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

RTOS queues

Queues are quite simple in concept, but they are also extremely powerful and flexible, especially if you've traditionally programmed on bare metal with C. At its heart, a queue is simply a circular buffer. However, this buffer contains some very special properties, such as native multi-thread safety, the flexibility for each queue to hold any type of data, and waking up other tasks that are waiting on an item to appear in the queue. By default, data is stored in queues using First In First Out (FIFO) ordering – the first item to be put into the queue is the first item to be removed from the queue.

We'll start by taking a look at some simple behavior of queues when they are in different states and used in different ways (sending versus receiving) and then move on to how queues can be used to pass information between tasks.