Getting Started with Zephyr on STM32: A Complete Guide

Introduction:

Zephyr is a lightweight, real-time operating system (RTOS) designed for resource-constrained devices, and STM32 microcontrollers are widely used in embedded systems. This guide will walk you through the process of setting up and running Zephyr OS on an STM32 development board. Whether you're just starting or need a quick setup, this blog has you covered.

Prerequisites:

1. STM32 Development Board: Any STM32 board should work, but for simplicity, this guide will use the STM32 Nucleo board.
2. Zephyr SDK: Zephyr needs its development tools to be installed.
3. CMake: Required for building Zephyr projects.
4. GNU ARM Toolchain: This is required for compiling code for STM32.
5. Python: To use Zephyr’s tools, Python 3.x is required.
6. JLink Debugger (Optional but recommended): If you're using J-Link for debugging, this will come in handy.

Steps for zephyr environment:

Step 1: Setting Up Zephyr Environment

1. Install Zephyr SDK: The Zephyr SDK can be installed on Windows using the official guide from the Zephyr documentation. Download and install the SDK by following the steps listed on Zephyr Getting Started.

2. Install CMake and Ninja Build: Download CMake and Ninja from their official websites and install them.

   • CMake Download
   • Ninja Download

3. Install Python: Download and install Python 3.x from the official Python website.

4. Install GNU ARM Toolchain: Download the ARM GCC toolchain from Arm Developer. Follow the instructions to add it to your system's PATH.

Step 2: Set Up Zephyr Environment on Windows

1.Clone Zephyr Repository: Open PowerShell or Command Prompt and clone the Zephyr repository using Git:

git clone https://github.com/zephyrproject-rtos/zephyr.git
cd zephyr

2.Install West: Zephyr uses the

west

west

pip install west

3.Install Zephyr Dependencies: Run the following command to initialize the Zephyr workspace:

west init
west update

4.Source Zephyr Environment: To set up the environment, you need to source the Zephyr environment variables. On Windows, use:

.\zephyr\scripts\env\windows\zephyr-env.bat

This will set the necessary environment variables to use Zephyr.

Step 3: Configure STM32 Board

1.Choose STM32 Board: Zephyr supports a range of STM32 boards. This example will use the STM32 Nucleo-64 (F401RE) board. To specify the board for your project, set the

BOARD

set BOARD=nucleo_f401re

2.Prepare Your Application: You can use Zephyr's sample applications to test your setup. For this guide, let's use the blinky example:

west build -b nucleo_f401re samples/basic/blinky

3.Configure the Project: The build system will automatically configure the project for the STM32 Nucleo board. Ensure the board is connected to your PC via USB or a debugger.

Step 4: Build and Flash the Application

1.Build the Application: To compile the project, run the following command:

west build -b nucleo_f401re

This will compile the blinky application for your STM32 board.

2.Flash the Application: Flash the compiled application onto the STM32 board. You can use a J-Link or ST-link debugger or OpenOCD to do this. The flashing command is as follows:

• Using J-Link: First, ensure that your J-Link debugger is connected to the STM32 board. Then, use the following command:

west flash

• Using ST-Link: First, ensure that your ST-Link debugger is connected to the STM32 board. Then, use the following command:

west flash

• Using OpenOCD (if you're using OpenOCD instead of J-Link):

openocd -f board/nucleo_f401re.cfg -c "program build/zephyr/zephyr.bin verify reset exit"

Step 5: Debug and Monitor the Application

1.Debugging: Zephyr provides a GDB interface for debugging. To start a GDB session, use:

west debug

2.Monitoring: To monitor the application's output or system logs, use:

west monitor