Date: Fri, 9 Sep 2005 08:23:10 +0800 From: "Paul Hamilton" <paulh@bdug.org.au> To: <freebsd-questions@freebsd.org> Subject: Re: C program to write to the com port - RESOLVED Message-ID: <053c01c5b4d4$a8ba8670$6600a8c0@w2k2>
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Hi,
Thanks to the patience and persistens of Giorgos, Garret and David, I =
now
have a *sample* program that will transmit 3 bytes of data (mini-ssc
protocol), via a serial port to a 8 channel servo controller board. I =
will
continue to develop this as needed. =20
DISCLAIMER: This is being posted for archival purposes, and no doubt =
can
use a lot of improvement!
-------------------------------------------------------------------------=
---
--------
/* Name: testssc.c =20
* compile with: gcc testssc.c -o testssc
* =20
* Your serial cable should be plugged into com port 1. =20
* You only need the pin 3 and pin 5 (DB9) plugged into the controller.
* The servo should be plugged into the first servo channel/port.
* This test program when run will move the servo from midrange,=20
* to position 01. This is for demonstrational use only.
* Tested with FreeBSD 5.4
* Paul Hamilton 8th Aug 2005
*/
#include <sys/time.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <termios.h> /*Originally it was termio.h*/
#include <stdio.h>
#include <unistd.h>
// Use serial port 0 (com port 1)=20
static char *opt_comport=3D"/dev/cuaa0";
int main(int argc, char **argv)
{
int fd;
struct termios options;
unsigned char buf[4];
// ok, lets try opening the com port
printf("Opening Com port: %s\n\n", opt_comport);
if((fd =3D open(opt_comport, O_RDWR | O_NOCTTY )) < 0)=20
{
printf("Problems opening %s\n", opt_comport);
return (-1);
}
// set the required com port parrameters
options.c_cflag &=3D ~CSIZE; /* Mask the character size bits */
options.c_cflag |=3D CS8; /* Select 8 data bits */
options.c_cflag &=3D ~PARENB; // set no parity
options.c_cflag &=3D ~CSTOPB; // set 1 stop bit
options.c_oflag &=3D ~OPOST; // Raw output
tcgetattr(fd, &options);
/*
* Set the baud rates to 9600...
*/
cfsetispeed(&options, B9600);
cfsetospeed(&options, B9600);
/*
* Enable the receiver and set local mode...
*/
options.c_cflag |=3D (CLOCAL | CREAD);
/*
* Set the new options for the port...
*/
tcsetattr(fd, TCSANOW, &options);
// ok, lets transmit our 3 bytes through com port 1
snprintf(buf,4,"%c%c%c%c",0xff,0x00,0x01,0);
printf("buf=3D%x,%x,%x,%x\n", buf[0],buf[1],buf[2],buf[3]);
if (write(fd, buf, 3) !=3D 3)
err(1, "write");
close(fd);
};
-------------------------------------------------------------------------=
---
--------
Cheers,
Paul Hamilton
PS. I have three books on programming in C winging their way to =
Australia.
I have a lot to learn :-)
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