Introduction to Zephyr Part 6: How to Write a Device Driver | DigiKey

We delve into the essentials of writing a custom device driver in the Zephyr RTOS by building a simple “button” driver. You’ll learn the importance of having a driver that acts as a bridge between your hardware and the operating system, making it possible to reliably read button states across different embedded platforms. Shawn is hosting a free, hands-on webinar that walks you through the process of developing your own device driver in Zephyr. Check it out! https://event.on24.com/wcc/r/4870160/... You can find a written version of this tutorial here: https://www.digikey.com/en/maker/tuto... The GitHub repository for this course (including solutions to the challenges) can be found here: https://github.com/ShawnHymel/introdu... The MCP9808 I2C driver solution (and walkthrough) can be found here: https://github.com/ShawnHymel/worksho... We start with the core driver implementation: button.c and button.h, explaining how to initialize the GPIO pin as input and retrieve button state. We also underscore the significance of logging and error-handling to help you quickly diagnose issues in real-world embedded scenarios. You’ll see how the Devicetree macros automatically generate multiple instances of the driver for each “custom,button” node—an invaluable feature when managing multiple buttons or sensors. This section shows how each driver instance is set up with its own configuration struct, ensuring that every hardware component is correctly identified and initialized. Next, we examine the file structure for our driver, highlighting the roles of each CMakeLists.txt, Kconfig, and source file. This organized approach clarifies how Zephyr’s modular build system integrates driver code, enabling a portable and scalable setup for development teams working on diverse targets. We then demonstrate how to test the driver using an application-level file structure, with a dedicated main.c, prj.conf, and an overlay file for board-specific pin overrides. By combining these elements, you’ll see how to assemble a complete project that initializes, reads, and confirms button input behavior in a real-world development environment. Whether you’re new to embedded development or looking to refine your Zephyr RTOS skills, this guide provides a practical roadmap to building reliable device drivers. With clear file structure explanations, Devicetree insights, and testing methodology, you’ll have the confidence to expand your embedded software projects and tailor them to any hardware platform. Official Zephyr documentation: https://docs.zephyrproject.org/latest... Introduction to RTOS:    • Introduction to RTOS Part 1 - What is a Re...   ESP32-S3-DevKitC: https://www.digikey.com/en/products/d... Maker.io - https://www.digikey.com/en/maker DigiKey’s Blog – TheCircuit https://www.digikey.com/en/blog Connect with DigiKey on Facebook   / digikey.electronics   And follow us on X: https://x.com/digikey 00:00 Intro 1:05 Hardware Overview 1:21 Custom Driver C Code 25:11 Custom Driver CMake Files 28:36 Custom Driver Kconfig Files 30:46 Custom Driver Binding File 35:10 Custom Driver Module File 37:40 Demo Application 55:08 Custom Driver Instancing Demo 56:27 Challenge: MCP9808 I2C Temperature Sensor Driver 58:33 Conclusion