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Arduino™ Sketches

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Arduino™ Sketches

James A. Langbridge

Tools and Techniques for Programming Wizardry

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Arduino™ Sketches: Tools and Techniques for Programming Wizardry

Published by

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Copyright © 2015 by John Wiley & Sons, Inc., Indianapolis, Indiana

Published simultaneously in Canada

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To my loving girlfriend, Anne-Laure, who once again put up with entire evenings and weekends spent on my PC. This is the second time I’ve done that to her, but she put up with me anyway and kept on smiling (most of the time). I still don’t know how.

To my wonderful daughter, Eléna: I have to admit, I’m addicted to your laugh and smile, something you did every time I showed you the projects I was working on. Again you found a way of telling me when I needed to stop and spend more time

playing with you (by unplugging and randomly rewiring my breadboard projects), but coming back home at the end of a long and difficult day to see you smiling and

jumping into my arms gave me more energy than you can imagine.

vii

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James A. Langbridge does not like talking about himself in the third person,

but he will try anyway. James was born in Singapore and followed his parents

to several countries before settling down in Nantes, France, where he lives with

his partner and their daughter.

James is an embedded systems consultant and has worked for more than 15

years on industrial, military, mobile telephony, and aviation security systems.

He works primarily on low-level development, creating bootloaders or opti-

mizing routines in assembly, making the most of small processors. When not

on contract, James trains engineers on embedded systems, or he makes new

gizmos, much to the dismay of his partner.

James wrote his fi rst computer program at age 6 and has never stopped tin-

kering since. He began using Apple IIs, ZX80s and ZX81s, and then moved to

BBC Micros and the Amiga before fi nally having no other option but to use PCs.

About the Author

ix

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Scott Fitzgerald is an artist and educator working with technology and its rela-

tionship to people, approaching digital tools from a human-centric perspective.

His work has been featured in numerous books and publications such as The New York Times and IDN Magazine. He has edited several books on Arduino

and communication technologies, is the author of the book that accompanies

the Arduino Starter Kit, and is responsible for documentation of the Arduino

platform at http://arduino.cc. Scott is currently an assistant arts professor and

head of the interactive media program at New York University Abu Dhabi. He

enjoys tormenting his cat and partner with early morning work sessions.

About the Technical Editor

xi

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Credits

Project EditorChristina Haviland

Technical ProofreaderYing Chin

Production EditorRebecca Anderson

Copy EditorSan Dee Phillips

Manager of Content Development and AssemblyMary Beth Wakefi eld

Marketing DirectorDavid Mayhew

Marketing ManagerCarrie Sherrill

Professional Technology and Strategy DirectorBarry Pruett

Business ManagerAmy Knies

Associate PublisherJim Minatel

Project Coordinator, CoverPatrick Redmond

ProofreaderSarah Kaikini, Word One New York

IndexerJohnna VanHoose Dinse

Cover DesignerMichael E. Trent/Wiley

Cover Image© iStock.com/johnbloor

xiii

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Writing a book is a huge project. When I was at school, I used to shudder at the

thought of writing 1,000 words for an essay, and I was alone to do it. This book

is, of course, much longer, and I enjoyed every minute of it, thanks to the team

of professionals who helped me every step of the way. Take a quick look at the

people involved in this project, and you will soon see what I’m talking about.

I can’t thank everyone involved personally; there are just too many people,

but there are a few names that I will never forget. My thanks go out to Christina

Haviland, my project editor. When I knew that I would be working with her

again, I was thrilled. She actually managed to put up with me for the entire

duration and didn’t even shout at me when I was late, despite the fact that some

of the chapters were very, very late. I was also thrilled to know that I’d be work-

ing with San Dee Phillips, my copy editor. The job they did transforming raw

data coming out of my brain into something readable is outstanding. Then there

is Scott Fitzgerald, my technical editor, who made sure that I didn’t make any

mistakes. Believe me, nothing slipped by, and despite all the grumbling I did

when I received the corrections, thank you! This wouldn’t have been possible

without you.

