This repository has one submodule (Unity unit testing framework) so when cloning make sure to include the --recurse-submodules
flag.
If the repo has already been cloned and the --recurse-submodules
flag was not included you can run git submodule update --init --recursive
mkdir -p _build
cd _build
cmake .. -G Ninja -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-gcc-toolchain.cmake
cmake --build .