Book Image

The Insider's Guide to Arm Cortex-M Development

By : Zachary Lasiuk, Pareena Verma, Jason Andrews
Book Image

The Insider's Guide to Arm Cortex-M Development

By: Zachary Lasiuk, Pareena Verma, Jason Andrews

Overview of this book

Cortex-M has been around since 2004, so why a new book now? With new microcontrollers based on the Cortex-M55 and Cortex-M85 being introduced this year, Cortex-M continues to expand. New software concepts, such as standardized software reuse, have emerged alongside new topics including security and machine learning. Development methodologies have also significantly advanced, with more embedded development taking place in the cloud and increased levels of automation. Due to these advances, a single engineer can no longer understand an entire project and requires new skills to be successful. This book provides a unique view of how to navigate and apply the latest concepts in microcontroller development. The book is split into two parts. First, you’ll be guided through how to select the ideal set of hardware, software, and tools for your specific project. Next, you’ll explore how to implement essential topics for modern embedded developers. Throughout the book, there are examples for you to learn by working with real Cortex-M devices with all software available on GitHub. You will gain experience with the small Cortex-M0+, the powerful Cortex-M55, and more Cortex-M processors. By the end of this book, you’ll be able to practically apply modern Cortex-M software development concepts.
Table of Contents (15 chapters)
Part 1: Get Set Up
Part 2: Sharpen Your Skills

Measuring cycle count

Cortex-M processors provide multiple ways to compare the performance of different implementations of an algorithm. One way is to use a cycle counter register. Another way is to use a timer to measure the time of execution and convert the time into clock cycles using the processor frequency. The most recent Cortex-M microcontrollers contain a full performance monitoring unit (PMU), which enables software to get information about the count of various events occurring while the software is executing. One of the measured events can be a cycle counter, but additional events such as cache and memory accesses can also be counted.

This section will cover how to use the most common methods of counting cycles for a specific section of code on Cortex-M microcontrollers. First, we will introduce System Tick Timer or System Time Tick (SysTick) followed by Data Watchpoint and Trace (DWT). Both these programming interfaces can be used to count clock cycles for a benchmark...