Linux串口编程-3-even校验

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

main()
{
    int fd;
    int i;
    int len;
    int n = 0;
    char b[1]={0x01};
    char read_buf[256];
    char write_buf[256];
    struct termios opt;

    fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY);    //默认为阻塞读方式
    if(fd == -1)
    {
        perror("open serial 0\n");
        exit(0);
    }

    tcgetattr(fd, &opt);
    cfsetispeed(&opt, B9600);
    cfsetospeed(&opt, B9600);

    if(tcsetattr(fd, TCSANOW, &opt) != 0 )
    {
       perror("tcsetattr error");
       return -1;
    }
    opt.c_cflag &= ~CSIZE;
    opt.c_cflag |= CS8;
    opt.c_cflag &= ~CSTOPB;
    opt.c_cflag &= ~PARENB;
    opt.c_cflag &= ~INPCK;
    opt.c_cflag |= (CLOCAL | CREAD);

    opt.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);

    opt.c_oflag &= ~OPOST;
    opt.c_oflag &= ~(ONLCR | OCRNL);    //添加的

    opt.c_iflag &= ~(ICRNL | INLCR);
    opt.c_iflag &= ~(IXON | IXOFF | IXANY);    //添加的
    //=======================================
    //EVEN
    opt.c_cflag |=  PARENB | CS8;
    opt.c_iflag &= ~PARODD;
    //=======================================
//    //=====================================
//    //space
//    opt.c_cflag |=  PARENB | CS8 | 0X40000000 | PARODD;
//    //=====================================
//    //=====================================
//    //mark
//    opt.c_cflag |= PARENB | CS8 | CMSPAR ;
//    opt.c_cflag &= PARODD;
//    //=====================================

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

    tcflush(fd, TCIOFLUSH);

    printf("configure complete\n");

    if(tcsetattr(fd, TCSANOW, &opt) != 0)
    {
        perror("serial error");
        return -1;
    }
    printf("start send and receive data\n");

    while(1)
    {

        n = 0;
        len = 0;
        printf("hw\n");
        bzero(read_buf, sizeof(read_buf));    //类似于memset
        bzero(write_buf, sizeof(write_buf));
        write(fd,b,sizeof b);
        usleep(50000);
    }
}