Chapter 1

Discovering Arduino

IN THIS CHAPTER

Discovering what Arduino is

Learning where Arduino came from

Introducing the basic principles

Arduino is made up of both hardware and software.

The Arduino board is a printed circuit board (PCB) designed to use a microcontroller chip as well as other inputs and outputs. The board has many other electronic components that are needed for the microcontroller to function or to extend its capabilities.

A microcontroller is a small computer contained in a single, integrated circuit or computer chip. Microcontrollers are an excellent way to program and control electronics. Microcontroller boards have a microcontroller chip and other useful connectors and components that allow a user to attach inputs and outputs. Some examples of devices with microcontroller boards are the Wiring board, the Basic Stamp, and PIC development boards.

You write code in the Arduino software to tell the microcontroller what to do. For example, by writing a line of code, you can tell a light-emitting diode (LED) to blink on and off. If you connect a pushbutton and add another line of code, you can tell the LED to turn on only when the button is pressed. Next, you may want to tell the LED to blink only when the pushbutton is held down. In this way, you can quickly build a behavior for a system that would be difficult to achieve without a microcontroller.

Similar to a conventional computer, an Arduino can perform a multitude of functions, but it's not much use on its own. It requires inputs or outputs to make it useful. These inputs and outputs allow a computer - and an Arduino - to sense objects in the world and to affect the world.

Before you move forward, it might help you to understand a bit of the history of Arduino.

Where Did Arduino Come From?

Arduino started its life in Italy, at Interaction Design Institute Ivrea (IDII), a graduate school for interaction design that focuses on how people interact with digital products, systems, and environments and how they in turn influence us.

The term interaction design was coined by Bill Verplank and Bill Moggridge in the mid-1980s. The sketch in Figure 1-1 by Verplank illustrates the basic premise of interaction design: If you do something, you feel a change, and from that you can know something about the world.

Courtesy of Bill Verplank

FIGURE 1-1: The principle of interaction design, illustrated by Bill Verplank.

Although interaction design is a general principle, it more commonly refers specifically to how we interact with conventional computers by using peripherals (such as mice, keyboards, and touchscreens) to navigate a digital environment that is graphically displayed on a screen.

Another avenue, referred to as physical computing, is about extending the range of these computer programs, software, or systems through electronics. By using electronics, computers can sense more about the world and have a physical effect on the world themselves.

Both areas - interaction design and physical computing - require prototypes to fully understand and explore the interactions, which presented a hurdle for non-technical design students.

In 2001, a project called Processing, started by Casey Reas and Benjamin Fry, aimed to get non-programmers into programming by making it quick and easy to produce onscreen visualizations and graphics. The project gave the user a digital sketchbook on which to try ideas and experiment with a small investment of time. This project in turn inspired a similar project for experimenting in the physical world.

In 2003, building on the same principles as Processing, Hernando Barragán started developing a microcontroller board called Wiring. This board was the predecessor to Arduino.

In common with the Processing project, the Wiring project also aimed to involve artists, designers, and other non-technical people. However, Wiring was designed to get people into electronics as well as programming. The Wiring board (shown in Figure 1-2) was less expensive than some other microcontrollers, such as the PIC and the Basic Stamp, but it was still a sizable investment for students.

FIGURE 1-2: An early Wiring board.

In 2005, the Arduino project began in response to the need for affordable and easy-to-use devices for interaction design students to use in their projects. It is said that Massimo Banzi and David Cuartielles named the project after Arduin of Ivrea, an Italian king, but I've heard from reliable sources that it also happens to be the name of the local pub near the university, which may have been of more significance to the project.

The Arduino project drew from many of the experiences of both Wiring and Processing. For example, an obvious influence from Processing is the graphic user interface (GUI) in the Arduino software. This GUI was initially "borrowed" from Processing, and even though it still looks similar, it has since been refined to be more specific to Arduino. I cover the Arduino interface in more depth in Chapter 3.

Arduino also kept the naming convention from Processing, calling its programs sketches. In the same way that Processing gives people a digital sketchbook to create and test programs quickly, Arduino gives people a way to sketch their hardware ideas as well. Throughout this book, I show many sketches that allow your Arduino to perform a huge variety of tasks. By using and editing the example sketches in this book, you can quickly build up your understanding of how they work. You'll be writing your own in no time. Each sketch is followed with a line-by-line explanation of how it works to ensure that no stone is left unturned.

The Arduino board, shown in Figure 1-3, was made to be more robust and forgiving than Wiring and other earlier microcontrollers. It was not uncommon for students, especially those from a design or arts background, to break their microcontroller within minutes of using it, simply by getting the wires the wrong way around. This fragility was a huge problem, not only financially but also for the success of the boards outside technical circles.

Another important difference between Arduino and other microcontroller boards is the cost. Back in 2006, another popular microcontroller, the Basic Stamp, cost nearly four times as much ($119) as an Arduino ($32). Today, an Arduino Uno costs just $27.

In one of my first Arduino workshops, I was told that the price was intended to be affordable for students. The price of a nice meal and a glass of wine at that time was about $42, so if you had a project deadline, you could choose to skip a nice meal that week and make your project instead.

The range of Arduino boards on the market is a lot bigger than it was back in 2006. In Chapter 2, you learn about just a few of the most useful Arduino and Arduino-compatible boards and how they differ to provide you with a variety of solutions for your own projects. Also, in Chapter 12, you learn all about a special type of circuit board called a shield, which can add useful, and in some cases phenomenal, features to your Arduino, turning it into a GPS (Global Positioning System) receiver, a mobile phone, or even a Geiger counter, to name just a few.

FIGURE 1-3: The original Arduino Serial board.

Learning by Doing

People have used technology in many ways to achieve their own goals without needing to delve into the details of electronics. Following are just a few related schools of thought that have allowed people to play with electronics.

Patching

Patching is a technique for experimenting with systems using wires. The earliest popular example of patching is in phone switchboards. For an operator to put you through to another line, he or she had to physically attach a cable.

This technique was also popular for synthesizing music, such as with the Moog synthesizer. When an electronic instrument generates a sound, it's really generating a voltage. Different collections of components in the instrument manipulate that voltage before it is outputted as an audible sound. The Moog synthesizer works by changing the path that that voltage takes, sending it through a number of different components to apply different effects.

Because so many combinations are possible, the musician proceeds largely through trial and error. But the simple interface means that this process is extremely quick and requires little preparation to get going.

Hacking

Hacking is a term that typically refers to the subversive use of technology. More generally, though, it refers to exploring systems and making full use of them or repurposing them to suit your needs.

Hacking in this sense is possible in hardware as well as software. A great example of hardware hacking is a keyboard hack. Say that you want to use a big red button to move through a slideshow. Most software programs contain keyboard shortcuts, and most PDF viewers move to the next page in a slideshow when the user presses the spacebar. If you know this, you ideally want a keyboard with only a spacebar.

Today's keyboards have a small circuit board, a bit smaller than a credit card (see Figure 1-4), containing lots of contacts that are connected when you press different keys. If you can find the correct combination, you can connect two...