Sparrow is a small DIY dev board based on an ATtiny13

This project is bringing AVR development to mobile devices. 

Created by Thomas Baum as an entry for the 2015 Hackaday Prize, Sparrow is a cloud-based microcontroller system driven by an ATtiny13A and configured using the stereo signal from a mobile device’s headphone jack. The Maker had set out to develop a web-based service for AVR programming with smartphones and tablets, in an effort to minimize some of today’s most common barriers.


“Smartphones and tablets are starting to replace traditional PCs. In the nurseries of the new generation mobile devices are already widely used. Even in developing countries mobile phones are found everywhere, but not everybody has their own PC,” Baum explains. “But are these devices suitable for development or electronic experiments? Try to write an app on a smartphone. In the area of microcontrollers, the problem lies in the closed systems. Interfaces are available but not uniform and not readily accessible from the browser.”


Baum notes that apps can be downloaded right from the Internet and directly uploaded to the controller via a browser that supports HTML5 audio tags. Those looking to develop their own programs can do so as well through an online assembler and C compiler. With Sparrow, the stereo signal represents the normal ISP-Interface and programming is accomplished through the audio jack.

“Apps can easily be shared by sound or simply be embedded into a video. In addition, there is no mobile device without a headphone output,” the Maker adds.


Typically speaking, the Sparrow is an uber mini PCB with an ATtiny13 MCU and a comparator LM339; however, once a Maker understands its inner workings, a majority of the solution can be built from scratch. This can be done by employing materials such as a wooden board with a few thumb tacks to hold the parts together, an old mobile phone battery, a little 6V bulb and a power switch from an old toy. Beyond that, the rest of the components could be found on any engineer’s workbench — four transistors BC548A, two LEDs, two momentary switches and a few resistors and capacitors. The most expensive piece, Baum jokes, is the $1 ATtiny13.

Interested in creating one of your own? The Maker provides a detailed breakdown of the build on his page here.

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