12F675 output dependency


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  1. #1
    Join Date
    May 2007
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    Default 12F675 output dependency

    I'm using PIC12F675. I have problems with digital outputs. It seems, that they are dependent to eachother.

    DEFINE OSC 4 ' 4MHZ
    ADCON0 =0 ' No analog inputs
    ANSEL = 0
    VRCON = 0
    TRISIO = %00000000 ' Only digital outputs

    loop:
    GPIO.0 = 1 'LED 0
    Pause 1000

    GPIO.2 = 1 'LED 2
    Pause 1000

    GPIO.1 = 1 'LED 1
    PAUSE 1000

    goto loop
    end

    The outcome of this code is following:
    LED 0 turns on, pause,
    LED 0 turns off and LED 2 turns on, pause,
    LED 1 turns on, pause,
    LED 1 turns off and LED 0 turns on.
    etc.
    LED 2 remains all the time switched on. It seems, that GPIO.2 is somehow independent, and GPIO.0 and GPIO.1 are dependent. Why is it so? What I'm doing wrong? As much as I've read about it, all digital outputs should be independent.

    Kristjan

  2. #2
    Join Date
    Sep 2004
    Location
    montreal, canada
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    How about if you add CMCON=7 ?

    sure i miss something around OPTION_REG.5=0 or something like that... i feel lazy today...
    Last edited by mister_e; - 4th May 2007 at 23:57.
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  3. #3
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    Yep. It works now Tnx.
    Stupid question maybe, but why CMCON has to be 7 not 6 or 5? If I want to use also some analog inputs, then how CMCON has to be set? I'm also trying to find out the answer by myself.

  4. #4
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    Look at section 7 (if my memory serves me well) of your datasheet (analog comparator section) there, should should find a table with the possible settings.

    Analog comparator and analog to digital converter are two different animals...
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  5. #5
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    Tnx. I got my problem solved

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