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CardboardGuru
09-08-2007, 12:41 AM
I don't know what microcontroller they used for this LED cube project, but it's very doable with a propeller.

uk.youtube.com/watch?v=lFDcdN47V5s (http://uk.youtube.com/watch?v=lFDcdN47V5s)

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Help to build the Propeller wiki - propeller.wikispaces.com (http://propeller.wikispaces.com)

Beau Schwabe (Parallax)
09-08-2007, 01:04 AM
With 6 level's that would make a cool LED clock.



P.S. I believe that Bre meant a 470 Ohm resistor rather than a 47 Ohm resistor.

470 Ohms (Yellow, Purple, Brown)·sounds about right if you are using a 5V supply and the LED's are roughly 7mA

...use a 220 Ohm resistor (Red, Red, Brown) if you are driving this from a 3.3V Propeller.





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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 9/7/2007 7:16:53 PM GMT

Graham Stabler
09-08-2007, 01:22 AM
There was talk about a different kind of multiplexing (called someonesname-plexing) a few weeks ago that would allow many more leds than the expected to be lit from a given number of outputs, considering that the propeller has 32 IO you could make a seriously cool cube and have leds chasing each other around like flies. I'd use smt leds glued to mylar sheets and connected up with super fine magnet wire, mount in a frame and "jobs a good un"

Graham

Graham Stabler
09-08-2007, 01:27 AM
It was charlieplexing and allows n^2-n leds to be controlled so thats 992 just short of a 10X10 cube. Not quite as good as I imagined (forgot about the cube bit!)

Graham

Beau Schwabe (Parallax)
09-08-2007, 01:34 AM
I don't know if it's "charlieplexing" (...I'd never hear that term before this forum) or what, but if you implemented polarity reversal rather than just HIGH/LOW to control the LED's, you can effectively double the amount of LED's you could control·with the same·number of I/O lines you would use otherwise.

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Graham Stabler
09-08-2007, 01:38 AM
Its this:

www.maxim-ic.com/appnotes.cfm/appnote_number/1880 (http://www.maxim-ic.com/appnotes.cfm/appnote_number/1880)

Beau Schwabe (Parallax)
09-08-2007, 01:51 AM
Yeah ok...

This scheme must be driven with open collector·HIGH for each segment, and then driven·LOW for the Common Cathode (CC)·character of interest in order for it to work properly.



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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Harrison.
09-08-2007, 01:57 AM
The processor is an Atmel ATtiny2313. The minipov kit schematics are at: http://www.ladyada.net/make/minipov2/hardware.html .

Post Edited (Harrison.) : 9/7/2007 7:32:21 PM GMT