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Technology in AcTion
™
Beginning
Arduino
Programming
Writing Code for the Most Popular
Microcontroller Board in the World
Brian Evans
For your convenience Apress has placed some of the front
matter material after the index. Please use the Bookmarks
and Contents at a Glance links to access them.
Contents at a Glance
About the Author ......................................................................................................
About the Technical Reviewer .................................................................................
Acknowledgments ..................................................................................................
Introduction ...........................................................................................................
■
Chapter 1: Getting Started .......................................................................................
1
■
Chapter 2: Sketching in Code ................................................................................
17
■
Chapter 3: Working with Variables........................................................................
33
■
Chapter 4: Making Decisions.................................................................................
47
■
Chapter 5: Digital Ins and Outs..............................................................................
61
■
Chapter 6: Analog In, Analog Out...........................................................................
79
■
Chapter 7: Advanced Functions.............................................................................
95
■
Chapter 8: Arrays and Memory ...........................................................................
121
■
Chapter 9: Hardware Libraries ............................................................................
143
■
Chapter 10: Serial and I2C...................................................................................
175
■
Chapter 11: Continuing On...................................................................................
201
■
Chapter 12: Beginning Electronics ......................................................................
221
■
Appendix: Resources ...........................................................................................
239
Index .......................................................................................................................
iv
Introduction
This book will help you to develop working source code for the Arduino microcontroller. In these pages,
we will primarily concern ourselves with the software aspect of physical computing—designing code to
work with physical objects that exhibit behavior or interactivity through software. Starting with the basic
context of the Arduino platform to getting up and running with our first code, we will discuss the
structure and syntax of Arduino’s C-based programming language, looking at variables, control
structures, arrays, and memory. This book will then go into many of the functions unique to Arduino
development for controlling digital and analog input and output, timing, randomness, writing functions,
and using many of the Arduino libraries for working with different kinds of hardware and
communication protocols.
Arduino, like Processing before it, adopted the idea of a code sketchbook. We will carry on this
metaphor as we talk about the process of sketching in code as an intuitive method for quickly testing out
new ideas in code. Most of this book is written around this idea of developing programming skills
through sketching. We will also provide some suggestions for new projects and hardware, new languages
to try out, and ways to contribute back to the community. This book intentionally does not dwell too
long on electronics theory, circuit design, hacking, or other specifically hardware-based practices,
although we’ll revisit the hardware side of things in our last chapter to provide a small foundation for
physical computing.
This book in many ways picks up where the
Arduino Programming Notebook
left off, with even more
in-depth discussions about the Arduino environment; simple, no-frills code samples; and clear, easy-to-
read schematics and illustrations.
The
Notebook
, a little PDF booklet, was my first experience writing
about the Arduino and was never meant to be more than a brief guide for my students when I first
introduced a class of 15 college art and design majors to the Arduino in 2007. Best laid plans and all, this
little booklet has now been translated into Spanish, Russian, and Dutch (that I know of), is hosted in so
many different places that it is impossible to keep track of, and it’s been used in workshops and classes
around the world. I haven't updated the
Notebook
over the last few years, and in all honesty I am not
entirely sure what to do with it now, so hopefully this new book will fill a void and find a similar,
widespread adoption that the little booklet has enjoyed all these years.
Who This Book is For
This book is written for the primary audience of the Arduino platform: artists, designers, students,
tinkerers, and the makers of things. While you might have some programming experience that you want
to bring to the Arduino platform, we will assume no prior knowledge of writing code. With that said, a
healthy familiarity of the computer is helpful, as is the willingness and inquisitive curiosity to look
beyond this book for certain answers.
The majority of Arduino users just want to get things done and often don’t care about the little
details—they just want their projects to work. I understand this, as I am one of those people. I first
discovered programmable microcontrollers when I was an art student, and at the time, art school was
not generally the most conducive environment for learning how to write code and wire up motors—at
xviii
■
INTRODUCTION
least it wasn’t before the Arduino came along. Likewise, I was never one for a love of mathematics, which
thankfully is not a prerequisite to deeply enjoy the process of writing code.
Reading This Book
Our process in each chapter will be to focus on some fundamental projects that build on the primary
concepts presented in that chapter. For each project, we will begin with a project description and
discuss the specific hardware needed for that project. We will also provide diagrams and illustrations for
making these simple circuits and interfacing them to the Arduino board. As you read through each
project, you should take notes and write in the margins—we won’t be offended. Experiment, try new
things, and see what happens.
The projects demonstrated in this book are meant to be prototypes, or fundamental proof-of-
concept designs for a new device. We will adhere to a degree of minimalism, keeping to simple and
easily obtainable hardware that supports the development of sophisticated written code. Once you have
built the prototype, it can be incorporated into a final project later. We won’t actually be doing that here
so that we can focus on actually writing and developing code. Our examples will borrow and build on
each other throughout the book, revisiting past examples when we need to as our understanding of
writing code develops.
The intent with our code samples is to write compartmentalized or modular code wherever possible
to allow for easy adaptability and future development. We will spend a lot of time developing our coding
skills so that when it comes time to develop a new project independently, you will know where to begin.
The sketches are meant to be fluid—you are encouraged to hack them—changing values, timing, pin
assignments, ranges, and so on—until it no longer works. Then try to fix it. We will stick to a particular
style of writing code in our samples, although we urge you to develop your own writing style that reflects
the way you think and the way you want to see your code.
Wiring up the circuits for our projects is as simple and straightforward as possible, with little to no
understanding of electronics necessary. As a way to reconnect our discussions of programming to the
physical electronics used throughout the book, Chapter 12 will provide a brief review of some basic
electronics, including how circuits work, reading schematics, and an introduction to soldering. If you
find that you are struggling with hooking up the projects in the earlier chapters, you might want to jump
to Chapter 12 for a refresher. Otherwise, this chapter will serve as a good summary that could help
answer some questions you might not even know you had. While this might at first seem a little
backwards, it has worked pretty well in my classes over the last few years.
Arduino 1.0
At the time of this writing, the Arduino developers are hard at work on a more stable, more efficient, and
generally improved version of the Arduino software called Arduino 1.0. The final release version of
Arduino 1.0 should be available right about the same time that this book is published. This is important
because in the process of making things better, some things had to be broken. This means that some
older code written under the alpha release of the Arduino software will no longer work on Arduino 1.0.
Conversely, the code in this book and images of the Arduino development environment have all
been prepared using a beta release of Arduino 1.0 (
so images of the Arduino software may appear different from the final version, some of the code in this
book may not work on older versions of the software, and still other features of 1.0 were not yet fully
implemented—so I couldn’t write about them. There may also be other growing pains with this upgrade
that we are not fully aware of at this time, so if an unusual problem crops up, then you might want to
blame 1.0 and start there to figure out what’s wrong.
xix
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