如何实现在LINUX系统上直接控制串口RTS信号电平

只看该作者 · 2007-12-13 14:13

如何实现在LINUX系统上直接控制串口RTS信号电平，使RTS信号有效或无效
现在需要直接控制这个信号来控制一个设备。哪位知道请告诉一下非常感谢！最好给个例子，急！！在线等啊

只看该作者 · 2007-12-13 22:53

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#define false 0
#define true 1

void sighandler ( int status );
int setup_com(int fd);

int wait_flag = false;
/* set up the options for serial port */

int fd;

int setup_com(int fd)
{
    struct termios options;

    tcgetattr(fd, &options);
    /*
     * Set the baud rates to 115200...
     */
    cfsetispeed(&options, B57600);
    cfsetospeed(&options, B57600);

    /*
     * Enable the receiver and set local mode...
     */

    options.c_cflag |= (CLOCAL | CREAD);

    /*
     * Set global options.
     */
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~PARODD;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;

    /* set the input options */

    options.c_iflag &=~(IXON | IXOFF | IXANY);
    options.c_iflag &=~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    //options.c_lflag |= ISIG;

    /* set the output options */
    options.c_oflag=0;// &= ~OPOST;

    /* set the timeout options */
    options.c_cc[VMIN]  = 0;
    options.c_cc[VTIME] = 10;

    tcsetattr(fd, TCSANOW, &options);

    return 1;

}

void sighandler ( int status )
{
    printf("receive data. ");
    wait_flag = true;
}

int main(int argc, char **argv)
{

      int nbytes,i;
      unsigned char *buffer;
      int ctrlbits;

      struct sigaction action;

      fd = open("/dev/ttyS2", O_RDWR | O_NOCTTY | O_NDELAY );

      if (fd == -1)
          {
            perror("open_port: Unable to open /dev/ttyS0 - ");
            return -1;
          }
      else
          {

                action.sa_handler = sighandler;
                action.sa_flags = 0;
                sigaction(SIGIO, &action, NULL);

                fcntl(fd, F_SETOWN, getpid());

                fcntl(fd,F_SETFL,FASYNC);
                //fcntl(fd, F_SETFL, 0);

                  setup_com(fd);

                 //receive enable
                ioctl(fd,TIOCMGET,&ctrlbits);

                ctrlbits |= TIOCM_RTS;//set enable
                //ctrlbits &= ~TIOCM_RTS;//disable

                ioctl(fd,TIOCMSET,&ctrlbits);


                  while(1)
                  {
                      if (wait_flag == true )
                          {

                            if((nbytes = read(fd, buffer, 5)) > 0)
                      printf("nbytes =0x%x. ",nbytes);
                      for(i=0;i<nbytes;i++)
                        {
                            printf("the receive data =0x%x. ",buffer);
                        }

                                printf("send data. ");
                          //send enable
                                    ioctl(fd,TIOCMGET,&ctrlbits);
                                          ctrlbits &= ~TIOCM_RTS;//send enable
                          ioctl(fd,TIOCMSET,&ctrlbits);

                                          buffer[0]+=1;

                                          if((nbytes=write(fd, buffer, 1))>0);
                                          sleep(1);

                                        //receive enable
                                    ioctl(fd,TIOCMGET,&ctrlbits);
                                          ctrlbits |= TIOCM_RTS;//send enable
                          ioctl(fd,TIOCMSET,&ctrlbits);
                            wait_flag = false;

                          }

                  }

                close(fd);
            }

    return 0;
}

只看该作者 · 2007-12-14 08:58

问题已经解决了
谢谢freeworld

如何实现在LINUX系统上直接控制串口RTS信号电平

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