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

Handling interrupts in assembly language

ARM Cortex interrupt handlers can be programmed completely in C, but programmers coding time-critical applications prefer to use assembler (some programmers claim, rather ambitiously, that their hand-crafted assembler programs run up to 30-times faster than compiler generated code, but I suspect that the actual figure is 2-3 times).

When an interrupt (also known as an exception) occurs, the processor responds by performing the following actions:

  • Pushing Registers R0-R3, R12, link register (LR), program counter (PC), and program status (PSR) onto the stack

  • Reading the address of the exception handler from the interrupt vector table

  • Updating the stack pointer, program status, link register, and program counter

The eight words pushed onto the stack are collectively known as the Stack Frame (illustrated later). These are referred to as caller-saved registers by the (AAPCS), and so the exception executes exactly as a C function. If the processor is in privileged...