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

Using software timers

Just like the name states, software timers are timers that are implemented with software. In MCUs, it is extremely common to have many different hardware peripheral timers available. These are often high resolution and have many different modes and features that are used to offload work from the CPU. However, there are two downsides to hardware timers:

  • Since they are part of the MCU, you'll need to create an abstraction above them to prevent your code from becoming tightly coupled to the underlying MCU hardware. Different MCUs will have slightly different implementations for timers. Because of this, it is easy for code to become dependent on the underlying hardware.
  • They will generally take more development time to set up than using the software-based timer that has already been provided by the RTOS.

Software timers alleviate this coupling by implementing...