You say you only want the PC to comunicate to the PIC. If you want level
conversion (sort of) the smallest and cheapest is to go with the 1489. 14
pin dip or soic and about 39 cents. No hassle with caps.

Rogerio





tbrisebois@FPMX.COM on 06/05/98 10:29:09 AM

Please respond to PICLIST@MITVMA.MIT.EDU

To:   PICLIST@MITVMA.MIT.EDU
cc:    (bcc: Rogerio Odriozola/MTY/TVA/Dataflux)
Subject:  Re: RS-232 using PIC 16F84 or 12C509




You can use the MAX206 which is offered from Maxim which is an 24 pin
SSOP which is very small and only about $2.00.
> > I know this has been mentioned before, I looked at the archive and I
don't
> have lots of free time on my hands. All I need to know is what will it
take
> to communicate to a PIC with a PC. I just need to transmit signals to the
> PIC via PC. I DON'T need the PIC to talk to the PC. Do I need a rs-232 ic
> or what?? I'm new to this and am not sure what it will take. Any advise
and
> suggestions would be apprecited!!!!
>
>
> You can get there with just connecting the pic directly to the PC. If you
> do, the logic 1 in the pic output is a zero to the PC.
> I've written bit-banger full duplex com for the '84. In my case, we used
a
> buffer transistor, but it wasn't strictly needed.
> If you want a little protection on the port pins, a 470 ohm resistor
would
> be a good idea.
> Any solution that only sends +5 and ground is violating the spec, but the
> 1489 receivers (maybe the most popular 232 Rx chip
> on the planet) only sense + and ground.  The '88 transmitter sends +/-V
as
> per spec.
>
> A maxim chip will get you there, but it's large, and expensive.
>
> The soft uart routines have been done to death, so I imagine you've got
that
> code already.
>
>
Todd Brisebois
Engineering
Fitel-Photomatrix
tbrisebois@fpmx.com   (613)228-9695  ext.229