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
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Using timers to trigger conversions


As sampling frequency plays such a critical role in determining the quality of the digital representation of the analog signal input, and to avoid aliasing artifacts, it is preferable to use a timer to trigger the conversion rather than to enable continuous conversions as we did in the previous recipe. This recipe, adcTimerISR_c5v0, illustrates this technique. The aim of this recipe is to configure TIM2 _CH2 in output compare mode so that it toggles every 100 ms and then use this timing signal to trigger the ADC.

How to do it…

  1. First create a new project called adcTimerISR.uvprojx and use the RTE manager to configure it as we did for the folder adcISR_c5v0 for the Setting up the ADC recipe.

  2. Copy timer.c and Custom_ADC.c from the previous recipes and add these to the project. Copy adcISR.c and rename it adcTimerISR.c. Add this to the project.

  3. Add #include timer.h to adcTimerISR.c and call TIM2_Initialize() in main(). Check whether the project successfully builds...