【嵌入式开发技术之串口】Linux下串口主机程序

作者：gnuhpc 
出处：http://www.cnblogs.com/gnuhpc/

#include     <stdio.h>      /*标准输入输出定义*/
#include     <stdlib.h>     /*标准函数库定义*/
#include     <unistd.h>     /*Unix标准函数定义*/
#include     <sys/types.h>  /**/
#include     <sys/stat.h>   /**/
#include     <fcntl.h>      /*文件控制定义*/
#include     <termios.h>    /*PPSIX终端控制定义*/
#include     <errno.h>      /*错误号定义*/

/***@brief  设置串口通信速率
*@param  fd     类型 int  打开串口的文件句柄
*@param  speed  类型 int  串口速度
*@return  void*/

int speed_arr[] = { B38400, B19200, B9600, B4800, B2400, B1200, B300,
        B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {38400,  19200,  9600,  4800,  2400,  1200,  300,
        38400,  19200,  9600, 4800, 2400, 1200,  300, };
void set_speed(int fd, int speed)
{
  int   i;
  int   status;
  struct termios   Opt;
  tcgetattr(fd, &Opt);
  for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++)
   {
       if  (speed == name_arr[i])
       {
           tcflush(fd, TCIOFLUSH);
        cfsetispeed(&Opt, speed_arr[i]);
        cfsetospeed(&Opt, speed_arr[i]);
        status = tcsetattr(fd, TCSANOW, &Opt);
        if  (status != 0)
            perror("tcsetattr fd1");
         return;
         }
   tcflush(fd,TCIOFLUSH);
   }
}
/**
*@brief   设置串口数据位，停止位和效验位
*@param  fd     类型  int  打开的串口文件句柄*
*@param  databits 类型  int 数据位   取值 为 7 或者8*
*@param  stopbits 类型  int 停止位   取值为 1 或者2*
*@param  parity  类型  int  效验类型 取值为N,E,O,,S
*/
int set_Parity(int fd,int databits,int stopbits,int parity)
{
    struct termios options;
 if  ( tcgetattr( fd,&options)  !=  0)
  {
      perror("SetupSerial 1");
      return(FALSE);
  }
  options.c_cflag &= ~CSIZE;
  switch (databits) /*设置数据位数*/
  {
      case 7:
          options.c_cflag |= CS7;
          break;
      case 8:
        options.c_cflag |= CS8;
        break;
    default:
        fprintf(stderr,"Unsupported data size/n");
        return (FALSE);
    }
  switch (parity)
      {
      case 'n':
    case 'N':
        options.c_cflag &= ~PARENB;   /* Clear parity enable */
        options.c_iflag &= ~INPCK;     /* Enable parity checking */
        break;
    case 'o':
    case 'O':
        options.c_cflag |= (PARODD | PARENB);  /* 设置为奇效验*/ 
        options.c_iflag |= INPCK;             /* Disnable parity checking */
        break;
    case 'e':
    case 'E':
        options.c_cflag |= PARENB;     /* Enable parity */
        options.c_cflag &= ~PARODD;   /* 转换为偶效验*/  
        options.c_iflag |= INPCK;       /* Disnable parity checking */
        break;
    case 'S':
    case 's':  /*as no parity*/
        options.c_cflag &= ~PARENB;
        options.c_cflag &= ~CSTOPB;
        break;
    default:
        fprintf(stderr,"Unsupported parity/n");
        return (FALSE);
        }
  /* 设置停止位*/   
  switch (stopbits)
      {
      case 1:
          options.c_cflag &= ~CSTOPB;
        break;
    case 2:
        options.c_cflag |= CSTOPB;
        break;
    default:
        fprintf(stderr,"Unsupported stop bits/n");
        return (FALSE);
    }
  /* Set input parity option */
  if (parity != 'n')
          options.c_iflag |= INPCK;
    options.c_cc[VTIME] = 150; // 15 seconds
    options.c_cc[VMIN] = 0;

  tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */
  if (tcsetattr(fd,TCSANOW,&options) != 0)
      {
          perror("SetupSerial 3");
        return (FALSE);
    }
  return (TRUE);
 }
/**
*@breif 打开串口
*/
int OpenDev(char *Dev)
{
int    fd = open( Dev, O_RDWR );         //| O_NOCTTY | O_NDELAY
    if (-1 == fd)
        { /*设置数据位数*/
            perror("Can't Open Serial Port");
            return -1;
        }
    else
    return fd;

}
/**
*@breif     main()
*/
int main(int argc, char **argv)
{
    int fd;
    int nread;
    char buff[512];
    char *dev ="/dev/ttyS1";
    fd = OpenDev(dev);
    if (fd>0)
    set_speed(fd,19200);
    else
        {
        printf("Can't Open Serial Port!/n");
        exit(0);
        }
  if (set_Parity(fd,8,1,'N')== FALSE)
  {
    printf("Set Parity Error/n");
    exit(1);
  }
  while(1)
      {
           while((nread = read(fd,buff,512))>0)
           {
              printf("/nLen %d/n",nread);
              buff[nread+1]='/0';
              printf("/n%s",buff);
            }
      }
    //close(fd);
    //exit(0);
}