Book Image

ARM® Cortex® M4 Cookbook

By : Mark Fisher, Dr. Mark Fisher
Book Image

ARM® Cortex® M4 Cookbook

By: Mark Fisher, Dr. Mark Fisher

Overview of this book

Embedded microcontrollers are at the core of many everyday electronic devices. Electronic automotive systems rely on these devices for engine management, anti-lock brakes, in car entertainment, automatic transmission, active suspension, satellite navigation, etc. The so-called internet of things drives the market for such technology, so much so that embedded cores now represent 90% of all processor’s sold. The ARM Cortex-M4 is one of the most powerful microcontrollers on the market and includes a floating point unit (FPU) which enables it to address applications. The ARM Cortex-M4 Microcontroller Cookbook provides a practical introduction to programming an embedded microcontroller architecture. This book attempts to address this through a series of recipes that develop embedded applications targeting the ARM-Cortex M4 device family. The recipes in this book have all been tested using the Keil MCBSTM32F400 board. This board includes a small graphic LCD touchscreen (320x240 pixels) that can be used to create a variety of 2D gaming applications. These motivate a younger audience and are used throughout the book to illustrate particular hardware peripherals and software concepts. C language is used predominantly throughout but one chapter is devoted to recipes involving assembly language. Programs are mostly written using ARM’s free microcontroller development kit (MDK) but for those looking for open source development environments the book also shows how to configure the ARM-GNU toolchain. Some of the recipes described in the book are the basis for laboratories and assignments undertaken by undergraduates.
Table of Contents (16 chapters)
ARM Cortex M4 Cookbook
About the Author
About the Reviewer

Multithreaded programs using mailboxes

The event flags that we saw in the last recipe can only been used to trigger the execution of tasks. In contrast to this, mailboxes support the exchange of program data between tasks. CMSIS-RTOS provides a mailbox system that buffers messages into mail slots and queues them between the sending and receiving tasks. This recipe, RTOS_Blinky_c8v1, provides an introduction to sending fixed-length messages between tasks using mailboxes.

How to do it…

  1. Clone the RTOS_Blinky_c8v0 folder in the Multithreaded programs using event flags recipe that we described earlier.

  2. Replace taskA( ) with the following function definition:

    void taskA (void const *argument) {
      uint32_t i=0;
      for (;;) {
        mail_t *mail = (mail_t*)osMailAlloc(mail_box,
        mail->counter = i++;
        osMailPut(mail_box, mail);
  3. Replace taskB( ) with the following function definition:

    void taskB (void const *argument...