Microcontroller does not working

Discussion in 'Embedded Systems and Microcontrollers' started by ntsh1996, Jan 2, 2010.

  1. ntsh1996

    Thread Starter New Member

    Jan 2, 2010
    3
    0
    Hi guys I m new to the field. So help me.

    I had a small project with 16f877a MC. But its need to touch the ground pin of 7805 regulator to work MC properly.
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
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    Post your schematic
     
  3. ntsh1996

    Thread Starter New Member

    Jan 2, 2010
    3
    0
    schematic diagram of the power unit
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Wheres the PIC?
     
  5. Dragonblight

    Active Member

    Aug 19, 2009
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    I feel your power circuit is too complex and involved. Now that i'm done with opinion:

    Is Vdd your "pic power" and is Vss connected to ground?

    Also, do you actually need your mclr?
     
  6. ntsh1996

    Thread Starter New Member

    Jan 2, 2010
    3
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    pic power to Vdd & Vss ground.


    ya I need mclr
     
  7. Dragonblight

    Active Member

    Aug 19, 2009
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    I don't see anything obvious, but I would roll through your code and ask yourself if every last piece on that circuit is a necessity. I don't personally see why you need the LED and diodes, but I don't know what your trying to rock on the other side of that pic.
     
  8. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    the led should light when you have power, I like that, keep it. Use a meter or a scope to measure the volatage on the pic pins esp. power and make sure they are correct. Does the pic have a clock signal ( look with a scope ). If you are on a bread board using a crystal do not go above 4 meg hz unless you do not mind fiddling around to make sure the clock is running.

    Use a program so dog simple that you are sure it is ok.

    Post more of your project.
     
  9. AllVol

    AAC Fanatic!

    Nov 22, 2005
    55
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    Sounds like a simple oscillator problem.... lack of crystal, resonator or RC, or be device is correctly set in configuration statment.
     
  10. Dragonblight

    Active Member

    Aug 19, 2009
    35
    0
    I agree. totally
     
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