Book Image

Hands-On RTOS with Microcontrollers

By : Brian Amos
Book Image

Hands-On RTOS with Microcontrollers

By: Brian Amos

Overview of this book

A real-time operating system (RTOS) is used to develop systems that respond to events within strict timelines. Real-time embedded systems have applications in various industries, from automotive and aerospace through to laboratory test equipment and consumer electronics. These systems provide consistent and reliable timing and are designed to run without intervention for years. This microcontrollers book starts by introducing you to the concept of RTOS and compares some other alternative methods for achieving real-time performance. Once you've understood the fundamentals, such as tasks, queues, mutexes, and semaphores, you'll learn what to look for when selecting a microcontroller and development environment. By working through examples that use an STM32F7 Nucleo board, the STM32CubeIDE, and SEGGER debug tools, including SEGGER J-Link, Ozone, and SystemView, you'll gain an understanding of preemptive scheduling policies and task communication. The book will then help you develop highly efficient low-level drivers and analyze their real-time performance and CPU utilization. Finally, you'll cover tips for troubleshooting and be able to take your new-found skills to the next level. By the end of this book, you'll have built on your embedded system skills and will be able to create real-time systems using microcontrollers and FreeRTOS.
Table of Contents (24 chapters)
Section 1: Introduction and RTOS Concepts
Section 2: Toolchain Setup
Section 3: RTOS Application Examples
Section 4: Advanced RTOS Techniques

Creating a command queue

To see how a queue can be used to keep an architecture loosely coupled, we'll take a look at an application that accepts commands over USB and lights LEDs. While the example application itself is very simple, the concepts presented here scale extremely well. So, regardless of whether there are only a few commands or hundreds, the same approach can be used to keep the architecture flexible.

This application also shows another example of how to keep higher-level code loosely coupled to the underlying hardware. It ensures the LED command code only uses a defined interface to access a Pulse Width Modulation (PWM) implementation, rather than directly interacting with the MCU registers/HAL. The architecture consists of the following major components:

  • A USB driver: This is the same USB stack that has been used in previous examples. VirtualCommDriverMultiTask...