Manual Zephyr RTOS Installation on Windows

0. Introduction

Hello! This article is a step-by-step guide to a manual installation of Zephyr RTOS on Windows.

Zephyr is a modern open-source RTOS that is already used in industrial devices and IoT systems. It supports dozens of microcontrollers, including STM32 and ESP32-S3, and is ideal for those who want to go beyond Arduino and understand how a real-time system works.

Our goal is to create a fully controllable and isolated development environment.

1. Preparation — Downloading All The Necessary Components

In this section, let's download everything we need. We won't install anything, just download it.

Before diving into the world of Zephyr, we need to prepare our toolkit, such as Git and Python. If you already have them - perfect! If not, here are the links to download them.

1.1. Downloading the software

I will indicate the versions of the programs I use in parentheses, but yours may differ.

• Python (3.12.10): Programming language for Zephyr build scripts.

• Git (2.51.0): Version control system (required for west).

• 7-Zip (24.09): Archiver for unpacking the SDK.

• CMake (4.1.1): A powerful software build system.

• Ninja (1.13.1): A small build system with a focus on speed.

• OpenOCD (0.12.0): Debugger for microcontrollers.

• VS Code (1.105.0): Code editor with debugging support.

Don't let the list scare you — these are all standard, lightweight tools that will come in handy outside of Zephyr as well.

1.2. Download the Zephyr SDK

Zephyr SDK (0.17.4): Our set of compilers. Download the minimal SDK, only for STM32 and ESP32-S3, but feel free to download toolchains for any other microcontrollers you plan to work with.

The minimal SDK contains the basic infrastructure without all the compilers — we will add the necessary ones manually to save space and speed up the installation.

Navigate to the Zephyr page, locate the Zephyr SDK(Windows) installation section, and click on the Download the Zephyr SDK bundle link. This will take you to the official GitHub repository with the latest release.

Download three archives for Windows x86-64: Minimal, arm-zephyr-eabi, xtensa-espressif_esp32s3_zephyr-elf.

2. Setting Up The Sandbox Environment

2.1. Installing the main software

Install Python, Git, VS Code, 7-Zip, and CMake.

Important: When installing from the installer, make sure to check the "Add to PATH" box, if such an option is available, or manually add the paths to the executable files to the PATH variable.

2.2. Creating a folder structure

Let's create our Zephyr workshop. I will use D:\Zephyr, but you can choose any convenient location (for example, C:\Projects\Zephyr).

Go to the D:\Zephyr and create a folder called tools.

Unpack the contents of the Ninja and OpenOCD archives into tools, each into its own subfolder.

Next, from the zephyr-sdk-0.17.4_windows-x86_64_minimal.7z archive, unpack its contents into the tools folder.

A folder named zephyr-sdk-0.17.4 will appear inside tools, which we'll rename to zephyr-sdk for convenience.

Go to the zephyr-sdk folder and unpack the remaining two archives, toolchain_windows-x86_64_arm-zephyr-eabi.7z and toolchain_windows-x86_64_xtensa-espressif_esp32s3_zephyr-elf.7z, into it.

The folder structure should be as follows.

2.3 Creating a Python virtual environment

Open a terminal and check the Python installation and configuration:

> python --version

If you get a version number, everything is configured correctly.

Now let's create an isolated space for Zephyr Python scripts. This is called a virtual environment and is best practice to avoid library version conflicts. Open a terminal, navigate to D:\Zephyr, and run the command:

> python -m venv .venv

At this stage, you should have the .venv and tools folders.

2.4. Creating and activating a launcher script

Earlier, I mentioned that the paths to all executables need to be added to the PATH variable so that Windows knows where they are located, but this can be done locally via a batch file for the current session.

Instead of modifying the system's global environment variables, let's create a convenient zephyr-env.cmd script in the D:\Zephyr folder, which will configure our entire environment "on the fly".

The zephyr-env.cmd script will activate the Python virtual environment and set the variables ZEPHYR_BASE, ZEPHYR_SDK_INSTALL_DIR, ZEPHYR_TOOLCHAIN_VARIANT, and others only for the current terminal session.

You can add any environment variables to this script.

