On Tue, Feb 26, 2002 at 03:30:12PM +0800, Terence Ang wrote:
> Hi,
>     I will be receiving my batch of F628 soon, need to find out :-
>
> 1) If I use intrc can I still use the UART ???

The grief saving answer is no. The true answer is "maybe if the conditions
are right." Conditions being that the bit rate is slow enough and there
isn't drastic changes in temperature. As an experiment set your bit rate low
(like 300 BPS or thereabouts) and start transmitting bidirectional streams
between the two PICS. Then heat one and cool the the other. If the streams
screw up, then it's probably not going to work in practice. Keep lowering
the bit rate until it stabilizes even when one PIC is ice cold (slowing the
INTRC) and the other one is really warm (speeding INTRC up). If they can
work through that disparaity, then you'll probably be all right.


>
> 2) what will the be the maximum length of wire I can run between 2 F628 UART
> without any extra hardware.

Again the grief saving answer is "not far enough" ;-) This is an instance
where I'd think about throwing a couple of nickel components at the problem.
First I'd consider a couple of EIA485 transceivers. Then you can not worry
about distance. The other I'd consider is a current loop along the lines of
a MIDI OUT/MIDI IN. It takes little more than and jellybean transistor and
an optoisolator. Easily good for 5 meters at 31250 BPS.

You're going to have to decided how much crap you willing to take out of a
very shaky setup before starting to stabilize it.

Good Luck,

BAJ

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