stm32 usart read

[787562067]

HI, ALL!
  I am new to rtems. now write the usart application by usart3 (PD8 PD9 pin)
when i input a string "qqw" by port tool Hercules,  i only get one char 'q' returned ,  so i think the read here is not
like the linux read function,  i dont know how to handle it, hope you could give some hints!




code output log:


Serial port COM2 opened
*** Simple COM1 Test ***


Opened COM1, fd=3


Hello, I'm waiting for input..
wait 5s 
*** Simple COM1 Test ***


Opened COM1, fd=3


Hello, I'm waiting for input..
wait 5s 
*** Simple COM1 Test ***


Opened COM1, fd=3


Hello, I'm waiting for input..
wait 5s 
*** Simple COM1 Test ***


Opened COM1, fd=3


Hello, I'm waiting for input..
wait 5s 
qwwq





==================================
void testCom1(void);


void testCom1(void) {
  char buffer[256] = {0};


  printf("*** Simple COM1 Test ***\n");


  //int fd = open("/dev/ttyS2", O_RDWR | O_NOCTTY | _FNDELAY);
  int fd = open("/dev/ttyS2", O_RDWR | O_NOCTTY);


  printf("\nOpened COM1, fd=%d\n\n", fd);
  if(fd < 0)
      printf("open error\n");


  #if 0
  if(fcntl(fd, F_SETFL, 0) < 0)  
  {  
    printf("fcntl failed!\n");  
    return;  
  }       
  else  
  {  
      printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));  
  }
  #endif
  fcntl(fd, F_SETFL, 0); // set blocked
  
  struct termios options;
  tcgetattr(fd, &options);


	/* setting the baud rate */
  cfsetispeed(&options, B115200);
  cfsetospeed(&options, B115200);


	
  options.c_cflag |= (CLOCAL | CREAD);


  options.c_cflag &= ~PARENB;
  options.c_cflag &= ~CSTOPB;
  options.c_cflag &= ~CSIZE;
  options.c_cflag |= CS8;


  options.c_cc[VMIN] = 0;
  options.c_cc[VTIME] = 15;


  tcsetattr(fd, TCSANOW, &options);  
      
  if(0 == isatty(fd))  
  {  
      printf("input is not a terminal device\n");  
      //return;  
  }


  int numBytes = write(fd, "Hello, I'm waiting for input..\r\n", 33);


  if (numBytes < 0) {
    printf("\nFailed to send from COM1!\n");
  }


  //wait input 
  printf("wait 5s \n");
  (void) rtems_task_wake_after( 5 * rtems_clock_get_ticks_per_second() );
  numBytes = read(fd, buffer, 20);
  printf("read bytes %d\n", numBytes);
  strerror(errno);
  if (numBytes < 0) {
    printf("\nFailed to read from COM1!\n");


  }
  else if(numBytes == 0)
  {
    printf("read error return 0\n");
  }
  else
  {
    //buffer[numBytes] = 0; // terminate
    printf("rev: %s\n", buffer);
  }


  close(fd);
}
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