[Yann]’s DYPLED entry into this year’s Hackaday Prize isn’t very useful to most people. It’s a tiny module that connects to a 16-bit parallel bus, and displays a hexadecimal number on a few LEDs. It’s useful if you’re diagnosing a problem on a computer from 1982, but just barely. The real wonder here is how [Yann] is doing this cheaply and easily using some weird techniques and strange parts.
The display for this tiny device is an array of 36 LEDs, arranged into a set of five seven-segment displays. Homebrew seven-segment displays are cool, but how is he driving it? Not with a microcontroller, that’s for sure. Instead, [Yann] is using an old trick of using parallel memory to store the patterns of the seven-segment displays. This parallel memory comes in the form of a two megabit Flash chip, with the data inputs tied to the 16-bit input on the board and the data outputs connected directly to the LEDs. It’s a brute force approach, but it works.
There are a few additional features for this tiny board, including a switch to display a 16-bit bus in hexadecimal or decimal, signed or unsigned, and a pot to change how bright the LEDs are. The most amazing part is how [Yann] managed to fit all of this on a very, very small PCB. Most of that trick is due to using a thin, small TSSOP package for the Flash memory, but fitting this circuit onto a two layer board is amazing work, and a great entry for the Hackaday Prize.
