From owner-freebsd-current  Sat May  2 09:45:38 1998
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To: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
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In-reply-to: luigi's message of Sat, 02 May 1998 15:44:50 +0200.
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Subject: Re: Infrared ? (a simple experiment for laptop owners...) 
From: Jun-ichiro itojun Itoh <itojun@itojun.org>
Date: Sun, 03 May 1998 01:45:06 +0900
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>I have just verified on the libretto that if i do
>	hd -v /dev/ttyd1
>(after setting clocal and some speed in the range 1200..115200) it is
>receiving infrared signals from the TV/stereo remotes.
>using ppp on /dev/cuaa1 also returns the garbage generated by the
>remotes, whereas it does not seem to receive its own data (maybe
>receive is disabled while transmitting).
>Perhaps some laptop owners can put their machines back to back, run ppp
>at the same speed and see if, going in "term" mode, they can talk to
>each other ?

	I've tried that several years before.

	If you open IR port as RS232C serial port (/dev/ttyd1), it will
	behave as half-duplex serial port.  The port is strictly half-duplex,
	that is, if machine A and B send some bytes at the same time
	they will collide and junk byte will be received.

	Therefore, if you run ppp over IR port, you may be able to "ping"
	each other but you won't be able to perform ftp and other bulky
	data transfer.
	(by doing bulk data transfer the chance for the collision is very high)

itojun

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