LED DOT MATRIX Help..!!

Discussion in 'The Projects Forum' started by blackintoxication, Nov 13, 2013.

  1. blackintoxication

    Thread Starter New Member

    Nov 13, 2013
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    Hello to everybody..!
    I am new to this forum,, Can anybody please help ,,
    I am trying display animations on 2 led dot matrices.. such that their rows are connected together (5x14) ,,
    now the problem is that i am unable to drive my dot matrix using uln2003a . I am using pic18f452 which is programmed with the animation. our teacher told us that to drive the dot matrix with uln, we would have to use it with pull up resistors. Without attaching the pull up resistors, and directly connecting the uln with the dot matrix , it powers up but does not switch due to which my leds are constantly on and there is no animation . when i connect the dot matrix with the pull up configuration, my leds dont even get powered up. i have written the code in a common anode configuration .( rows require logic 1 and columns require 0 logic ) our teacher also told that uln inverts the logic, so i have also tried to use an inverter(74hc04) before the uln to invert the code, but still my led dot matrix does not work . Please help. i have to submit the project by next tuesday.. :( .. what should i do..
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    969
    personally I think you should discuss the issues with your teacher.. Thats what they are (or should be ) there for.. Failing and getting back up is part of the learning process.

    I always laugh when I see.. "my teacher said this".. "my teacher said that" ... and then they come here for more help..
    Well what happened when you asked your teacher why this or that isn't working?
    oh you didn't.. why not?

    or at least post a schematic...
     
  3. blackintoxication

    Thread Starter New Member

    Nov 13, 2013
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    i had asked my teacher.. he said do it yourself.. ;/ troubleshoot it yourself.. find a way to do it yourself..! .. i am stuck.. :( .. it is working on proteus, but not when i implemented it on hardware..
     
  4. blackintoxication

    Thread Starter New Member

    Nov 13, 2013
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  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    You will have to connect the inputs to the ULns to the pic outputs, and connect the Led anodes to either the supply posative supply,using a series resistor, or to the other set of pic outputs, to make the leds come on make the input to the uln ic posative (1), if your using both sets of pic outputs set the other pic output to posative also.

    see diagram
     
  6. blackintoxication

    Thread Starter New Member

    Nov 13, 2013
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  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    well we can't check you physical wiring for you... Keep looking.
     
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