串口与select（超时）

串口测试程序，将串口的2，3脚直接相连，实现同一台电脑的收发信息。

设置串口函数

int speed_array[]={B115200,B38400,B19200,B9600,B4800,B2400,B1200,B300};
int name_array[]={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 {
  if(speed==name_array[i])
  {    
   tcflush(fd,TCIOFLUSH);    
   cfsetispeed(&Opt,speed_array[i]); 
   cfsetospeed(&Opt,speed_array[i]);  
   status=tcsetattr(fd,TCSANOW,&Opt); 
   if(status!=0)
   {       
    perror("tcsetattr fd1"); 
    exit(0);    
   }   
   tcflush(fd,TCIOFLUSH);  
  } 
 }
}
                     
int set_Parity(int fd,int databits,int stopbits,int parity)
{
   struct termios options;
   if(tcgetattr(fd,&options)!= 0)
    {
      perror ("SetupSerial 1");
      return -1;
    }
   options.c_cflag&= ~CSIZE;
   switch(databits)
    {
     case 7:
      options.c_cflag|=CS7;
      break;
   case 8:
      options.c_cflag|=CS8;
      break;
   default:
      fprintf(stderr,"Unsupported data size\n");
      return -1;
    }
   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);
       options.c_iflag|=INPCK; /* Disnable parity checking */
      break;
   
   case 'e':
     case 'E':
       options.c_cflag|=PARENB; /* Enable parity */
       options.c_cflag&=~PARODD;
       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 -1;
    }

   switch(stopbits)
    {
     case 1:
       options.c_cflag&= ~CSTOPB;
      break;

     case 2:
       options.c_cflag|=CSTOPB;
      break;

     default:
       fprintf(stderr,"Unsupported stop bits\n");
      return -1;
    }
  /* Set input parity option */
   if(parity!='n')
     options.c_iflag|=INPCK;

   tcflush(fd,TCIFLUSH);
   options.c_cc[VTIME]=50;
   options.c_cc[VMIN]=0;      /* Update the options and do it NOW */

   options.c_lflag&=~(ICANON|ECHO|ECHOE|ISIG);
   options.c_iflag&=~(ICRNL|IXON);
   options.c_oflag&=~(ICRNL|IXON);

   options.c_oflag&=~OPOST;

   if(tcsetattr(fd,TCSANOW,&options)!= 0)
    {
      perror("SetupSerial 3");
      return -1;
    }
   return 0;
}

send.c

#include      
#include     
#include     
#include  
#include   
#include
#include
#include

int main()
{
 int fd;
  fd=open("/dev/ttyS1",O_RDWR);        
 if(fd==-1) 
 {    
  perror("Can't Open Serial Port\n");
  exit(-1); 
 } 
 set_speed(fd,115200);
  if(set_Parity(fd,8,1,'n')==-1)
  {
    printf("set_parity error\n");
  }
  char buf[]="hello";
  write(fd,buf,sizeof(buf));

  close(fd);
}

 

recive.c

#include      
#include     
#include     
#include  
#include   
#include
#include
#include
#include

int main()
{ 
 int fd;
  fd=open("/dev/ttyS1",O_RDWR|O_NONBLOCK);        
 if(fd==-1) 
 {    
  perror("Can't Open Serial Port\n");
  exit(-1); 
 } 
 set_speed(fd,115200);
   if(set_Parity(fd,8,1,'n')==-1)
   {
      printf("set_parity error\n");
   }
 fd_set fds;
        struct timeval timeout={10,0};
   char buf[100];
   char *p;
   p=buf;
 FD_ZERO(&fds);
 FD_SET(fd,&fds);
 switch(select(fd+1,&fds,NULL,NULL,&timeout))
 {
  case -1:printf("error\n");return 0;
  case 0:printf("timeout\n");break;
  default:
  if(FD_ISSET(fd,&fds))
  {
   read(fd,p,1);
   while(*p)
     {
      printf("%c",*p);
      p++;
      read(fd,p,1); 
     }
   printf("\n");
  }
 }

close(fd);
}