I would also like to thank Atmel for their time and effort, for the engineers

I was in contact with to get more information, and to Tom Vu who kept on

encouraging me along the way and sending me new evaluation boards to play

with. My thanks also go out to Silicon Labs for its excellent UV sensor that is

presented in this book and for the time it spent helping me. Thanks to Materiel

.net who managed to get me a new computer, camera, and components in record

time when mine broke, allowing me to get the job done. Your coffee mug is still

on my desk!

Acknowledgments

xiv Acknowledgments

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Of course, this book would not have been possible without the amazing

people at Arduino. I don’t know if they know just how much they have changed

the world of makers. Your boards have brought back the joy I had in creating

gizmos and contraptions.

This has been a huge adventure, and I’ve met a lot of amazing people along

the way. Thank you to every one of you—for your time, your suggestions, and

your encouraging messages.

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Introduction xxix

Part I Introduction to Arduino 1

Chapter 1 Introduction to Arduino 3

Chapter 2 Programming for the Arduino 25

Chapter 3 Electronics Basics 45

Part 2 Standard Libraries 63

Chapter 4 The Arduino Language 65

Chapter 5 Serial Communication 81

Chapter 6 EEPROM 101

Chapter 7 SPI 117

Chapter 8 Wire 133

Chapter 9 Ethernet 149

Chapter 10 WiFi 169

Chapter 11 LiquidCrystal 191

Chapter 12 SD 207

Chapter 13 TFT 225

Chapter 14 Servo 241

Chapter 15 Stepper 253

Chapter 16 Firmata 261

Contents at Glance

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xvi Contents at Glance

Chapter 17 GSM 271

Part III Device Specifi c Libraries 289

Chapter 18 Audio 291

Chapter 19 Scheduler 305

Chapter 20 USBHost 321

Chapter 21 Esplora 335

Chapter 22 Robot 345

Chapter 23 Bridge 361

Part IV User Libraries and Shields 375

Chapter 24 Importing Third-Party Libraries 377

Chapter 25 Creating Your Own Shield 391

Chapter 26 Creating Your Own Library 405

Index 429

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Contents

Introduction xxix

Part I Introduction to Arduino 1

Chapter 1 Introduction to Arduino 3

Atmel AVR 5The Arduino Project 7The ATmega Series 8

The ATmega Series 8

The ATtiny Series 8

Other Series 9

The Different Arduinos 9Arduino Uno 10

Arduino Leonardo 10

Arduino Ethernet 11

Arduino Mega 2560 11

Arduino Mini 13

Arduino Micro 13

Arduino Due 13

LilyPad Arduino 14

Arduino Pro 16

Arduino Robot 16

Arduino Esplora 18

Arduino Yún 18

Arduino Tre 19

Arduino Zero 19

Your Own Arduino? 20

Shields 20What Is a Shield? 20

The Different Shields 21

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Arduino Motor Shield 21

Arduino Wireless SD Shield 21

Arduino Ethernet Shield 21

Arduino WiFi Shield 22

Arduino GSM Shield 22

Your Own Shield 22

What Can You Do with an Arduino? 22What You Will Need for This Book 23Summary 24

Chapter 2 Programming for the Arduino 25

Installing Your Environment 26Downloading the Software 27

Running the Software 28

Using Your Own IDE 29

Your First Program 29Understanding Your First Sketch 33Programming Basics 36

Variables and Data Types 36

Control Structures 38

if Statement 38

switch Case 39

while Loop 40

for Loop 41

Functions 42

Libraries 42

Summary 42

Chapter 3 Electronics Basics 45

Electronics 101 46Voltage, Amperage, and Resistance 46

Voltage 47

Amperage 48

Resistance 48

Ohm’s Law 49

The Basic Components 49Resistors 50

Different Resistor Values 50

Identifying Resistor Values 50

Using Resistors 52

Capacitors 53

Using Capacitors 54

Diodes 54

Different Types of Diodes 54

Using Diodes 55

Light-Emitting Diodes 55

Using LEDs 55

