From: Young Fan <youngcfan AT hotmail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Setting baud rate of serial port
Date: Fri, 09 Jul 1999 11:33:42 -0400
Organization: Nortel
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hello,

This is a follow-up of my previous posting ("Your help would be
appreciated..."). I am wondering how I can set the baud rate of the
serial port. I am using outp to send 1's and 0's to pin 4 of COM 2,
using outp((unsigned short)(0x2f8+4),(unsigned char)0x0F);. If I do not
set the baud rate, the signals are sent approximately every 1 to 3
microseconds. At 9600 baud, the duration of each 1 or 0 should be about
104 usecs. How would I set the baud rate? Is there anything else I would
need to do before sending the signals, such as initializing the port --
and then how would I do that? It's supposed to be 8 data bits, no
parity, 1 stop bit, but I'm already inserting the stop bit by myself.

I'm pretty sure this is wrong, but this is what I'm doing:

ioctl(0x2f8+4,(('X'<<8)+7),224);

...since this wouldn't work:

ioctl(0x2f8+4,TXSBAUD,_COM_9600);

...which I tried because this was in bios.h:

#define _COM_9600          224   /* 9600 baud. */

...and this was in sys/ioctl.h:

enum tty_ioctl {
  TXISATTY = ('X'<<8),    /* quick path for isatty */
  TXTTYNAME,		/* quick path for ttyname */
  TXGETLD,		/* get line discipline */
  TXSETLD,		/* set line discipline */
  TXGETCD,		/* get control disciplines */
  TXADDCD,		/* add control discipline */
  TXDELCD,		/* delete control discipline */
  TXSBAUD,		/* set integer baud rate */
  TXGBAUD,		/* get integer baud rate */
  TXSETIHOG,		/* set the input buffer limit */
  TXSETOHOG,		/* set the output buffer limit */
  TXGPGRP,		/* get p grp with posix security */
  TXSPGRP               /* set p grp with posix security */
};

Please help! Thanks in advance.