Charlieplexing! for multiplexing LED’s at JEFFREY’s NOISE (j-noise)

Multiplexing is the process in which several channels are combined n such a manner that they can be transmitted through a single channel.

But what’s Charlieplexing?

Charlieplexing has almost the same idea. But here it is for driving LED’s from less number of pins .

So whats the use of this technique?

You can drive a large number of LED’s from a less number of pins. You might be saying that it is possible using a multiplexer.The answer is not wrong. But it will be hard for a huge number of LED’s.

See this example http://home.wanadoo.nl/electro1/avr/kitt.htm

See the explanation in Wikipedia

” Charlieplexing is an electronics technique developed by Charlie Allen (hence the name) at Maxim in which relatively few I/O pins on a microcontroller are used to drive a large number of LEDs.

With Charlieplexing, n drive pins can be used to drive n digits with n-1 segments each; in other words, n drive pins can be used to control n²-n LEDs. Traditional multiplexed display technique would take 2n drive pins to control n² LEDs.

Charlieplexing works by having the I/O pins alternate between driving digits and driving segments.”

See a sample circuit of controlling 56 LED’s through 8 pins