The BeagleBone is amazing! Given the proliferation of smartphones, the idea of holding in one hand a computer that is capable of performing two billion instructions per second is easy to take for granted—but the fact that you can modify the hardware and software of such a small yet powerful device and adapt it to suit your own needs and create your own inventions is nothing short of amazing. Even better, you can purchase it for as little as $45–$55.

The BeagleBone board on its own is too complex a device to be used by a general audience; it is the ability of the BeagleBone to run embedded Linux that makes the resulting platform accessible, adaptable, and powerful. Together, Linux and embedded systems enable ease of development for devices that can meet future challenges in smart buildings, the Internet of Things (IoT), robotics, smart energy, smart cities, human-computer interaction (HCI), cyber-physical systems, 3D printing, advanced vehicular systems, and many, many more applications.

The integration of high-level Linux software and low-level electronics represents a paradigm shift in embedded systems development. It is revolutionary that you can build a low-level electronics circuit and then install a Linux web server, using only a few short commands, so that the circuit can be controlled over the Internet. You can easily use the BeagleBone as a general-purpose Linux computer, but it is vastly more challenging and interesting to get underneath the hood and fully interface it to electronic circuits of your own design—and that is where this book comes in!

This book should have widespread appeal for inventors, makers, students, entrepreneurs, hackers, artists, dreamers—in short, anybody who wants to bring the power of embedded Linux to their products, inventions, creations, or projects and truly understand the BeagleBone in detail. This is not a recipe book—with few exceptions, everything demonstrated here is explained at a level that will enable you to design, build, and debug your own extensions of the concepts presented here. Nor is there any grand design project at the end of this book for which you must purchase a prescribed set of components and peripherals in order to achieve a very specific outcome. Rather, this book is about providing you with enough background knowledge and “under-the-hood” technical details to enable and motivate your own explorations.

I strongly believe in learning by doing, so I present low-cost, widely available hardware examples in order that you can follow along. Using these hands-on examples, I describe what each step means in detail, so that when you substitute your own hardware components, modules, and peripherals you will be able to adapt the content in this book to suit your needs. As for that grand project or invention—that is left up to you and your imagination!

When writing this book I had the following aims and objectives:

• To explain embedded Linux and its interaction with electronic circuits—taking you through the topics from mystery to mastery!
• To provide in-depth information and instruction on the Linux, electronics, and programming skills that are required to master a pretty wide and comprehensive variety of topics in this domain.
• To create a collection of practical “Hello World” hardware and software examples on each and every topic in the book, from low-level interfacing, general-purpose input/outputs (GPIOs), analog-to-digital converters (ADCs), buses, and UARTs, to high-level libraries such as OpenCV, Qt, and complex and powerful topics, such as real-time interfacing with the PRU-ICSS.
• To ensure that each circuit and segment of code is specifically designed to work on the BeagleBone. Every single circuit and code example in this book was built and tested on the BeagleBone.
• To use the “Hello World” examples to build a library of code that you can use and adapt for your own BeagleBone projects.
• To make all of the code available on GitHub in an easy-to-use form.
• To support this book with strong digital content, such as the videos on the DerekMolloyDCU YouTube channel, and a custom website www.exploringbeaglebone.com, which has been developed specifically to support this book.
• To ensure that by the end of this book you have everything you need to imagine, create, and build advanced BeagleBone projects.

Why the BeagleBone Black?

The BeagleBone Black is a powerful single-board computer (SBC), and while there are other SBCs available on the market such as the Raspberry PI and the Intel Galileo, the BeagleBone has one key differentiator—it was built to be interfaced to! For example, the BeagleBone's microprocessor even contains two additional on-chip microcontrollers that can be used for real-time interfacing—an area in which other Linux SBCs have significant difficulty.

Unlike most other SBCs, the BeagleBone is fully open source hardware. The BeagleBoard.org Foundation provides source schematics, hardware layout, a full bill of materials, and technical reference manuals, enabling you to modify the design of the BeagleBone platform and integrate it into your own product. In fact, you can even fork the hardware design on Upverter (www.upverter.com) under a Creative Commons Attribution-ShareAlike license (see tiny.cc/ebb002 for the full schematics). This is a very useful feature should you decide to take your newest invention to market!

How This Book Is Structured

There is no doubt that some of the topics in this book are quite complex—the BeagleBone is a complex device! However, everything that you need to master the device is present in the book within three major parts:

• Part I: BeagleBone Basics
• Part II: Interfacing, Controlling, and Communicating
• Part III: Advanced BeagleBone Systems

In the first part in the book, I introduce the hardware and software of the BeagleBone platform in Chapters 1 and 2, and subsequently provide three primer chapters:

• Chapter 3: Exploring Embedded Linux Systems
• Chapter 4: Interfacing Electronics
• Chapter 5: Practical BeagleBone Programming

If you are a Linux expert, electronics wizard, and/or software guru, then feel free to skip the primer chapters; however, for everyone else I have put in place a concise but detailed set of materials to ensure that you gain all the knowledge required to effectively and safely interface to the BeagleBone.

