Linux下读写UART串口的代码，从IBM Developer network上拿来的东西，操作比較的复杂，就直接跳过了，好在代码能用，记录一下～

两个实用的函数～

/**
*@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[] = {B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300,B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {115200, 38400, 19200, 9600, 4800, 2400, 1200,  300, 115200, 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; tcflush(fd,TCIFLUSH);options.c_cc[VTIME] = 150; /* 设置超时15 seconds*/   options.c_cc[VMIN] = 0; /* Update the options and do it NOW */if (tcsetattr(fd,TCSANOW,&options) != 0)   { perror("SetupSerial 3");   return (FALSE);  } options.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  /*Input*/options.c_oflag  &= ~OPOST;   /*Output*/return (TRUE);
}

调用的方法比較的简单，例如以下。fd是打开的tty设备的文件句柄

    set_speed(fd,115200);if (set_Parity(fd,8,1,'N') == FALSE)  {printf("Set Parity Error\n");}

总的測试代码例如以下。

#include <sys/types.h>#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#define BAUDRATE        B115200
#define UART_DEVICE     "/dev/ttyS3"#define FALSE  -1
#define TRUE   0/**
*@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[] = {B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300,B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {115200, 38400, 19200, 9600, 4800, 2400, 1200,  300, 115200, 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; tcflush(fd,TCIFLUSH);options.c_cc[VTIME] = 150; /* 设置超时15 seconds*/   options.c_cc[VMIN] = 0; /* Update the options and do it NOW */if (tcsetattr(fd,TCSANOW,&options) != 0)   { perror("SetupSerial 3");   return (FALSE);  } options.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  /*Input*/options.c_oflag  &= ~OPOST;   /*Output*/return (TRUE);
}int main(int argc, char *argv[])
{int    fd, c=0, res;char  buf[256];printf("Start...\n");fd = open(UART_DEVICE, O_RDWR);if (fd < 0) {perror(UART_DEVICE);exit(1);}printf("Open...\n");set_speed(fd,115200);if (set_Parity(fd,8,1,'N') == FALSE)  {printf("Set Parity Error\n");exit (0);}printf("Reading...\n");while(1) {res = read(fd, buf, 255);if(res==0)continue;buf[res]=0;printf("%s", buf);if (buf[0] == 0x0d)printf("\n");if (buf[0] == '@') break;}printf("Close...\n");close(fd);return 0;
}