Author Topic: dual 16 channel or quad 8 channel demultiplexer?  (Read 1154 times)

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Offline blackbeardTopic starter

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dual 16 channel or quad 8 channel demultiplexer?
« on: October 03, 2010, 09:23:35 PM »
kind of a fuxord thing to look for but i'm trying to find a low chip count solution for my 4x4x4 led cube. can't find one no matter how hard i google. worst case i'll have to go with 2 separate chips which would kind of suck
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Offline Soeren

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Re: dual 16 channel or quad 8 channel demultiplexer?
« Reply #1 on: October 03, 2010, 10:52:28 PM »
Hi,

A Ácontroller is the cheapest and AFAIK only solution to that.
Regards,
S°ren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline billhowl

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Re: dual 16 channel or quad 8 channel demultiplexer?
« Reply #2 on: October 04, 2010, 12:13:30 AM »
you can reduce your pin count quite a bit using charlieplexing.  You can drive n(n-1) segments with charlieplexing.  So a 4x4x4 matrix would require only 9 pins.

http://forums.adafruit.com/viewtopic.php?f=11&t=10661
an instructable on making a 5x4x4 cube with Charlieplexing:
http://www.instructables.com/id/3D-LED-Charlieplex-Cube-from-Chrismas-Tree-Lights/

Offline madsci1016

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Re: dual 16 channel or quad 8 channel demultiplexer?
« Reply #3 on: October 04, 2010, 07:57:13 AM »
Only problem with charlieplexing is the duty cycle. 64 LEDs = 1/64 duty cycle, or something less if you get fancy, but still bad. LEDS under normal current circumstances can only take about 1/8 to 1/10 duty cycle before brightness drops significantly. To overcome that, most charlieplexing I've seen overdrives the LEDs, and if your code gets stuck, you start blowing pixels. And we are all assuming blackbeard is using single color LEDS. It could be RGB.

Any details of your project blackbeard?

 


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