What is the proper way to do this?  It seems that if you set the PORT value
high before setting the TRIS to output that it will get overwritten by the
pin value and if you set the TRIS to output first that the PIC will briefly
try to pull the pin low before taking it high.

Thanks
Nick


----- Original Message -----
From: "Reelf Monsees" <bam-mon@EWETEL.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, January 09, 2004 2:15 AM
Subject: Re: [PICLIST] [PIC:] RS232 Driver IC Supply Noise


Well, had the same problem with the max3221, it produced so much noise
that AD-sampling on the same board was impossible. No, decoupling etc.
was alright, just in case you might ask ...
The only solution was to switch the max3221 off while the ADC are
active.

regards,
     Reelf

"Jan-Erik Soderholm XA (TN/PAC)" schrieb:
>
> James Nick Sears wrote :
>
> > I replaced the max3221 and the supply is still noisy as all
> > hell but the false !INVALID signals are not occurring.
> > Probably if I add some extra capacitance now I'll be ok
>
> Perhaps you should have put a "driver" between the PIC pin
> and the power supply of the MAX chip. Everything looks like
> the MAX has a varying current drain depending on what it's
> currently "doing". If it's feeding current out on the RS232
> line, the charge pump have to work a little harder for a
> short while. Or put something like 100uf as a reservoar
> that is charged through current limiting resistor of around
> 200 ohms from the PIC pin. Or put a simple FET in between
> and switch the MAX chip directly to 5V. Or an ULN type of
> driver chip.
>
> >
> > By the way, I think I first heard about it on this list but
> > if anyone hasn't tried Chipquik removal solder yet it is
> > great stuff.  I paid $18.50 for my kit and it has already
> > paid for itself several times over and I probably haven't
> > used 5% of it.
>
> Any URL that shows what this is ?
>
> Regards
> Jan-Erik.
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

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