david@bdt.UUCP (David Beckemeyer) (08/07/89)
I'm trying to bring up a Motorola Computer System 8000 with HDB UUCP.
The problem is the tty driver doesn't seem to know how to send a BREAK.
The code which generates the break is:
genbrk(fn)
register int fn;
{
if (isatty(fn))
(void) ioctl(fn, TCSBRK, 0);
}
Nothing seems to happen when the above code is executed. The RS-232
hardware is a Motorola MVME332 8-port RS-232 board. The Unix version
is SYSTEM V/68 R2V2.2. Does anybody know how I can make this RS-232
board generate a BREAK?
Thanks.
--
David Beckemeyer (david@bdt.UUCP) | "I'll forgive you Dad... If you have
Beckemeyer Development Tools | a breath mint."
478 Santa Clara Ave. Oakland, CA 94610 | Bart - "The Simpsons"
UUCP: {uunet,ucbvax}!unisoft!bdt!david |csg@pyramid.pyramid.com (Carl S. Gutekunst) (08/23/89)
In article <109@bdt.UUCP> david@bdt.UUCP (David Beckemeyer) writes: >The problem is the tty driver doesn't seem to know how to send a BREAK. > > if (isatty(fn)) > (void) ioctl(fn, TCSBRK, 0); > >Nothing seems to happen when the above code is executed. Ugly. Assuming you have source -- it appears that you do -- the classic work- around from Version 7 UNIX should suffice. Simply drop the line baud to some very small number, like B50, transmit a NULL character, and then restore the speed. At 50 bps, one NULL gives you a nicely shaped 180ms pulse, which will do for a BREAK almost anywhere. On 4.3BSD, which has no timed BREAK, I've actually found this works better than the "normal" technique of forcing the line to a space state, waiting on an interval timer, then restoring. <csg>