Arduino Internals. Dale Wheat. Apress

Transcription

1 Arduino Internals Dale Wheat Apress

2 Contents About the Authors About the Technical Reviewers Acknowledgments Preface xv xvi xvii xviii Chapter 1: Hardware 1 What Is an Arduino? 1 The Arduino Uno 2 Processor 3 Serial Port 5 Power Supply 5 Expansion Connectors 6 Shields 9 The Arduino Mega Previous Hardware 16 Arduino Serial 16 Arduino USB 17 Arduino Extreme 18 Arduino Nuova Generazione (New Generation) 18 Arduino Diecimila 18 Arduino Duemilanove 18 Arduino Mega 19 V

3 Who Makes Arduinos? 19 Officially Licensed Products 19 Everybody Else 20 Build Your Own 21 Arduino Printed Circuit Boards 21 Breadboard Arduinos 22 Summary 23 Chapter 2: Software Hosts and Targets 25 Step by Step 26 Step 1: Write Some Code 26 Step 2: Compile the Code 31 Step 3: Program the Device 33 Step 4: Test and Debug 33 Step 5. Repeat 34 Semiautomatic 34 Blinking in С 34 Going Further 37 Summary 37 Chapter 3: Atmel AVR 39 Origins 39 AVR Device Families 39 When in Doubt: Product Datasheets 40 Device Packaging 40 Through-Hole DIPs 40 Surface-Mount Devices (SMDs) 41 Extra Pins 42

4 Pin Descriptions 43 Power Pins 43 AVRCore 50 Clock Sources 54 Address Spaces 55 Instruction Set 58 Internal Peripherals 65 General Purpose Input/Output (I/O) 65 External Interrupts 66 Timer/Counters 66 USART 67 Two-Wire Serial Interface (TWl), a.k.a. I 2 C 68 Analog Inputs 68 Summary 68 Chapter 4: Supporting Hardware...71 Schematic Diagrams 71 Component Types 72 Reference Designators 72 Component Values 73 Component Value Tolerances 74 Other Component Parameters 74 The Connections 75 Getting Power to the Board 75 The Barrel Connector 76 Input Power Conditioning 76 Voltage Regulator 78 Power Circuit Evolution 79 vii

5 Serial Interface 81 RS-232 Interface 81 The Processor 83 Power Consumption 83 I/O Drive Capability 84 The-RESET Signal 84 The Time Base 84 Decoupling Capacitors 85 Blinky Lights 85 Room for Expansion 85 The Mechanical Form Factor 86 Universal Serial Bus (USB): Signals Plus Power 87 Summary 88 Chapter 5: Arduino Software 89 Open Source Software 90 Multiplatform Support 90 The Arduino Heritage 91 Installing the Software 91 The Process, or "How to Arduino" 91 A Tour of the User Interface 93 The File Menu 94 The Edit Menu and the Edit Context Menu 94 The Sketch Menu 95 The Tools Menu 95 The Help Menu 97 Summary 97 viii

6 Chapter 6: Optimizations 99 How Will You Know It Worked? 99 Shrink Blink 100 How Blink Works 100 Measuring Space-Saving Optimizations 100 Code Analysis 101 Life Without pinmodeo 101 Abbr. & Shrtcts 102 Binary Notation 103 Further Analysis 103 Easy Toggling 104 Further Reduction 105 Wasting Time More Efficiently 105 Using Lower-Level Code 106 Saving Space with Simple Serial Communication 107 What "Hello, world!" Does 107 Writing to Configuration Registers 108 Transmitting Data 109 A String of Characters 111 Printing Numbers 112 Saving SRAM 112 Measuring SRAM Requirements 113 The Bare Minimum 114 Memory Sections 116 Where Variables Live 117 Using the Appropriate Data Type 117 Strings of Characters, Revisited 118 Low Power or High Speed? 120

7 Electronic Measurements 121 The Arduino as Test Equipment 121 As Fast As Possible 124 Slowing It Down 127 Further Power Reductions 128 Summary 130 Chapter 7: Hardware Plus Software 133 Available Peripherals 133 Serial Port(s) 133 General-Purpose Digital Inputs and Outputs 139 Timers and Counters 143 Pulse-Width-Modulation (PWM) Outputs 147 Analog Inputs 152 External Interrupts 156 Interrupt Reference 159 Summary 163 Chapter 8: Example Projects 165 Beyond the Blinking LED: Starting Simply 165 Slow Enough 168 Mostly Optimized Six-Channel Dimmer 170 It's Dim, Alright 173 Other Uses for a Blinking LED 182 Infrared Remote Control 182 TV-B-Gone 183 A Lot of Blinking LEDs 185 A Direct-Drive Example 185 Direct-Drive with LED Drivers 187 Multiplexing Techniques 188

8 A Digital Clock 205 Accuracy 210 User Interface 211 Additional Features 212 Summary 212 Chapter 9: Project Management 213 Documentation 213 Source-Code Comments 214 Whitespace 215 Code What You Mean, Mean What You Code 216 Automated Documentation 217 Writing For Your Audience 217 Hardware Documentation 218 Going Further 220 Teamwork and Collaborative Development 221 Blogs 221 Forums 222 Wikis 222 Revision Control Systems 223 A Note About Revision- or Version-Numbering 223 Project-Hosting Web Sites 224 Licensing Your Work 226 Patents and Trademarks 227 Copyright 228 Open Source 229 The Public Domain 230 Summary 230 xi

9 Chapter 10: Hardware Design 231 Learning About Hardware 231 Things You Must Have 232 Things You Want 233 Infrared Proximity Sensor 234 A Modest Prototype 236 Some Modest Improvements 238 Printed Circuit Boards 241 PCB Layout Techniques 243 A First Attempt 244 A More Compact Version 245 Making the Connection 246 Your Own Custom Arduino 247 Compatibility with Existing Arduinos and Shields 247 Power Supply Options 249 Processor Selection 249 Anything Else? 250 Design Software 251 CadSoft EAGLE 251 EAGLE Tips 252 Summary 253 Chapter 11: Software Design 255 Advanced Topics Within Arduino 255 Writing Arduino Libraries 255 Alternate Cores 262 XI1

10 And Without Arduino 273 The Bare Metal, Revisited 273 Other Development Environments 275 Summary 279 Chapter 12: Networking 281 Point-to-Point Networking 281 Talking Over the Serial Port 281 Arduino to Arduino 283 MIDI: Musical Instrument Digital Interface 296 The Internet 301 Summary 304 Chapter 13: More Example Projects 305 An Autonomous Robot 305 Power Supply 306 Motion Control 306 Electric Motors and Actuators 307 Sensors 312 Light Sensors 312 Touch Sensors 313 Noncontact Sensors 314 Audio Sensors 315 Indicators, Controls, and Other Forms of Communication 315 Control Systems 316 Open-Loop Systems 317 Closed-Loop Systems 317 xin

11 Example Robot Projects 319 A Practice Robot 319 The Next Robot 341 Your Ultimate Robot 357 Summary 358 Index 359 XIV