Many thanks Peter, your help was invaluable. I didn't know this bug.
Let me post your message in the message board. It could save hours of work
to others
Gustavo

----- Original Message -----
From: "Peter Dannegger" <danni@specs.de>
To: "gustavo martin" <dbup@ciudad.com.ar>
Sent: Monday, April 22, 2002 4:15 AM
Subject: Re: [8052.com message board]


> Hi Gustavo,
>
> >
> >void timer1(void) interrupt 3
> > {
> >
> > ET1=0;
> > TL1=0xBA;
> > TH1=0xFD;
> > ET1=1;
> > P1_1=~P1_1;
> >
>
> the last line seems the problem.
> This bug was known many years, so I wonder, why it was still present.
>
> Any read modify write instruction on P1 may influence also P1.0, if the
> T2 overflow
> occur simultaneous.
> So, if possible, use the remaining P1 pins as inputs only.
>
> Please ask Atmel, why five years not enough to correct this bug.
>
>
> Peter