Re: minicom serial output

From: Juhan Leemet (juhan_at_logicognosis.com)
Date: 07/22/04 

Date: Thu, 22 Jul 2004 05:34:31 -0200

On Thu, 22 Jul 2004 02:40:56 +0100, anonymous coward wrote:
> My device is very simple and only uses ground, TD and RD. All the other
> lines are left floating. I wonder whether this could be part of the
> problem, even though I turned off both software handshaking and
> hardware handshaking.

I was going to ask how you had the wiring setup. Personally, I would try
to use some of the modem control signals (to the computer), such as DCD
(data carrier detected) and CTS (clear to send) etc. I don't remember what
they are, but you can look them up. If you've left them floating they
could be anything. With some logic they do eventually float up (or down),
but it may depend on internal wiring and/or noise, etc. Unlikely, but
maybe. The hardware serial I/O chip in the computer might have its send
"disabled" or "held off" (e.g. by CTS not being asserted). You can put
stuff into the queues and they'll get put into the hardware buffers, but
then they'll fill up and wait (maybe forever).

I see you (accidentally?) got it to work. Good stuff. I would still assert
those signals, though. Might be good to do it on your devices, too? Then
they would have "standard" (say 9-pin PC connections, which are really not
RS-232 standard, but have become defacto standards). 

-- 
Juhan Leemet
Logicognosis, Inc.

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