{c}
{tag=C (language)}

https://stackoverflow.com/questions/73877965/how-to-compile-c-c-code-into-a-hex-file-for-the-bbc-microbit

Official support is abysmal, very focused on <MicroPython> and their graphical UI.

The setup impossible to achieve as it requires setting up the <Yotta (Build system)>, just like the impossible to setup <Compile MicroPython code for Micro Bit locally on Ubuntu 22.04 with your own firmware> setup.

So we just use https://github.com/lancaster-university/microbit-samples + https://github.com/carlosperate/docker-microbit-toolchain[]:
``
docker pull ghcr.io/carlosperate/microbit-toolchain:latest
git clone https://github.com/lancaster-university/microbit-samples
cd microbit-samples
git checkout 285f9acfb54fce2381339164b6fe5c1a7ebd39d5

# Select a sample, builds one at a time. The default one is the hello world.
cp source/examples/hello-world/* source

# Build and flash.
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest yotta build
cp build/bbc-microbit-classic-gcc/source/microbit-samples-combined.hex "/media/$USER/MICROBIT/"
``
.hex file size for the hello world was 447 kB, much better than the <MicroPython> hello world downloaded from the website which was about 1.8 MB!

If you try it again for a second time from a clean tree, it fails with:
``
warning: github rate limit for anonymous requests exceeded: you must log in
``
presumably because after Yotta died it started using GitHub as a registry... sad. When will people learn. Apparently we were at 5000 API calls per hour. But if you don't clean the tree, you will be just fine.


Discussion on "Program the Micro Bit in C" by Ciro Santilli 32