The Arduino core team [from left]—David Cuartielles, Gianluca Martino, Tom Igoe, David Mellis, and Massimo Banzi—get together at Maker Faire in New York City.

Photo: Randi Silberman Klett

The Arduino core team [from left]—David Cuartielles, Gianluca Martino, Tom Igoe, David Mellis, and Massimo Banzi—get together at Maker Faire in New York City.

The picturesque town of Ivrea, which straddles the blue-green Dora Baltea River in northern Italy, is famous for its underdog kings. In 1002, King Arduin became the ruler of the country, only to be dethroned by King Henry II, of Germany, two years later. Today, the Bar di Re Arduino, a pub on a cobblestoned street in town, honors his memory, and that’s where an unlikely new king was born.

The bar is the watering hole of Massimo Banzi, the Italian cofounder of the electronics project that he named Arduino in honor of the place. Arduino is a low-cost microcontroller board that lets even a novice do really amazing things. You can connect an Arduino to all kinds of sensors, lights, motors, and other devices and use easy-to-learn software to program how your creation will behave. You can build an interactive display or a mobile robot and then share your design with the world by posting it on the Net.

Released in 2005 as a modest tool for Banzi’s students at the Interaction Design Institute Ivrea (IDII), Arduino has spawned an international do-it-yourself revolution in electronics. You can buy an Arduino board for just about US \$30 or build your own from scratch: All hardware schematics and source code are available for free under public licenses. As a result, Arduino has become the most influential open-source hardware movement of its time.

The little board is now the go-to gear for artists, hobbyists, students, and anyone with a gadgetry dream. More than 250 000 Arduino boards have been sold around the world—and that doesn’t include the reams of clones. "It made it possible for people do things they wouldn’t have done otherwise," says David A. Mellis, who was a student at IDII before pursuing graduate work at the MIT Media Lab and is the lead software developer of Arduino.

There are Arduino-based breathalyzers, LED cubes, home-automation systems, Twitter displays, and even DNA analysis kits. There are Arduino parties and Arduino clubs. Google has recently released an Arduino-based development kit for its Android smartphone. As Dale Dougherty, the editor and publisher of Make magazine, the bible of DIY builders, puts it, Arduino has become "the brains of maker projects."

But Arduino isn’t just an open-source project that aims to make technology more accessible. It’s also a start-up company run by Banzi and a group of friends, and it’s facing a challenge that even their magic board can’t solve: how to survive success and grow. "We need to make the next jump," Banzi tells me, "and become an established company."

Arduino rose out of another formidable challenge: how to teach students to create electronics, fast. It was 2002, and Banzi, a bearded and avuncular software architect, had been brought on by IDII as an associate professor to promote new ways of doing interactive design—a nascent field sometimes known as physical computing. But with a shrinking budget and limited class time, his options for tools were few.

Like many of his colleagues, Banzi relied on the BASIC Stamp, a microcontroller created by California company Parallax that engineers had been using for about a decade. Coded with the BASIC programming language, the Stamp was like a tidy little circuit board, packing the essentials of a power supply, a microcontroller, memory, and input/output ports for attaching hardware. But the BASIC Stamp had two problems, Banzi discovered: It didn’t have enough computing power for some of the projects his students had in mind, and it was also a bit too expensive—a board plus basic parts could cost about US \$100. He also needed something that could run on Macintosh computers, which were ubiquitous among the IDII designers. What if they could make a board that suited their needs themselves?

Banzi had a colleague from MIT who had developed a designer-friendly programming language called Processing. Processing was rapidly gaining popularity because it allowed even inexperienced programmers to create complex—and beautiful—data visualizations. One of the reasons for its success was an extremely easy-to-use integrated development environment, or IDE. Banzi wondered if they could create similar software tools to code a microcontroller instead of graphics on a screen.

A student in the program, Hernando Barragán, took the first steps in that direction. He developed a prototyping platform called Wiring, which included both a user-friendly IDE and a ready-to-use circuit board. It was a promising project that continues to this day, but Banzi was already thinking bigger: He wanted to make a platform that was even simpler, cheaper, and easier to use.