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

Protecting Data and Synchronizing Tasks

What do race conditions, corrupt data, and missed real-time deadlines all have in common? Well, for one, they are all mistakes that can be easily made when operations are performed in parallel. These are also mistakes that are avoidable (in part) through using the right tools.

This chapter covers many of the mechanisms that are used to synchronize tasks and protect shared data. All the explanations in this chapter will contain example code and analysis that will have been performed using Ozone and SystemView.

First, we will explore the differences between semaphores and mutexes. Then, you will understand how, when, and why to use a semaphore. You'll also learn about race conditions and see how a mutex can avoid such situations. Example code will be provided throughout. The concept of race conditions will be introduced and fixed using...