Date: Wed, 15 Jan 2003 13:20:42 +0200 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Paul Hamilton <paul@computerwest.com.au> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: How do I monitor the serial CTS line via C programmatically? Message-ID: <20030115112042.GA26041@gothmog.gr> In-Reply-To: <AGEHIFHGNEMPFNCPLONMCEMNEBAA.paul@compwest.com.au> References: <AGEHIFHGNEMPFNCPLONMCEMNEBAA.paul@compwest.com.au>
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On 2003-01-15 18:26, paul@computerwest.com.au (Paul Hamilton) wrote:
> I have been trying to monitor the serial CTS line. I would like to
> log the fact that the CTS has changed state (active/non-active).
>
> I have been trying to adapt some Linux programs, but am having
> problems with adapting the POSIX TIOCMGET function.
>
> Is there a FreeBSD way?
You'd have to poll using ioctl(fd, TIOCMGET, &int) and detect CTS
changes by checking the TIOCM_CTS bit in the returned value. The
following (untested) sample program should be easy to adapt to your
needs. When TIOCM_CTS changes from on to off or vice versa, the
program should print the change.
#include <sys/ioctl.h>
#include <stdio.h>
#include <unistd.h>
int
main(void)
{
int bits;
int last;
if (ioctl(0, TIOCMGET, &bits) == -1)
err(1, "ioctl");
last = bits & TIOCM_CTS;
printf("CTS %s.\n", last ? "on" : "off");
while (1) {
if (ioctl(0, TIOCMGET, &bits) == -1)
err(1, "ioctl");
if ((last ^ (bits & TIOCM_CTS)) != 0) {
last = bits & TIOCM_CTS;
printf("CTS %s.\n", last ? "on" : "off");
}
usleep(100000);
}
return (0);
}
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