8*8*8 RGB Led Cube

Discussion in 'The Projects Forum' started by fistno, Apr 6, 2013.

  1. fistno

    Thread Starter New Member

    Apr 6, 2013
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    Hi there,
    I am working on a 8*8*8 RGB led cube. I took reference to;
    http://www.hownottoengineer.com/projects/rgb-led-cube.html by nick.
    I have build up my cube, led driver board using STP16 Led sink driver and controller, chipKIT UNO. However, I face a problem. After i connect all the wires and run the animation using chipkit, the led cube start to flicker and the leds cant light up brightly, and there isnt any animation at all.

    However, when i connect only a layer to my driver board, i am able to see that layer bright up with good animation. Same result for all 8 layers. Can anyone tell me y?

    I have check throught my circuit (build by nick). i don't find any thing wrong. I am using common anode led so i used PNP transistors. 1.5k ohm for pull up resistor, 100 ohm connect to PNP base, 1k ohmn connect to IC and 0.1uF capacitor to IC.

    I am using Bit Angle Modulation written on software base instead of PWM.
    The files are grab from http://www.hownottoengineer.com/down.html (this guy is great btw)

    I suspect my transistor cant support the circuit (sound impossible)

    Can anyone help me in this? thanks!!

    View attachment RGB LED CUBE.pdf

    View attachment PNP transistor.pdf

    View attachment STP16.pdf
     
  2. fistno

    Thread Starter New Member

    Apr 6, 2013
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    btw, i mean any problem that may occur eg. like short circuit, things that might happen as fault. I dont dun what i have left out.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    It seems like a lot of LEDs, is your power supply rated for enough amps to drive than all at once?

    Notice that the first link that you posted uses a 5 volt power supply rated at 12amps!
    8 x 8 x 8 = 256 LEDs. At, for example, 0.02 amps each, that is 5.12 amps.
    Since these are really RGB,that could be up to 3x the 5.12 amps. Or 15.36 amps. Again, assuming 20 maps per LED die.
     
    Last edited: Apr 6, 2013
  4. fistno

    Thread Starter New Member

    Apr 6, 2013
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    Hi, thanks for your reply.
    I am using laboratory power supply. So i believe it is fine.
    btw you just remain me of something.
    when i switch on the power supply, i only see the leds light up and flicker at 3.4 V ~ 3.8V, if go beyond the leds start to die out esp after 4V, i dun even see any lights at 5V.

    So does this means my circuit design got problem. And i dun quite understand what you mean by 20 maps die out. can you explain. Thanks btw.
     
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Sorry, auto-correct on the iPad.

    I meant to write, 20 mAmps per die. There are 3 LED dies in each of your 256 LED packages. One red, one blue and one green.

    It sounds like some type of short circuit. Your power supply may be going into protection mode as more and more current is flowing (as you boost the voltage).

    Finally, I have two laboratory power supplies. One rated at one amp with variable voltage. One at 20 amps with 5 or 12 volt output. It may be with another check. Also make sure you don't have your current limit set too low ( if your supply has that feature).
     
  6. fistno

    Thread Starter New Member

    Apr 6, 2013
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    thanks again.
    I will do a check on my driver board.
    i will post a video once i got my cube running. ha!
     
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