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### Topic: Charlieplexing + Arduino Uno's 20 pins = Powering 380 LEDS ? (Read 2347 times)previous topic - next topic

#### mixania

##### Sep 14, 2012, 03:34 pmLast Edit: Sep 14, 2012, 03:44 pm by mixania Reason: 1
Hi Arduino Forum, Hi guys!  :~

Recently I've been looking on Internet for some ideas to start with my project. I wanted to make a LED cube in the beginning but then "Charlieplexing" got my attention. I'm not sure if this technique exactly is used in making LED cubes (or is it?) but "Charlie" made me want to make a controllable LED screen with few Arduino pins. I'm Using an Arduino Uno R3. I have a breadboard but I understand that its awkward to make something big with it. But thats not the question.

The Question is if it's possible to drive 380 LEDs with just 20 pins (14 DigitalPins + 6 AnalogPins) on and Arduino Uno without having any power problems (I mean to much current consumption or whatever). If yes then what are the options? How to maximize the power? I mean of course it would have enough power to light on LED at a once, but how about 100 at once? 200? 300? And 380? Doesn't it need additional power supply?

The formula of the maximum amount  LEDs usable per pin is: x2 - x
Where x is the amount of pins and the result of how many pins it's possible to hook up.
Plug in 20 and thats it! The Answer is 380 LED's! Cool! Now Is the Arduino thought enough?

OK, if thats possible then how to make 380 LEDs organized? I mean a circuit board is an essential, right? No breadboard is good enough for fitting 380 LED's. But would it be possible to order such a dense circuit board?

http://www.instructables.com/id/Creating-a-charlieplexed-LED-grid-to-run-on-ATTiny/ - Instructable

#### JoeN

#1
##### Sep 14, 2012, 06:28 pmLast Edit: Sep 14, 2012, 06:56 pm by JoeN Reason: 1

I mean of course it would have enough power to light on LED at a once, but how about 100 at once? 200? 300? And 380? Doesn't it need additional power supply?