Bruce Cannon wrote:
>
> Tjaart, regarding your schematic:
>
> > It converts +-12V (on the PC side) to -+5V (note the
> > inversion) on the micro side.
>
> Doesn't it convert +-12v to 0v-5v, unless RTS goes negative in which case
> the PIC sees -12v?

The PIC sees 0V, or 5V. With the 10k series resistors, it
wouldn't matter anyway, because the internal diodes will clip it.

>
> Could you tie the ground connection to pin 4 instead of pin 5 to get the
> legal voltage swing for transmitting to the PC?  (I mean if you adjusted the
> R values, set the control lines correctly at the PC end and go through
> diodes just in case).

You could. You could also use a driver chip.
I have never, ever, ever had a problem with the circuit on my page.
Why fix it if it ain't broke?

--
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