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To: Don Wilde <Don@Silver-Lynx.com>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: serial data 
In-Reply-To: <3A32AD6D.6A4DFD79@Silver-Lynx.com> 
From: Chris Fedde <chris@fedde.littleton.co.us>
Date: Sat, 09 Dec 2000 16:12:16 -0700
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On Sat, 09 Dec 2000 15:08:45 -0700  Don Wilde wrote:
 +------------------
 | Hi, folks -
 | 
 | I'm trying to talk through a serial port, and freebsd's fighting me
 | every step of the way. (seems that way!)
 | 
 | I've got a microcontroller spitting out 2400 baud characters to ttyd1,
 | and not all that fast at that. My problem is that the getty process
 | doesn't seem amenable to control. I tried changing gettytab and ttys,
 | and I don't seem to have control of things. I can't get echo to stay
 | off, I can't get it to stay in clocal mode. My C program reading it is
 | just a simple getc/putc copy function like what's on page 3 of every C
 | book in sight.
 | 
 | Even poking with stty doesn't seem to affect it, at least not all the
 | time. Sometimes sending
 | 
 | 	stty -f /dev/ttyd1 clocal && ./inputprog </dev/ttyd1 
 | 
 | works, at least after I renice things so that the getty and my program
 | get all the CPU time, but other times it doesn't work. I'd like to know
 | why, if someone could tell me.
 | 
 | TIA! I'm not subscribed, so please cc: me.
 +------------------

There is a getty listening on the same port as your program?  You've set
your self up for a race condition.  You need to turn off the getty.
Then send init a hup.

chris


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