PIC16F88 Interfacing with LED MATRIX

Discussion in 'The Projects Forum' started by Mohit Mayank, Mar 3, 2015.

  1. Mohit Mayank

    Thread Starter New Member

    Mar 3, 2015
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    Hi, I am trying to interface PIC16F88 with 8x8 LED MATRIX, using 4017 and ULN2803. My aim is to built a binary clock, and before directly jumping to hardware I thought of doing the simulation on Proteus 8.1 .
    So I interfaced the components and wrote the Embedded C program for the binary clock and tried to run the simulation on my computer, which as you have already guessed, didn't worked.

    The main problem is ULN2803, it is not sinking current(i.e. there is no current flow on the right side of ULN2803)
    [​IMG]
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    Can Anyone please look at my circuit and tell me whats the problem there.
    Thank you.
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    You have no ground connection on pin 9.
     
  3. Mohit Mayank

    Thread Starter New Member

    Mar 3, 2015
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    of ULN?? But it is not showing, so I thought it was automatically connected to ground. Am I wrong?
     
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    the Uln wont work without a ground connection to 0v.
     
  5. Mohit Mayank

    Thread Starter New Member

    Mar 3, 2015
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    Hey, I am using Proteus, and when I click on ULN2803 and see the hidden pins, its says pin9 is connected to GND. Is it enough? If not then can you please guide me, to fix this.
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    i dont use simulation software, i build circuits to work on PCBs, the ic doesn't have a power supply, so i cant see how it can work?
     
  7. absf

    Senior Member

    Dec 29, 2010
    1,493
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    Just add resistor pack like the attached to the output of ULN and set the property to 'digital' then it should work.

    Allen

    matrix_2 AAC.PNG
     
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  8. Flare_Guy

    New Member

    Nov 18, 2012
    13
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    Pin 10 (COM) needs to be tied to V+
    upload_2015-3-3_22-49-50.png
     
  9. Mohit Mayank

    Thread Starter New Member

    Mar 3, 2015
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    ULN is finally working, thank you
     
  10. #12

    Expert

    Nov 30, 2010
    16,355
    6,852
    The differences between simulating and real circuits seems so very strange!
    A, "real" circuit does not need a, "respak-7" (because R1 to R8 take care of that) but the ULN package needs a ground.
    In simulation, you have to add unnecessary resistors and the grounds are, "provided"?
    I'm so old that this makes my head hurt.
     
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