Modules (External projects)

To be classified as a candidate for being included in the default list of modules, an external project is required to have its own life-cycle outside the Zephyr Project, that is, reside in its own repository, and have its own contribution and maintenance workflow and release process. This is why this project aims to create the Ardiuno Core API as a zephyr module.

Integrate modules in Zephyr build system

The build system variable ZEPHYR_MODULES is a CMake list of absolute paths to the directories containing Zephyr modules. These modules contain CMakeLists.txt and Kconfig files describing how to build and configure them, respectively. Module CMakeLists.txt files are added to the build using CMake’s add_subdirectory() command, and the Kconfig files are included in the build’s Kconfig menu tree.

You can add additional modules to this list by setting the ZEPHYR_EXTRA_MODULES CMake variable or by adding a ZEPHYR_EXTRA_MODULES line to .zephyrrc. This can also be given with -DZEPHYR_EXTRA_MODULES=/<path>/foo then the module given by the command line variable ZEPHYR_EXTRA_MODULES will take precedence. This allows you to use a custom version of FOO when building and still use other Zephyr modules provided by west. This can for example be useful for special test purposes.

Module yaml file description

A module can be described using a file named zephyr/module.yml. The format of zephyr/module.yml is described in the following:

Compiling my custom module

I created a custom module called Arduino-Core-Zephyr . The structure of this module looks like:

.
├── CMakeLists.txt
├── cores
│   ├── arduino
│   └── CMakeLists.txt
├── examples
│   └── hello_world
├── Kconfig
├── README.md
└── zephyr
    └── module.yml

To make sure zephyr uses it while building, we use the following command: west build -p -b qemu_x86 samples/hello_world -DZEPHYR_EXTRA_MODULES=/home/dhruva/zephyrproject/modules/lib/Arduino-Core-Zephyr