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

Comparing RTOS tasks to super loops

So far, we've only mentioned tasks very casually, but what is a task, really? An easy way to think about a task is that it is just another main loop. In a preemptive RTOS, there are two main differences between tasks and super loops:

  • Each task receives its own private stack. Unlike a super loop in main, which was sharing the system stack, tasks receive their own stack that no other task in the system will use. This allows each task to have its own call stack without interfering with other tasks.
  • Each task has a priority assigned to it. This priority allows the scheduler to make decisions on which task should be running (the goal is to make sure the highest priority task in the system is always doing useful work).

Given these two features, each task may be programmed as if it is the only thing the processor has to do. Do you have a single...