RFID Reader - ttyS0

Refererence, 1. Serial Programming Guide for POSIX Operating Systems 2. Serial Programming HOWTO (Translated) 3. Summit RFID Reader 4. QextSerialPort ... a Qt Serial Class Programmed as below,

#include <stdio.h>   /* Standard input/output definitions */
#include <string.h>  /* String function definitions */
#include <unistd.h>  /* UNIX standard function definitions */
#include <fcntl.h>   /* File control definitions */
#include <errno.h>   /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */


char DEV_RFID[16]="/dev/ttyS0";


int main(int argc, char **argv)
{

  struct timeval timeout;
      timeout.tv_sec  = 0;
      timeout.tv_usec = 500;

  // ttyS1 can be chosed if ttyS0 is in used
  if(argc>1)
      strcpy(DEV_RFID, "/dev/ttyS1");

  fprintf(stdout, "[RFID] ----------- DEMO -------------------\n");
  fprintf(stdout, "[RFID] Connecting to %s\n", DEV_RFID);

  // Open a Serial Port
  int fd;
  fd = open(DEV_RFID, O_RDWR | O_NOCTTY);
  if (fd < 0) {
      perror(DEV_RFID);
      exit(1);
  }
  fprintf(stdout, "[RFID] %s is connected\n", DEV_RFID);

  struct termios oldtio, newtio;

  // Gets the current serial port settings.
  tcgetattr(fd, &oldtio);
  bzero(&newtio, sizeof(newtio));

  // Termios Structure Members --------------------------------------
  // Control options, 19200 baud/8 data bits/Enable receiver/Local line
      newtio.c_cflag |= (B19200|CS8|CREAD|CLOCAL);
      newtio.c_lflag &= (~(ICANON|ECHO|ECHOE|ECHOK|ECHONL|ISIG));
  // Input options
      newtio.c_iflag &= (~(INPCK|IGNPAR|PARMRK|ISTRIP|ICRNL|IXANY));
  // Output options
      newtio.c_oflag &= (~OPOST);
  // Control characters
      newtio.c_cc[VMIN]  = 0;
  newtio.c_cc[VTIME] = 5;

  // no flow control
  newtio.c_cflag&=(~CRTSCTS);
  newtio.c_iflag&=(~(IXON|IXOFF|IXANY));

  // Flushes the input and/or output queue.
  tcflush(fd, TCIFLUSH);
  // Make changes now without waiting for data to complete
  tcsetattr(fd, TCSANOW, &newtio);

  // Variables for Read/Write
  char cmd[3] = { 0x1B, 'I', 0x0D };
  unsigned char buf[256]={0} ;
  char id[32]={0}, chs[2]={0};
  int  i=0, res;

  while(1) {
      bzero(id, sizeof(id));
      fprintf(stdout, "[RFID] Reading ...\n");  
      // Send Request to RFID Reader
      write(fd, cmd, 3);
      // Read Response from RFID Reader
      res = read(fd, buf, 16);
      // Print the Response in Hex
      if(res > 0) {   
              // Convert Response into Hex Format
          // For checking the Respones String 
          for(i=0; i<res; i++) {  
             sprintf(chs, "%02X", buf[i]);     
                strcat(id, chs );
          }
          fprintf(stdout, "[RFID] Card ID: ");
          fprintf(stdout, " %s\n", id);
      }      
            sleep(3);  
  }  

  // Close DEV_RFID used.
  close(fd);
  fprintf(stdout, "\n[RFID] Closed\n");

  // Restore old terminal settings
  tcsetattr(fd, TCSANOW, &oldtio);
  fprintf(stdout, "[RFID] ---------- End of Program ----------\n");
  return 0;
}

$ ./myRFIDreader 1 [RFID] ----------- DEMO ------------------- [RFID] Connecting to /dev/ttyS1 [RFID] /dev/ttyS1 is connected [RFID] Reading ... [RFID] Card ID: 1B054661696C21 (Nothing read return value) [RFID] Reading ... [RFID] Card ID: 1B054661696C21 [RFID] Reading ... [RFID] Card ID: 1B0E0F3871C1CD0A (Part of Card 1) [RFID] Reading ... [RFID] Card ID: 8007E000003F038B (Part of Card 1) [RFID] Reading ... [RFID] Card ID: 1B0E0F3058C1CD0A8007E000003F038B (Card 1 No.) [RFID] Reading ... [RFID] Card ID: 1B054661696C21 [RFID] Reading ... [RFID] Card ID: 1B054661696C21 [RFID] Reading ... [RFID] Card ID: 1B0E0F3871C1CD0A8007E000003F038B (Card 2 No.) [RFID] Reading ... [RFID] Card ID: 1B054661696C21 [RFID] Reading ... [RFID] Card ID: 1B054661696C21 .