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

Introducing the UART

As we briefly covered in Chapter 4, Selecting the Right MCU, the acronym UART stands for Universal Asynchronous Receiver/Transmitter. UART hardware takes bytes of data and transmits them over a wire by modulating the voltage of a signal line at a predetermined rate:

The asynchronous nature of a UART means no additional clock line is needed to monitor individual bit transitions. Instead, the hardware is set up to transition each bit at a specific frequency (baud rate). The UART hardware also adds some extra framing to the beginning and end of each packet it transmits. Start and stop bits signal the beginning and end of a packet. These bits (along with an optional parity bit) are used by the hardware to help guarantee the validity of packets (which are typically 8 bits long).

A more general form of UART hardware is the USART universal synchronous/asynchronous...