Re: PIC16F88, PORTA strange behaviour

From: Paul Carpenter (paul$_at_pcserv.demon.co.uk)
Date: 12/02/04 

Date: Thu, 02 Dec 2004 16:36:10 +0000 (GMT)

On Thursday, in article
     <41af158c$0$566$e4fe514c@news.xs4all.nl>
     f.bemelmanx@xs4all.invalid.nl "Frank Bemelman" wrote:
>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:
>
>-, ,-, ,-, ,-, ,-
> '-----' '-----' '-----' '-----'
>-, ,---, ,---, ,---, ,---
> '- -' '---' '---' '---'
>
>If I generate the second signal on an output of PORTB,
>it all works okay.
......

When something works on one port but not on another for ANY micro
my suggestions are

        Check the port has been fully initialised for correct mode
          and o/p type.

        Check the connections on the pin if necessary open circuit
        the pin from the rest of the circuit and test again.

Looks suspiciously like something external to me though. 

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
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