Seven-Segment… Input?

Seven-segment displays are, by their very nature, output devices. However, as seen with this clever input hack, they apparently don’t have to be. This wooden device consists of three sets of sliders that turn segments "on" and "off" based on their physical position. The left segment slides to modify the two left vertical segments, the middle actuates the middle three segments, and the right slider controls the two right vertical segments.

The concept might work as a fun children’s toy, but what makes it electro-magical is that the sliders have magnets strategically embedded down their length. These magnets are picked up by seven Hall effect sensors, and this data is sent to an HC165 eight-bit shift register to sense the entire digit on display. These units can be daisy-chained together for reading of multiple digits, and data is passed on to a microcontroller for processing. While actually decoding this input might seem cumbersome, creator Dave Ehnebuske developed an Arduino library to help with the task.

Build-wise, modules are formed out of stacked wooden segments, which appear to have been cut out (and selectively darkened) on a laser cutter. Hall effect sensors, resistors, and wires are arranged in a dead-bug style. If one wanted to take it further, a 3D-printable body would be another option, and a PCB could potentially simplify the wiring.

It’s quite an interesting project, both as a concept and stylistically, and hopefully it will serve as inspiration for other projects. Perhaps we’ll see a seven-segment display that’s able to work as both an input and output device at the same time!