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

Stream buffers (FreeRTOS 10+)

Stream buffers combine the convenience of a queue-based system with the speed closer to that of the raw buffer implementations we created previously. They have some flexibility limitations that are similar to the limitations of task notification systems compared to semaphores. Stream buffers can only be used by one sender and one receiver at a time. Otherwise, they'll need external protection (such as a mutex), if they are to be used by multiple tasks.

The programming model for stream buffers is very similar to queues, except that instead of functions being limited to queueing one item at a time, they can queue multiple items at a time (which saves considerable CPU time when queuing blocks of data). In this example, we'll explore stream buffers through an efficient DMA-based circular buffer implementation for UART reception.

The goals of...