You could directly drive the IR LED, but typically you will want to use a modulated IR waveform to avoid interference from lights and daylight.  A simple example is shown in one of the original Basic Stamp application notes.  There is a link to it here:

http://www.pond.ie/ftp/stamp1_apps/ircomms.pdf

(I don't know why it's there, but that's where Google took me)

Basically your serial comms line gates the 40KHz waveform generated by the 555 on and off, or you could generate the 40KHz waveform in software in the PIC instead.  The GP1U52X shown is one of a number of different IR receiver/demodulators that can detect the 40KHz (or 38KHz) waveform and produce clean TTL output.

Be careful with the sense of your signals.  RS232 idle is a logical '1', but you probably want that to be represented by a physical '0' state, otherwise when the link is idle the LED will be on and the system will be consuming power.

I have played with this and had 9600bd comms across a room (about 4m) with good results.  You should probably add some error checking codes in your data stream so that the receiver can determine that the data was received correctly.

Hope this helps,

Andy

> Hello everyone,
>
>         I need to comunicate an 16F627 with another 16F627, using infrared
> technology (maybe or not IRDA compatible)
>         I was planning to use MAX3100 and/or MAX3120, but are to costly
for the
> project.
>         As a cheaper way of doing this, can I directly connect an infrared
led to
> TX and an infrared detector to RX on both devices ??
>         Is it right ? Another way of doing so ?
>
>       Thanks, Gabriel.-

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