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

Configuring the audio codec


The STM32F400 evaluation board schematic (http://www.keil.com) shows that a Cirrus Logic CS42L52 codec IC (http://www.cirrus.com) is used, and the I2S bus signals are driven by GPIO port I bits 0, 1, and 3. SDIN and SDOUT are wired together, so the I2S interface must be operated half-duplex. In addition to managing the I2S interface, the microcontroller must also source a Master Clock (MCLK), which clocks the codec's delta-sigma modulators (Note that we described a function to achieve this in Chapter 6, Multimedia Support). A block diagram that summarizes the I2S interface connection is shown, as follows:

The codec also uses MCLK to power an inverter, which supplies a higher DC voltage to support analog parts of the codec. The codec data sheet explains that MCLK should be instantiated and the codec's registers must be configured while the device is powered down and the power up/down sequence outlined in the data sheet must be carefully followed to ensure the codec...