PORTA.4 problem in PIC16F84A ?


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  1. #1

    Question PORTA.4 problem in PIC16F84A ?

    I don't know why porta.4 in pic16f84a can't be high , all other pins can go low or high but porta.4 only low.
    How I can solve this software or hardware ?

    here is my code :


    trisa=0
    porta=%11111

    main:
    goto main
    end

  2. #2
    Join Date
    May 2004
    Location
    NW France
    Posts
    3,648


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    Wink THE Porta.4 Trap ...

    Hi,

    Have a look to the '84 Datasheet ...

    Porta.4 is Well Known to be an OPEN COLLECTOR output ...

    You can use an external Pull up resistor, if you do not need too much current @ highstate.

    Alain
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

  3. #3


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    Question

    Oky I know this and I put a pull up resistor but this pin can't drive led so how I can do this ?

  4. #4
    Join Date
    Jul 2003
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    Default

    There's more than one way to power a LED - and that pin can SINK a LED quite happilly. Please study the PICs Datasheet and/or SEARCH the forum...

    http://www.picbasic.co.uk/forum/showthread.php?t=562

  5. #5


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    Exclamation

    Thanks Melanie for your details information
    but I don't know what is the objective for making this pin is the only pin who is open drain !

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