Linux串口编程（中断方式和select方式）

struct termios
{

tcflag_t c_iflag;
/* 输入选项标志 */

tcflag_t c_oflag;
/* 输出选项标志 */

tcflag_t c_cflag;
/* 控制选项标志 */

tcflag_t c_lflag;
/* 本地选项标志 */

unsigned char c_line /*线控制*/

cc_t c_cc[NCCS];
/* 控制特性 */
};

需要包括的头文件是：
#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>
#include
"Set_Uart.c"

int main(void)
{

  int fd;

  int nwrite,i;

  char buff[]
= "Hello world!\n";

  fd = 0;

  /*打开串口*/

  if((fd
= open_port(fd,0))
< 0)
//在我的Set_Uart.c文件中定义。

  {

    perror("open_port error!\n");

    return (-1);

  }

  /*设置串口*/

  if((i
= set_opt(fd,115200,8,'N',1))
< 0)
//在Set_Uart.c文件中定义

  {

    perror("set_opt error!\n");

    return (-1);

  }

  printf("fd =%d\n",fd);

  /*向串口写入字符串*/
sleep(10);  

  nwrite = write(fd,buff,strlen(buff));
sleep(10);

  printf("nwrite = %d\n",nwrite);

  close(fd);

  return (1);
}

int main(void)
{

  int fd,res,i;

  struct sigaction saio;
/*definition of signal axtion */

  char buf[255];

  fd_set rd;

  fd = 0;

  /*打开串口*/

  if((fd
= open_port(fd,1))<0)

  {

    perror("open_port error!\n");

    return (-1);

  }

  /* install the signal handle before making the device asynchronous*/

  saio.sa_handler
= signal_handler_IO;

  sigemptyset(&saio.sa_mask);

  //saio.sa_mask = 0; 必须用sigemptyset函数初始话act结构的sa_mask成员

  saio.sa_flags = 0;

  saio.sa_restorer
= NULL;

  sigaction(SIGIO,&saio,NULL);

  /* allow the process to recevie SIGIO*/

  fcntl(fd,F_SETOWN,getpid());

  /* Make the file descriptor asynchronous*/

  fcntl(fd,F_SETFL,FASYNC);

  

  /*设置串口*/

  if((i= set_opt(fd,115200,8,'N',1))<0)

  {

    perror("set_opt error!\n");

    return (-1);

  }

  /* loop while waiting for input,normally we would do something useful here*/

  while(STOP
==
FALSE)

  {

    usleep(100000);

    /* after receving SIGIO ,wait_flag = FALSE,input is availabe and can be read*/

    if(wait_flag
==
FALSE)

    {

          memset(buf,0,255);

      res = read(fd,buf,255);

       printf("nread=%d,%s\n",res,buf);

      if(res
== 1)

        STOP = TRUE;
/*stop loop if only a CR was input */

       wait_flag =
TRUE; /*wait for new input*/

    }

  }

  close(fd);

  return 0; 
}
/******************************************

 信号处理函数，设备wait_flag=FASLE

 ******************************************************/
void signal_handler_IO(int status)
{

   printf("received SIGIO signale.\n");

  wait_flag = FALSE; 
}

int main(void)
{

  int fd;

  int nread,nwrite,i;

  char buff[8];

  fd_set rd;

  fd = 0;

  /*打开串口*/

  if((fd
= open_port(fd,1))
< 0)

  {

    perror("open_port error!\n");

    return ;

  }

  /*设置串口*/

  if((i= set_opt(fd,115200,8,'N',1))
< 0)

  {

    perror("set_opt error!\n");

    return (-1);

  }

  /*利用select函数来实现多个串口的读写*/
while(1)
{

  FD_ZERO(&rd);

  FD_SET(fd,&rd);

  while(FD_ISSET(fd,&rd))

  {

    if(select(fd+1,&rd,NULL,NULL,NULL)
< 0)

      perror("select error!\n");

    else

    {

      while((nread
= read(fd,buff,8))>0)

      {

        printf("nread = %d,%s\n",nread,buff);

     printf("nread = %d,%s\n",nread,buff);

      }

    }

  }
}
close(fd);

    return ;
}

./Read_Uart_IRQ

fcntl = 0

isatty success !

fd-open=3
set

received SIGIO signale.

nread=13,Hello