Linux C 串口

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <stdlib.h>
#include "Serial.h"

int main (void)
{
    int fd;
    int nread, i;
    char buff[] = "Hellon";
    if ((fd = open_port (fd, 1)) < 0)
    {
        perror ("open_port error");
          return;
    }

    if ((i = set_opt (fd, 115200, 8, 'N', 1)) < 0)
    {
        perror ("set_opt error");
          return;
    }

    printf ("fd=%dn", fd);

    while (1)
    {
        nread = write (fd, buff, 5);
          printf ("nread=%d,%sn", nread, buff);
          sleep (1);
    }
    close (fd);
    return;
}

#ifndef SERI_H
#define SERI_H

int open_port (int fd, int comport);

int set_opt (int fd, int nSpeed, int nBits, char nEvent, int nStop);

#endif

int set_opt (int fd, int nSpeed, int nBits, char nEvent, int nStop)
{
    struct termios newtio, oldtio;
    if (tcgetattr (fd, &oldtio) != 0)
    {
        perror ("SetupSerial 1");
        return -1;
    }
    bzero (&newtio, sizeof (newtio));
    newtio.c_cflag |= CLOCAL | CREAD;
    newtio.c_cflag &= ~CSIZE;

    switch (nBits)
    {
     case 7:
            newtio.c_cflag |= CS7;
            break;
     case 8:
            newtio.c_cflag |= CS8;
            break;
    }

    switch (nEvent)
    {
     case 'O':
            newtio.c_cflag |= PARENB;
            newtio.c_cflag |= PARODD;
            newtio.c_iflag |= (INPCK | ISTRIP);
            break;
     case 'E':
            newtio.c_iflag |= (INPCK | ISTRIP);
            newtio.c_cflag |= PARENB;
            newtio.c_cflag &= ~PARODD;
            break;

        case 'N':
            newtio.c_cflag &= ~PARENB;
        break;
    }

    switch (nSpeed)
    {
     case 2400:
            cfsetispeed (&newtio, B2400);
            cfsetospeed (&newtio, B2400);
            break;
     case 4800:
            cfsetispeed (&newtio, B4800);
            cfsetospeed (&newtio, B4800);
            break;
     case 9600:
            cfsetispeed (&newtio, B9600);
            cfsetospeed (&newtio, B9600);
            break;
     case 115200:
            cfsetispeed (&newtio, B115200);
            cfsetospeed (&newtio, B115200);
            break;
     case 460800:
            cfsetispeed (&newtio, B460800);
            cfsetospeed (&newtio, B460800);
            break;
        default:
            cfsetispeed (&newtio, B9600);
            cfsetospeed (&newtio, B9600);
            break;
    }

    if (nStop == 1)
        newtio.c_cflag &= ~CSTOPB;
    else if (nStop == 2)
        newtio.c_cflag |= CSTOPB;
    newtio.c_cc[VTIME] = 0;
    newtio.c_cc[VMIN] = 0;
    tcflush (fd, TCIFLUSH);
    if ((tcsetattr (fd, TCSANOW, &newtio)) != 0)
    {
        perror ("com set error");
        return -1;
    }

    printf ("set done!n");
    return 0;
}

int open_port (char *dev )
{

    fd = open (dev, O_RDWR | O_NOCTTY | O_NDELAY);
    if (-1 == fd)
    {
        perror ("Can't Open Serial Port /dev/ttySAC0");
        return (-1);
    }
    else
        return fd;
}