In the second part of the book, Chapters 6 to 9, I provide detailed information on interfacing to the BeagleBone GPIOs, analog inputs, buses (I²C, SPI), UART devices, and USB peripherals. You'll learn how you can configure a cross-compilation environment so that you can build large-scale software applications for the BeagleBone. This part also describes how you can combine hardware and software in order to provide the BeagleBone with the ability to interact effectively with its physical environment.

The final part of the book, Chapters 10 to 13, describe how the BeagleBone can be used for advanced applications such as Internet of Things (IoT); rich user interfaces; images, video, and audio; and real-time interfacing. Along the way you will meet many technologies, including TCP/IP, ThingSpeak, Xively, PoE, Wi-Fi, Bluetooth, cron, Apache, PHP, e-mail, IFTTT, VNC, GTK+, Qt, XML, multi-threading, client/server programming, V4L2, video streaming, OpenCV, Boost, USB audio, Bluetooth A2DP, text-to-speech, and the PRU-ICSS.

Conventions Used in This Book

This book is filled with source code examples and snippets that you can use to build your own applications. Code and commands are shown as follows:

This is what source code looks like.

When presenting work performed in a Linux terminal it is often necessary to display both input and output in a single example. A bold type is used to distinguish the user input from the output—for example:

molloyd@beaglebone:~$ ping www.exploringbeaglebone.com
PING lb1.reg365.net (195.7.226.20) 56(84) bytes of data.
64 bytes from lb1.reg365.net (195.7.226.20): icmp_req=1 ttl=55 time=25.6 ms
64 bytes from lb1.reg365.net (195.7.226.20): icmp_req=2 ttl=55 time=25.6 ms
...

The $ prompt indicates that a regular Linux user is executing a command, and a # prompt indicates that a Linux superuser is executing a command. The ellipsis symbol “...” is used whenever code or output not vital to understanding a topic has been cut. Editing the output like this enables you to focus on only the most useful information. You are encouraged to repeat the steps in this book yourself, whereupon you will see the full output. In addition, the full source code for all examples is provided along with the book.

There are some additional styles in the text. For example:

• New terms and important words appear in italics when introduced.
• Keyboard strokes appear like this: Ctrl+C.
• All URLs in the book refer to HTTP addresses and appear like this: www.exploringbeaglebone.com.
• A URL shortening service is used to create aliases for long URLs that are presented in the book. These aliases have the form tiny.cc/ebb102 (e.g., link two in Chapter 1). Should the link address change after this book is published, the alias will be updated.

There are several features used in this book to identify when content is of particular importance or when additional information is available:

What You'll Need

Ideally you should have a BeagleBone Black before you begin reading this book so that you can follow along with the numerous examples in the text. Presently the board is manufactured by both CircuitCo and Embest—the boards from either manufacturer are compatible with the designs and operations in this book. You can purchase one of the boards in the U.S. from online stores such as Adafruit Industries, Digi-Key, Mouser, SparkFun, and Jameco Electronics. They are available internationally from stores such as Farnell, Radionics, Watterott, and Tigal.

A full list of recommended and optional accessories for the BeagleBone is provided in Chapter 1—if you do not yet have a BeagleBone, it would be worth reading that chapter before placing an order. In addition, each chapter contains a list of the electronics components and modules required if you wish to follow along with the text. The book website provides details about where these components can be acquired.

Errata

We have worked really hard to ensure that this book is error free; however, it is always possible that some were overlooked. A full list of errata is available on each chapter's web page at the companion website. If you find any errors in the text or in the source code examples, I would be grateful if you could please use the companion website to send them to me so that I can update the web page errata list and the source code examples in the code repository.

Digital Content and Source Code

The primary companion site for this book is www.exploringbeaglebone.com. It is maintained by the book's author and contains videos, source code examples, and links to further reading. Each chapter has its own individual web page. In the unlikely event that the website is unavailable, you can find the code at www.wiley.com/go/exploringbeaglebone.

I have provided all of the source code through GitHub, which allows you to download the code to your BeagleBone with one command. You can also easily view the code online at tiny.cc/ebb001. Downloading the source code to your BeagleBone is as straightforward as typing the following at the Linux shell prompt:

$ git clone https://github.com/derekmolloy/exploringBB.git

If you have never used Git before, don't worry—it is explained in detail in Chapter 3. Now, on with the adventures!