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)
1
Section 1: Introduction and RTOS Concepts
5
Section 2: Toolchain Setup
9
Section 3: RTOS Application Examples
13
Section 4: Advanced RTOS Techniques

RTOS mutexes

The term mutex is shorthand for mutual exclusion. In the context of shared resources and tasks, mutual exclusion means that, if a task is using a shared resource, then that task is the only task that is permitted to use the resource all others will need to wait.

If all this sounds a lot like a binary semaphore, that's because it is. However, it has an additional feature that we'll cover soon. First, let's take a look at the problem with using a binary semaphore to provide mutual exclusion.

Priority inversion

Let's look at a common problem that occurs when attempting to use a binary semaphore to provide mutual exclusion functionality.

Consider three tasks, A, B, and C, where A has the...