Getting Started with Zephyr RTOS: A Practical Guide for Beginners

Zephyr RTOS

Real-time operating systems (RTOS) are essential in embedded systems, and Zephyr RTOS has emerged as a powerful, open-source option. Zephyr is a feature-rich, scalable RTOS that supports multiple architectures and integrates with modern development tools.

This article provides a practical guide for beginners, focusing on setting up Zephyr on Windows Subsystem for Linux (WSL), flashing a simple "blinky" program, and understanding how Zephyr differs from FreeRTOS. Key aspects such as Kconfig, device tree, and build system will also be covered.

Why Choose Zephyr RTOS?

Zephyr RTOS is designed for embedded applications requiring low power, security, and scalability. It offers:

? Multi-architecture support – Works on ARM, x86, RISC-V, and more.

? Modular kernel – Enables fine-grained control over system features.

? Device Tree and Kconfig system – Provides hardware and software configuration flexibility.

? Built-in networking and security – Ideal for IoT applications.

? Active open-source community – Supported by the Linux Foundation.

Setting Up Zephyr RTOS on WSL

I recently set up Zephyr on WSL (Windows Subsystem for Linux) and flashed a simple blinky program. Here’s how you can do it step-by-step.

1. Install Dependencies

First, ensure you have WSL2 with Ubuntu installed. Open WSL and run the following commands:

sudo apt update && sudo apt upgrade -y
sudo apt install --no-install-recommends cmake ninja-build gperf ccache \
    dfu-util device-tree-compiler wget \
    python3-pip python3-setuptools python3-wheel python3-dev \
    git
        

2. Install West (Zephyr’s Meta Tool)

West is the official tool for managing Zephyr repositories and building projects. Install it with:

pip3 install --user west
        

3. Clone and Initialize Zephyr Project

mkdir ~/zephyrproject && cd ~/zephyrproject
west init
west update
west zephyr-export
        

4. Install Toolchain

For ARM-based boards (like STM32 or Nordic), install the Zephyr SDK:

wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.16.4/zephyr-sdk-0.16.4_linux-x86_64.tar.gz
tar xvf zephyr-sdk-0.16.4_linux-x86_64.tar.gz
cd zephyr-sdk-0.16.4
./setup.sh
        

Alternatively, use arm-none-eabi-gcc if you already have it.

5. Build and Flash a Blinky Program

Now, let’s compile and flash a simple LED blink program.

cd ~/zephyrproject/zephyr
west build -b nucleo_f446re samples/basic/blinky
west flash
        

If you're using a different board, replace nucleo_f44re with your board's name.

How Zephyr RTOS Differs from FreeRTOS?

FeatureZephyr RTOSFreeRTOSArchitectureModular, scalable, supports multiple architecturesPrimarily ARM Cortex-MSchedulingPreemptive, cooperativePreemptive, cooperativeConfigurationUses Kconfig and Device TreeUses header files and configuration macrosDrivers & HALBuilt-in driver model, supports multiple vendorsNo standard driver modelSecurityMemory protection, access controlBasic security featuresCommunityBacked by the Linux FoundationMaintained by AWS

Zephyr offers better modularity, standardization, and security compared to FreeRTOS, which is simpler and widely used in industrial applications.

Understanding Kconfig, Device Tree, and Build System

1. Kconfig (Kernel Configuration System)

Zephyr uses Kconfig, similar to the Linux kernel, for feature selection. It allows users to enable or disable kernel features, drivers, and subsystems.

To configure Zephyr manually, use:

west build -t menuconfig
        

This brings up an interactive menu to tweak kernel settings.

Example: Enabling UART logging

CONFIG_LOG=y
CONFIG_UART_CONSOLE=y
        

2. Device Tree (DT)

Zephyr uses Device Tree (DT) to describe hardware configurations instead of hardcoded drivers.

Example: Enabling an LED

led0: led_0 {
    gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
    label = "User LED";
};
        

Each board has a .dts file that defines hardware components.

3. Build System (CMake & Ninja)

Zephyr’s build system is CMake-based with Ninja as the default build tool.

A typical Zephyr project contains:

• CMakeLists.txt – Project configuration

• prj.conf – Kconfig settings

• .dts files – Hardware description

To build a custom project, modify prj.conf and CMakeLists.txt, then use:

west build -b your_board .
        

Final Thoughts

Zephyr RTOS is an excellent choice for modern embedded systems, providing scalability, security, and ease of configuration. While FreeRTOS is simpler, Zephyr’s Kconfig, Device Tree, and modular build system make it highly adaptable.

If you’re coming from FreeRTOS, Zephyr might seem complex initially, but once you understand Kconfig, Device Tree, and its build system, it becomes a powerful tool for embedded development.

Next Steps:

? Try modifying the blinky program.

? Explore Kconfig and Device Tree settings.

? Experiment with different hardware peripherals.

Let me know if you want to dive deeper into any aspect of Zephyr RTOS!