linux串口编程

下面是关于最近自己的一个串口编程程序：

/************************************
version:0.1
date :12/01/2010
author :yangchar
************************************/

#include <stdio.h> /* Standard input/output definitions */
#include <stdlib.h> /* Standard lib */
#include <string.h> /* String function definitions */
#include <unistd.h> /* UNIX standard function definitions */
#include <fcntl.h> /* File control definitions */
#include <errno.h> /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */
#include <sys/types.h>
#include <sys/select.h>
#include <sys/stat.h>

#define DEBUG 1
int open_port(const char *dev_name)
{

        int fd,val; /* File descriptor for the port */


        fd = open(dev_name, O_RDWR | O_NOCTTY | O_NDELAY);
        if (-1 == fd)
        {
          perror("open_port: Unable to open tty " );
        }
        else
        {
    
        if(DEBUG)
                    printf("The %s is opened \n",dev_name);
        }


           if( (val=fcntl(fd, F_SETFL, 0))< 0)
     perror("fcntl failed");
    else
    {
        if(DEBUG)
            printf("The fcntl is %d \n",val);
    }

    
    if ( isatty(fd) == 0 )
            perror("This is not a tty device ");
    else
    {
        if(DEBUG)
            printf("isatty success! \n");
    }

        return (fd);
}

    
int set_port (int fd , int nSpeed , int nBits , char nEvent , int nStop )
{
    struct termios new_ios,old_ios;

    if ( tcgetattr ( fd , &old_ios ) !=0 )
        perror("Save the terminal error");
    else
    {
        if(DEBUG)
            printf("Save the terminal success \n");
    }

    bzero( &new_ios , sizeof( struct termios ));
    new_ios=old_ios;
    new_ios.c_cflag |= CLOCAL |CREAD ;
    new_ios.c_cflag &= ~CSIZE ;

    switch (nBits)
    {
        case 5:
            new_ios.c_cflag |=CS5 ;
            break ;
        case 6:
            new_ios.c_cflag |=CS6 ;
            break ;
        case 7:
            new_ios.c_cflag |=CS7 ;
            break ;
        case 8:
            new_ios.c_cflag |=CS8 ;
            break ;
        default:
            perror("Wrong nBits");
            break ;
    }
    
    switch (nSpeed )
    {
        case 2400:
            cfsetispeed(&new_ios , B2400);
            cfsetospeed(&new_ios , B2400);
            break;
        case 4800:
            cfsetispeed(&new_ios , B4800);
            cfsetospeed(&new_ios , B4800);
            break;
        case 9600:
            cfsetispeed(&new_ios , B9600);
            cfsetospeed(&new_ios , B9600);
            break;
        case 19200:
            cfsetispeed(&new_ios , B19200);
            cfsetospeed(&new_ios , B19200);
            break;
        case 115200:
            cfsetispeed(&new_ios , B115200);
            cfsetospeed(&new_ios , B115200);
            break;
        case 460800:
            cfsetispeed(&new_ios , B460800);
            cfsetospeed(&new_ios , B460800);
            break;
        default:
            perror("Wrong nSpeed");
            break;
    }

    switch (nEvent )
    {
        case 'o':
        case 'O':
            new_ios.c_cflag |= PARENB ;
            new_ios.c_cflag |= PARODD ;
            new_ios.c_iflag |= (INPCK | ISTRIP);
            break ;
        case 'e':
        case 'E':
            new_ios.c_iflag |= (INPCK | ISTRIP);
            new_ios.c_cflag |= PARENB ;
            new_ios.c_cflag &= ~PARODD ;
            break ;
        case 'n':
        case 'N':
            new_ios.c_cflag &= ~PARENB ;
            new_ios.c_iflag &= ~INPCK ;
            break ;
        default:
            ("Wrong nEvent");
            break ;
    }

    if ( nStop == 1 )
        new_ios.c_cflag &= ~CSTOPB ;
    else if ( nStop == 2 )
        new_ios.c_cflag |= CSTOPB ;

    /*No hardware control*/

    new_ios.c_cflag &= ~CRTSCTS;

    new_ios.c_cc[VTIME] = 0 ;
    new_ios.c_cc[VMIN] = 0 ;

    /*row model*/

    new_ios.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    new_ios.c_oflag &= ~OPOST;


    tcflush(fd,TCIFLUSH) ;
    if (tcsetattr(fd,TCSANOW,&new_ios) != 0 )
    {
        perror("Set the terminal error");
        tcsetattr(fd,TCSANOW,&old_ios);

        return -1 ;
    }
    else
    {
        if(DEBUG)
            printf("Set the terminal success \n");
    }

    return 0;
}


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

    int fd ;
    int nwrite,nread;
    int length;
    char buff[10];
    unsigned char data_pan_left[7] ={0xa0,0x01,0x02,0x00,0x00,0x00,0x00};
    unsigned char data_pan_stop[7] ={0xa0,0x01,0x0f,0x00,0x00,0x00,0x00};
    unsigned char data_pan_right[7]={0xa0,0x01,0x01,0x00,0x00,0x00,0x00};
/*
    char buff[] ="0123456789";
    length = strlen(buff);
*/    
    char device_name[] = "/dev/ttyS1";
    if((fd=open_port(device_name)) < 0)
    {
        perror("Open the port error");
        exit(1);
    }

    if (set_port(fd ,19200,8,'N',1) <0 )
    {
        perror("Set the port error");
        exit(1);
    }
/*
    if( (nwrite = write(fd,buff , length )) <0 )
        printf("writh error \n");
    else
        if(DEBUG)
            printf("write %d bytes\n",nwrite);
*/
    nwrite=write(fd,data_pan_left,7);
            printf("write %d bytes\n",nwrite);
    sleep(10);
    nwrite=write(fd,data_pan_stop,7);
            printf("write %d bytes\n",nwrite);
    sleep(10);
    nwrite=write(fd,data_pan_right,7);
            printf("write %d bytes\n",nwrite);
    sleep(10);
    nwrite=write(fd,data_pan_stop,7);
            printf("write %d bytes\n",nwrite);
/*    while((nread=read(fd,buff,2)) <= 0);
            printf("read %d bytes and it is %s\n",nread,buff);
*/    
    close (fd );
    return 0 ;
}



/*Note:I write the the CSTOPB to CSTOP,so the data is error*/


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