Theses are some c codes I've been working with on raspberry pi pico, mainly on it's adc unit, and I will try more stuff in the future
To use it, you need to configure your raspberry pi pico c/c++ sdk, following the guides on: Pico c/c++ sdk, as well as their excellent official pdf: Getting Started with Pico.
To build the repo:
mkdir build
cd build
export PICO_SDK_PATH=../../pico-sdk
make -j4
Inside the build folder, there should be a src folder created that contains all the binary executable, just load the executable to raspberry pi pico and you're good to go!