firmware-ci-starter

A starting point for testing firmware in CI with LabWired, without hardware. Use this template and the first push already runs a firmware simulation in GitHub Actions.

What's in here

firmware/ is a small ARM Cortex-M0 program (firmware/src/main.c) that writes a greeting over UART and then loops. firmware/target/firmware is that program already built, so CI does not need a cross-compiler to run the test. tests/firmware-regression.yaml runs the firmware in LabWired's simulator for 20000 steps and checks that the UART output contains the greeting. .github/workflows/labwired.yml runs that test on every push and pull request using the labwired/firmware-test action.

Using this for your own firmware

Replace firmware/target/firmware with your own ELF, or point tests/firmware-regression.yaml at wherever your build puts it. Update the system field in the same file if your board isn't the generic Cortex-M0 used here. Change the uart_contains string to something your firmware actually prints, and add more assertions as needed — see the LabWired test script reference for what's available (register checks, memory checks, stop conditions, coverage).

If you rebuild the firmware in this repo, add a step to .github/workflows/labwired.yml that runs make -C firmware before the LabWired step, so CI always tests what your source currently produces rather than a stale binary. The tradeoff of committing a prebuilt ELF is exactly that: it can drift from the source if you forget to rebuild and recommit. For a real project, building in CI is usually worth the extra runner minutes.

What you get back

Pull requests get a comment with pass/fail status, step and cycle counts, and the UART output. Every run also gets a hosted report on labwired.com, and (for public repositories) shows up in the public gallery.

Rebuilding the firmware locally

cd firmware
make

Requires arm-none-eabi-gcc. main.c is a bare Cortex-M0 program: a two-entry vector table, a reset handler that calls main, and a UART driver that writes one register per character. LabWired's simulation is instruction-level and silicon-validated against real STM32 hardware, not an abstract model, so what passes here reflects how the instructions actually execute.