Transistors 56

Contents xix

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Using Transistors 56

Breadboards 56Inputs and Outputs 57Connecting a Light-Emitting Diode 58

Calculation 58

Software 59

Hardware 60

What Now? 61

Summary 61

Part II Standard Libraries 63

Chapter 4 The Arduino Language 65

I/O Functions 65Digital I/O 65

pinMode() 66

digitalRead() 66

digitalWrite() 67

Analog I/O 67

analogRead() 68

analogWrite() 68

Generating Audio Tones 69

tone() 69

noTone() 69

Reading Pulses 69

pulseIn() 70

Time Functions 70delay() 70

delayMicroseconds() 71

millis() 71

micros() 71

Mathematical Functions 72min() 72

max() 72

constrain() 73

abs() 73

map() 73

pow() 74

sqrt() 74

random() 74

Trigonometry 75sin() 76

cos() 76

tan() 76

Constants 76

Interrupts 76

xx Contents

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attachInterrupt() 77

detachInterrupt() 78

noInterrupts() 78

interrupts() 78

Summary 79

Chapter 5 Serial Communication 81

Introducing Serial Communication 82UART Communications 84

Baud Rate 84

Data Bits 85

Parity 85

Stop Bits 86

Debugging and Output 86Starting a Serial Connection 87Writing Data 88

Sending Text 88

Sending Data 90

Reading Data 91Starting Communications 91

Is Data Waiting? 91

Reading a Byte 92

Reading Multiple Bytes 92

Taking a Peek 93

Parsing Data 93

Cleaning Up 94

Example Program 95SoftwareSerial 98Summary 99

Chapter 6 EEPROM 101

Introducing EEPROM 101The Different Memories on Arduino 103The EEPROM Library 104

Reading and Writing Bytes 104

Reading and Writing Bits 105

Reading and Writing Strings 107

Reading and Writing Other Values 108

Example Program 110

Preparing EEPROM Storage 113Adding Nonvolatile Memory 114Summary 115

Chapter 7 SPI 117

Introducting SPI 118SPI Bus 118

Comparison to RS-232 119

Confi guration 119

Communications 120

Contents xxi

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Arduino SPI 120SPI Library 121SPI on the Arduino Due 123Example Program 125

Hardware 126

Sketch 128

Exercises 131

Summary 132

Chapter 8 Wire 133

Introducing Wire 134Connecting I2C 135I2C Protocol 135

Address 136

Communication 137

Communicating 138Master Communications 139

Sending Information 139

Requesting Information 140

Slave Communications 141

Receiving Information 141

Sending Information 142

Example Program 142

Exercises 146

Traps and Pitfalls 147Voltage Difference 147

Bus Speed 147

Shields with I2C 148

Summary 148

Chapter 9 Ethernet 149

Introduction 149Ethernet 150

Ethernet Cables 151

Switches and Hubs 151

PoE 152

TCP/IP 152MAC Address 153

IP Address 153

DNS 153

Port 153

Ethernet on Arduino 154Importing the Ethernet Library 154

Starting Ethernet 155

Arduino as a Client 157Sending and Receiving Data 158

Connecting to a Web Server 159

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Example Program 161

Arduino as a Server 163

Serving Web Pages 164

Example Program 165

Sketch 165

Summary 167

Chapter 10 WiFi 169

Introduction 170The WiFi Protocol 171

Topology 171

Network Parameters 172

Channels 172

Encryption 172

SSID 173

RSSI 173

Arduino WiFi 173Importing the Library 174

Initialization 174

Status 175

Scanning Networks 176

Connecting and Confi guring 177

Wireless Client 178

Wireless Server 179

Example Application 179Hardware 181

Sketch 182

Exercises 189

Summary 190

Chapter 11 LiquidCrystal 191

Introduction 192LiquidCrystal Library 194

Writing Text 195

Cursor Commands 196

Text Orientation 197

Scrolling 197

Custom Text 198

Example Program 199Hardware 200

Software 201

Exercises 205

Summary 205

Chapter 12 SD 207

Introduction 208SD Cards 211

Capacity 212

Speed 213

Contents xxiii

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Using SD Cards with Arduino 213Accepted SD Cards 214

