Re: PIC16F88, PORTA strange behaviour

From: Mark A. Odell (odellmark_at_hotmail.com)
Date: 12/02/04

  • Next message: Frank Bemelman: "Re: PIC16F88, PORTA strange behaviour" 
    Date: 2 Dec 2004 13:53:54 GMT

    "Frank Bemelman" <f.bemelmanx@xs4all.invalid.nl> wrote in
    news:41af158c$0$566$e4fe514c@news.xs4all.nl:

    > Strange problem:
    >
    > Setting an output low on PORTA, causes another output
    > on PORTA to go low too.
    >
    > Below is the entire program. It should generate two signals:
    >
    > ---, ,---, ,---, ,---, ,---
    > '---' '---' '---' '---'
    > -, ,---, ,---, ,---, ,---
    > '- -' '---' '---' '---'
    >
    > But instead gives this:
    >
    > -, ,-, ,-, ,-, ,-
    > '-----' '-----' '-----' '-----'
    > -, ,---, ,---, ,---, ,---
    > '- -' '---' '---' '---'

    Are you doing this without delays in the inter-port pin state changes?
    That is, fast? If so, you've hit the fun errate of read-modify-write on a
    port. Try using a pin on port A and a pin on another port, the problem
    should go away. Microchip has a good description of this problem in one of
    the PIC documents. I can't find it right now. It may have been in the Q&A
    section of the PIC18 reference. Good luck. 

    -- 
- Mark ->
--
  • Next message: Frank Bemelman: "Re: PIC16F88, PORTA strange behaviour"

    Relevant Pages

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