This book explores how to use Assembly Language within your Arduino sketches, directly from the Arduino IDE, without any external tools. By learning to write low-level code, you’ll gain the ability to reduce sketch size, increase execution speed, and achieve precise timing control, especially useful for tasks like bit-banging communication protocols.

It’s designed to be both educational and practical, helping developers and makers to reduce the size of their sketches, increase the speed of execution, and to get a much better understanding of how the Arduino hardware works. With a focus on clarity and hands-on examples, it’s ideal for developers and makers who want to push their Arduino projects further and gain deeper insight into microcontroller programming.

What You'll Learn

• How to code in Assembly for speed, code size and exact timings.

• How to write libraries for use with Assembly (and C++ for some of the libraries).

• How to interact with all the hardware features of the ATmega328P, from Assembly Language.

• What to avoid and other pitfalls.

Who Is This Book For

Everyone with an interest in the Arduino boards based on the ATmega328P. All levels but a passing understanding of some programming languages would be helpful.

Table of Contents

1 Introduction

2 Background

3 Digital Input and Output

4 Serial Output and Input

5 Parameter Passing

6 Returning Values

7 Arithmetic

8 The SimulAVR Simulator

9 Logic

10 Libraries

11 Timer Functions

12 Conditional Branching

13 Sleeping

14 The Watchdog Timer

15 Pin Synchronization

16 Analog Input and Output

17 AVR Libgcc Functions

18 Generating Assembly Listings

19 Capacitance Sensor

20 Using the EEPROM

21 Odds and Sods

22 Analog Comparator

23 Liquid Crystal Library

24 SPI: Serial Peripheral Interface

25 12C: Two-Wire Interface

26 LM75A Examples

A Atmega328P SFRs: Special Function Registers

B Assembler Differences

C More Switch Debouncing

About the Author

Norman Dunbar is a retired Oracle database administrator. Norman has had a long-running relationship with electronics since childhood and computers since the late 1970s, and the Arduino was a perfect marriage of the two interests.

With a love of learning new things, examining and explaining the Arduino Language and the hardware became a bit of a hobby, and as his piles of notes expanded, Apress decided to publish his work as Arduino Software Internals back in April 2020 with a second edition in 2024.

Once more his notes became a book and Arduino Interrupts was published by Apress/Springer in December 2023. Because he never remembers exactly how much work, and how hard it is to write a technical book, Norman has now completed writing the third book in the Arduino Trilogy, and you are reading it now! Norman’s motto continues to be don’t think, find out.