@echo off

REM Activate the Python virtual environment
call .venv\Scripts\activate.bat

REM Zephyr base folder
set BASE_DIR=D:\Zephyr

REM Variables for Zephyr
set ZEPHYR_BASE=%BASE_DIR%\zephyrproject\zephyr
set ZEPHYR_SDK_INSTALL_DIR=%BASE_DIR%\tools\zephyr-sdk
set ZEPHYR_TOOLCHAIN_VARIANT=zephyr

REM Paths to tools
set NINJA_DIR=%BASE_DIR%\tools\ninja
set OPENOCD_DIR=%BASE_DIR%\tools\openocd

REM Add everything to PATH
set PATH=^
%ZEPHYR_SDK_INSTALL_DIR%\arm-zephyr-eabi\bin;^
%ZEPHYR_SDK_INSTALL_DIR%\xtensa-espressif_esp32s3_zephyr-elf\bin;^
%NINJA_DIR%;^
%OPENOCD_DIR%\bin;^
%PATH%

REM Go to the desktop for convenience
cd /d %USERPROFILE%\Desktop

REM Open the command prompt
cmd

The folder structure should be as follows:

2.5. Checking the launcher script

Run zephyr-env.cmd. You should see the following in the terminal:

(.venv) C:\Users\Admin\Desktop>

Now let's make sure that all the tools are in place. Enter the following commands one by one. The response should be similar to the one below (versions may vary):

> git --version
> cmake --version
> openocd --version
> ninja --version
> arm-zephyr-eabi-gcc --version
> xtensa-espressif_esp32s3_zephyr-elf-gcc --version

If all commands show version numbers — great! The environment is set up correctly. If any command is not found, check the PATH and paths in the script.

2.6. Downloading Zephyr source code

Great, all the tools are in place! Now, staying in the same terminal (D:\Zephyr), let's install the Zephyr source code itself:

• Install west: This is Zephyr's "project manager". Install it in our virtual environment:

> pip install west

• Initialize the workspace: This command will create the main zephyrproject folder and download the Zephyr core into it:

> west init zephyrproject

• Download all modules: This command acts like an orchestrator, pulling in dozens of related projects (HAL modules, libraries, bootloaders) at their correct versions:

> cd zephyrproject
> west update

• Configure IDE integration: This allows CMake to automatically load boilerplate code required for building Zephyr applications:

> west zephyr-export

• Install Python dependencies: Now that we have all the source code, let's install the Python libraries needed to build it:

> west packages pip --install

• Download the binary files for Espressif: Final step — download the files required for Wi-Fi and Bluetooth to work on ESP32:

> west blobs fetch hal_espressif

The final folder structure should be as follows:

Important: Run zephyr-env.cmd each time you want to work with Zephyr RTOS.

3. Configuring Visual Studio Code

Our development environment is almost ready! All that's left is to configure VS Code for comfortable work with Zephyr.

3.1. Installing the Required Extensions

We'll install just four extensions that will make working with Zephyr as convenient as possible — from syntax highlighting to code autocompletion.

Launch VS Code and open the Extensions panel (Ctrl+Shift+X). In the Search Extensions field, enter the extension name and install it by clicking the Install button. Repeat this for all extensions shown in the image above.

3.2. Configuring CMake Tools

One extension left to configure — CMake Tools.

By default, it automatically configures the project every time you open or modify files. This creates a conflict with west, our Zephyr build system. Let's disable these automatic actions.

Open VS Code settings (File → Preferences → Settings or Ctrl+,).

In the Extensions → CMake Tools section, find and disable three options, as shown in the image.

Alternative for advanced users:

Open settings.json (Ctrl+Shift+P → "Open Settings JSON") and add these lines:

"cmake.configureOnOpen": false,
"cmake.configureOnEdit": false,
"cmake.automaticReconfigure": false,

Done! VS Code is configured and ready to work with Zephyr.

4. Conclusion

Congratulations! Now you don't just have Zephyr installed — you have your own fully controlled development lab for experimenting with microcontrollers.

Next Steps

Your development environment is ready for action. The best way to test it is by building a real project. Get started with one of our ready-to-use templates:

For STM32 BluePill: From Setup to Blinky: Your First Zephyr Project on STM32

For ESP32-S3 (N16R8): Zephyr on ESP32-S3: Your First 'Hello World'

To be continued!