zephyr

Zephyr RTOS

Purpose

Guide agents through Zephyr application development: west build workflow, board configuration, Kconfig and devicetree, Zephyr shell and logging, native_sim target for host testing, and debugging with GDB.

Triggers

• "How do I build a Zephyr application with west?"
• "How do I configure Zephyr with Kconfig?"
• "How do I use devicetree overlays in Zephyr?"
• "How do I add logging to my Zephyr application?"
• "How do I run Zephyr on my host machine for testing?"
• "How do I debug a Zephyr application?"

Workflow

1. Workspace setup and first build

# Install west
pip install west

# Initialize workspace from Zephyr manifest
west init ~/zephyrproject
cd ~/zephyrproject
west update                          # fetches Zephyr + all modules

# Install Python dependencies
pip install -r ~/zephyrproject/zephyr/scripts/requirements.txt

# Install Zephyr SDK (toolchains for all targets)
# Download from: https://github.com/zephyrproject-rtos/sdk-ng/releases
export ZEPHYR_SDK_INSTALL_DIR=~/zephyr-sdk-0.17.0
export ZEPHYR_BASE=~/zephyrproject/zephyr

# Build hello_world for a target board
west build -b nrf52840dk/nrf52840 samples/hello_world

# Flash to hardware
west flash

# Open serial monitor
west espressif monitor  # or: screen /dev/ttyACM0 115200

Common board targets:

Board	Target name
nRF52840 DK	nrf52840dk/nrf52840
STM32 Nucleo-F446RE	nucleo_f446re
Raspberry Pi Pico	rpi_pico/rp2040
ESP32	esp32_devkitc_wroom/esp32/procpu
QEMU Cortex-M3	qemu_cortex_m3
Native POSIX	native_sim

2. Application structure

my_app/
├── CMakeLists.txt
├── prj.conf              # Kconfig fragment
├── app.overlay           # devicetree overlay (optional)
└── src/
    └── main.c

# CMakeLists.txt
cmake_minimum_required(VERSION 3.20.0)
find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
project(my_app)
target_sources(app PRIVATE src/main.c)

3. Kconfig — feature configuration