`west` is the [Zephyr™ meta-tool](https://docs.zephyrproject.org/latest/guides/west/index.html) used to configure and build Zephyr™ applications. It can be installed by using the `pip` python package manager:
If you don't already have it configured, you may need to update your
`PATH` to include the pip install path. See [User Installs](https://pip.pypa.io/en/stable/user_guide/#user-installs) and (Stack Overflow)[https://stackoverflow.com/questions/38112756/how-do-i-access-packages-installed-by-pip-user] for more details.
The installation will prompt with several questions about installation location, and creating a default `~/.zephyrrc` for you with various variables. The defaults shouldn normally work as expected.
an onboard MCU, or one that uses a MCU board addon.
### Keyboard (Shield) + MCU Board
ZMK treats keyboards that take a MCU addon board as [shields](https://docs.zephyrproject.org/latest/guides/porting/shields.html), and treats the smaller MCU board as the true [board](https://docs.zephyrproject.org/latest/guides/porting/board_porting.html)
Given the following:
- MCU Board: Proton-C
- Keyboard PCB: kyria
- Keymap: default
You can build ZMK with the following:
```bash
west build -b proton_c -- -DSHIELD=kyria -DKEYMAP=default
Keyboards with onboard MCU chips are simply treated as the [board](https://docs.zephyrproject.org/latest/guides/porting/board_porting.html) as far as Zephyr™ is concerned.