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 FreeRTOS heap implementations

Because FreeRTOS targets such a wide range of MCUs and applications, it ships with five different dynamic allocation schemes, all of which are implemented with a heap. The different heap implementations allow different levels of heap functionality. They are included in the portable/MemMang directory as heap_1.c, heap_2.c, heap_3.c, heap_4.c, and heap_5.c.

A note on memory pools:

Many other RTOSes include memory pools as an implementation for dynamic memory allocation. A memory pool achieves dynamic allocation by only allocating and freeing fixed-size blocks. By fixing the block size, the problem of fragmentation is avoided in memory-constrained environments.

The downside to memory pools is that the blocks need to be sized for each specific application. If they are too large, they will waste precious RAM; too small, and they'll be unable...