I'd feel pretty nervous about connecting a processor pin directly to a
     wire 150 meters long.  At the very least, I'd want some resistance
     between the PIC and the cable, which would then limit your bandwidth,
     based on the capacitance of the cable.


______________________________ Reply Separator _________________________________
Subject: line driver
Author:  Anthony.nixon@ENG.MONASH.EDU.AU at internet
Date:    12/5/96 1:17 AM


Is it feasible to drive the LED of an optocoupler directly from
one of the PIC port pins configured as an output if the frequency
is less than 300Hz and the cable distance is about 150 meters?

I checked the result on a CRO and after passing the signal through a
Schmitt trigger inverter, and all seemed OK. I was wondering about
the loading effects on the PIC output pin.

Thanks for any help..

Tony


Just when I thought I knew it all,
I learned that I didn't.