Limitations 214

The SD Library 215Importing the Library 215

Connecting a Card 215

Opening and Closing Files 216

Reading and Writing Files 217

Reading Files 217

Writing Files 218

Folder Operations 218

Card Operations 219

Advanced Usage 220

Example Program and Sketch 220Summary 224

Chapter 13 TFT 225

Introduction 226Technologies 227TFT Library 228

Initialization 228

Screen Preparation 229

Text Operations 230

Basic Graphics 231

Coloring 232

Graphic Images 232

Example Application 233Hardware 234

Sketch 234

Exercises 239

Summary 239

Chapter 14 Servo 241

Introduction to Servo Motors 242Controlling Servo Motors 243

Connecting a Servo Motor 243

Moving Servo Motors 244

Disconnecting 245

Precision and Safety 246

Example Application 246Schematic 248

Sketch 249

Exercises 250

Summary 251

Chapter 15 Stepper 253

Introducing Motors 254Controlling a Stepper Motor 254

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Hardware 255

Unipolar Versus Bipolar Stepper Motors 255

The Stepper Library 256Example Project 257

Hardware 257

Sketch 258

Summary 260

Chapter 16 Firmata 261

Introducing Firmata 262Firmata Library 262

Sending Messages 263

Receiving Messages 263

Callbacks 264

SysEx 266

Example Program 268Summary 269

Chapter 17 GSM 271

Introducing GSM 272Mobile Data Network 272

GSM 273

GPRS 274

EDGE 274

3 G 274

4 G and the Future 275

Modems 275

Arduino and GSM 276Arduino GSM Library 276

GSM Class 278

SMS Class 279

VoiceCall Class 281

GPRS 282

Modem 284

Example Application 285Summary 288

Part III Device-Specifi c Libraries 289

Chapter 18 Audio 291

Introducing Audio 292Digital Sound Files 292Music on the Arduino 294Arduino Due 294

Digital to Analog Converters 295

Digital Audio to Analog 295

Creating Digital Audio 296

Storing Digital Audio 296

Playing Digital Audio 296

Contents xxv

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Example Program 298Hardware 298

Sketch 300

Exercise 303

Summary 304

Chapter 19 Scheduler 305

Introducing Scheduling 306Arduino Multitasking 307Scheduler 308

Cooperative Multitasking 309

Noncooperative Functions 311

Example Program 313Hardware 314

Sketch 316

Exercises 319

Summary 319

Chapter 20 USBHost 321

Introducing USBHost 322USB Protocol 323USB Devices 324

Keyboards 324

Mice 325

Hubs 325

Arduino Due 325USBHost Library 327

Keyboards 327

Mice 329

Example Program 330Hardware 331

Source Code 332

Summary 334

Chapter 21 Esplora 335

Introducing Esplora 336The Arduino Esplora Library 337

RGB LED 337

Sensors 338

Buttons 339

Buzzer 340

TinkerKit 341

LCD Module 342

Example Program and Exercises 342Summary 344

Chapter 22 Robot 345

Introducing Robot Library 346Arduino Robot 348

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Robot Library 349Control Board 350

Robotic Controls 350

Sensor Reading 351

Personalizing Your Robot 353

LCD Screen 354

Music 356

Motor Board 357

Example Program and Exercises 358Summary 360

Chapter 23 Bridge 361

Introducing Bridge Library 362Bridge 363

Process 364

FileIO 366

YunServer 367

YunClient 368

Example Application 369Hardware 369

Sketch 370

Exercises 373

Summary 373

Part IV User Libraries and Shields 375

Chapter 24 Importing Third-Party Libraries 377

Libraries 378Finding Libraries 378

Importing a Library 379

Using an External Library 381

Example Application 384Exercises 389Summary 389

Chapter 25 Creating Your Own Shield 391

Creating a Shield 391The Idea 392

The Required Hardware 392

The Required Software 393

Your First Shield 394Step 1: The Breadboard 395

Step 2: The Schematic 398

Step 3: The PCB 402

Summary 404

Contents xxvii

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Chapter 26 Creating Your Own Library 405

Libraries 405Library Basics 406

Simple Libraries 406

Advanced Libraries 410

Adding Comments 413

Adding Examples 415

Read Me 415

Coding Style 416

Use CamelCase 416

Use English Words 416

Don’t Use External Libraries 417

Use Standard Names 417

Distributing Your Library 417

Closed Source Libraries 417

Example Library 418The Library 418

Examples 424

README 427

Finishing Touches 428

Summary 428

Index 429