Linux下串口编程

    最近你才开始接触Linux下的编程，实验室接手了一个小的串口协议的编写，主要是一个握手协议和相关功能的设置：很简单，还没有继续完善。就是一个简单程序而已，以后可能还要修改，不过先在这里记录下来吧！

   经过这次编程，串口编程基本上是掌握了，接下来继续向Linux下的编程开进！

#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>

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;
    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] = 1;
    tcflush(fd,TCIFLUSH);
    if((tcsetattr(fd,TCSANOW,&newtio))!=0)
    {
        perror("com set error");
        return -1;
    }
    printf("set done!\n");
    return 0;
}

int open_port(int fd,int comport)
{
    char *dev[]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2"};
    long vdisable;
    if (comport==1)
    {
        fd = open( "/dev/ttyS0", O_RDWR);
        if (-1 == fd)
        {
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
        printf("open ttyS0 .....\n");
    }
    else if(comport==2)
    {
        fd = open( "/dev/ttyS1", O_RDWR);
        if (-1 == fd)
        {
        perror("Can't Open Serial Port");
        return(-1);
        }
        else
        printf("open ttyS1 .....\n");
    }
    else if (comport==3)
    {
    fd = open( "/dev/ttyS2", O_RDWR);
    if (-1 == fd){
        perror("Can't Open Serial Port");
        return(-1);
    }
    else
        printf("open ttyS2 .....\n");
    }
      if(fcntl(fd, F_SETFL, 0)<0)
        printf("fcntl failed!\n");
    else
        printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));
    if(isatty(STDIN_FILENO)==0)
        printf("standard input is not a terminal device\n");
    else
        printf("isatty success!\n");
    printf("fd open=%d\n",fd);
    return fd;
}
float data_sovle(char buff[])
{
    float a,b,c;
    if (buff[0]/32%2==0)
    {
        a=((float)(buff[0]/32%2*256+buff[1]))/10.0;
    }
    else
    {
        a=-((float)(buff[0]/32%2*256+buff[1]))/10.0;
    }
    printf("Current W %2.2f/s\n",a);
    if (buff[0]/128%2==0)
    {
        b=(float)buff[2]/100;
    }
    else
    {
        b=-(float)(buff[2])/100;
    }
    printf("Current Vx %2.2fm/s\n",b);
    if (buff[0]/64%2==0)
    {
        c=(float)buff[3]/100;
    }
    else
    {
        c=-(float)(buff[3])/100;
    }
    printf("Current Vy %2.2fm/s\n",c);
    return 0;
}
int main(void)
{
    int fd;
    int nread_hand,nwrite_hand,nread,nwrite,i;
    char buff_hand[1];
    char buff_handsend[1]={21};
    char buff_recv_data4[4];
    char buff_recv_data5[5];
    char buff_send_data1[5]={24,0,182,100,31};
    char buff_send_data2[5]={1,144,0,0,31};
    char buff_send_data3[5]={137,44,194,80,41};
    char buff_signal[1];
    char buff_switch[1];
    char buff_temp[1];
    if((fd=open_port(fd,1))<0)
    {
        perror("open_port error");
        return;
    }
    if((i=set_opt(fd,115200,8,'O',1))<0)
    {
        perror("set_opt error");
        return;
    }
    printf("fd=%d\n",fd);
    sleep(3);

    nread_hand=read(fd,buff_hand,1);
/*    printf("buff_hand is %d %d\n",nread_hand,buff_hand[0]);
    nwrite=write(fd,buff_handsend,1);
    printf("222-%d",buff_handsend[0]);*/
    if(buff_hand[0]==21)
    {
        printf("buf_hand1 %d\n",buff_hand[0]);
        nwrite_hand=write(fd,buff_handsend,1);
        printf("buf_hand2 %d\n",buff_handsend[0]);
    }
    else
    {
        printf("receive hand error\n");
        return  0;
    }

    nread=read(fd,buff_recv_data4,4);
    data_sovle(buff_recv_data4);
    printf("Input the control mode");
    scanf("%d",buff_signal);
    buff_switch[0]=buff_signal[0];
    while(1)
    {

        switch(buff_switch[0])
        {
            case 31:
            {
                printf("Please input control mode ");
                scanf("%d",buff_temp);
                printf("%d",buff_temp[0]);
                switch(buff_temp[0])
                {
                    case 1:
                        nwrite=write(fd,buff_send_data1,5);
                        nread=read(fd,buff_recv_data5,5);
                        data_sovle(buff_recv_data5);
                        buff_switch[0]=buff_send_data1[4];
                        break;
                    case 2:
                        nwrite=write(fd,buff_send_data2,5);
                        nread=read(fd,buff_recv_data5,5);
                        data_sovle(buff_recv_data5);
                        buff_switch[0]=buff_send_data2[4];
                        break;
                    case 3:
                        nwrite=write(fd,buff_send_data3,5);
                        nread=read(fd,buff_recv_data5,5);
                        data_sovle(buff_recv_data5);
                        buff_switch[0]=buff_send_data3[4];
                        break;
                }

            }
            break;
            case 41:
                nread=read(fd,buff_recv_data4,4);
                data_sovle(buff_recv_data4);
                printf("Please input replay signal ");
                scanf("%d",buff_signal);
                buff_switch[0]=buff_signal[0];
                break;
            case 51:
                nread=read(fd,buff_recv_data4,4);
                data_sovle(buff_recv_data4);
                printf("Please input replay signal ");
                scanf("%d",buff_signal);
                buff_switch[0]=buff_signal[0];
                break;
            default:
                nread=read(fd,buff_recv_data4,4);
                data_sovle(buff_recv_data4);
                printf("Please input replay signal ");
                scanf("%d",buff_signal);
                buff_switch[0]=buff_signal[0];
                break;
        }
    }

    close(fd);
    return 0;

}

   还会继续修改，这个程序也是参考别人的修改的，加上了一些附加功能，还有中间编程还有部队的地方，一些细节还要继续修改！

   第一次记录自己的Linux学习经历，有什么不好的地方还请大家指正，帮助我进步！编程还真是一个技术活啊，吹牛真是不行的，实践了才知道啊！当然感觉不错，也许这就是开源分享。