building and flashing¶

The project pins two git submodules:

firmware/third_party/pico-sdk at tag 2.2.0 (commit a1438df).
firmware/third_party/can2040 at commit 2988d4f (v1.7.0-8).

The pico-sdk itself carries nested submodules (TinyUSB 0.18.0, lwIP, mbedtls, pico-cmake-utils). Always init recursively on the outer call:

git submodule update --init --recursive firmware/third_party/pico-sdk \
                                        firmware/third_party/can2040

cmake -S firmware -B firmware/build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build firmware/build --parallel

Artefacts land in firmware/build/:

File	Purpose
`rpbridge.uf2`	Mass-storage drag-and-drop target for the BOOTSEL bootloader.
`rpbridge.elf`	With debug info; for `gdb`, SEGGER, picoprobe.
`rpbridge.bin`	Raw flash image, useful with external programmers.
`rpbridge.hex`	Intel HEX, for factory programmers.
`rpbridge.dis`	Disassembly listing (release builds only).
`size.txt`	`arm-none-eabi-size` summary.

Flash options¶

Method	Command
BOOTSEL mass-storage	Copy `.uf2` to the `RPI-RP2` volume.
`picotool`	`picotool load -fxv firmware/build/rpbridge.uf2`
From userspace CLI	`rpbridge-ctl flash firmware/build/rpbridge.uf2`
SWD debugger (picoprobe, J-Link)	`openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "program rpbridge.elf verify reset exit"`

Cross-platform¶

The build works on Linux, macOS and Windows (WSL recommended on Windows). Toolchain is the same on every host — arm-none-eabi-gcc plus CMake and Ninja.