For years, the humble Arduino microcontroller—a cheap, open source, midnight-blue circuit board emblazoned with a tiny white infinity loop—has been a favorite tool of the DIY electronics crowd.

As electronic devices got more complicated in the past few decades, it became increasingly difficult and expensive to tinker with hardware. The 1970s garage engineers who built their own computers ...

Raspberry Pi has received the lion’s share of attention devoted to cheap, single-board computers in the past year. But long before the Pi was a gleam in its creators’ eyes, there was the Arduino.