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

Creating a polled UART driver

When writing low-level drivers, it's a must to read through the datasheet in order to understand how the peripheral works. Even if you're not writing a low-level driver from scratch, it is always a good idea to gain some familiarity with the hardware you'll be working with. The more familiarity you have, the easier it will be to diagnose unexpected behavior, as well as to create efficient solutions.

You can read more about the UART peripheral we're working with in Chapter 34 of the STM RM0410 STM32F76xxx reference manual (USART).

Our first driver will take an extremely simple approach to getting data from the UART and into a queue that can be easily monitored and consumed by any task in the system. By monitoring the receive not empty ( RXNE) bit of the UART peripheral's interrupt status register (ISR), the driver can determine...