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Charlieplexing (with video!)

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Charlieplexing (with video!)

Unread postAuthor: Los Frijoles » Sun Aug 12, 2007 2:25 pm


Using the extremely complicated Charlieplexing method and the tri-state I/O pins of a microcontroller (wow big words), I got a Charlieplexing circuit working. I did this when I was randomly board and was googleing Charlie on the web (Charlie is my frog's name...). I randomly had 12 white LEDs sitting around my workbench along with some 47 ohm resistors (used for current limiting).

Basically, Charlieplexing uses the uni-directional and voltage drop properties of LEDs to multiplex LEDs very efficiently. Using only 4 I/O pins, I can control 12 LEDs. 8 pins will give me 56 LEDs, 9 pins gives me 72, etc. The exact formula is LEDs = (N Pins) * (N pins)-1. The only problem is that the refresh rates get rather low once you get 12 LEDs running at the same time (each has to be lit individually to give the effect of the whole bank on) so I am not going to pursue it for making displays and stuff.

What do you guys think?
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Los Frijoles
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Unread postAuthor: potatoflinger » Sun Aug 12, 2007 7:59 pm

That looks pretty cool!
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