LED Life And Charlieplexing

Yesterday, we featured [Andrew]’s orientation aware camera. We want to highlight another one of his projects: LED Life. It’s a 6×5 LED matrix playing Conway’s Game of Life. He used the low power MSP430 like our e-paper clock. The best part of the writeup is his explanation of how Charlieplexing works. Microcontroller GPIO pins generally have three possible states: output high, output low, and input. This combined with the directional nature LEDs and some creative wiring means you can run a large matrix of individually addressable LEDs with just a few IO pins. Instead of just flipping the IO pins on and off you change their assigned state. Have a look at [Andrew]’s site for some great illustrations of how the system works. A video of his LED Life board is embedded below.

[flickr video=2606304451]

7 thoughts on “LED Life And Charlieplexing

  1. This charlieplexing is very interesting, only drawback seems to be that he only turns on one LED at a time. Of course (he mentions it) he could lit up more than one at a time, but probably this will soon draw too much power. Amplifier stage would be necessary then (and a more complex one than for normal matrix multiplexing), killing the simplicity of the design.

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