//EM-18 RFID Module interfacing with LinkIt ONE

uint8_t count=0;        //counter for RFID card number reading
char RFID_input[12];          // character array of size 12 to store the Tag ID being presented
char tagOk[] ="1500239EA50D"; // Replace with your wanted Tag ID 


void setup() 
{
  // put your setup code here, to run once:
   Serial.begin(9600);  //For serial debugging on laptop/computer
   Serial1.begin(9600);  //RFID card is connected
}

void loop() 
{
  count=0;
  while(count<12 && Serial1.available())
  {
    RFIDRead_Check();
  }
}

void RFIDRead_Check()
{
  count = 0;
  while(Serial1.available() && count < 12)          // Read 12 characters and store them in input array
  {
    RFID_input[count++] = Serial1.read();
  }
  Serial.print(RFID_input);                             // Print RFID tag number 

  if (count==12)
  {
    Serial.println("Checking whether the RFID number read is error free or not!!");
  if((RFID_input[0] ^ RFID_input[2] ^ RFID_input[4] ^ RFID_input[6] ^ RFID_input[8] == RFID_input[10]) && (RFID_input[1] ^ RFID_input[3] ^ RFID_input[5] ^ RFID_input[7] ^ RFID_input[9] == RFID_input[11]))
  {
    Serial.println("The RFID number read is error free");
    RFID_authorize();    
  }
  else
     {
       Serial.println("error in reading RFID number");
     }
  }
}

void RFID_authorize()
{
  int compare = 1; 
  compare = (strncmp(tagOk, RFID_input,12)) ; // if both tags are equal strncmp returns a 0
  if (compare == 0)
  {
    Serial.println("The RFID number read is of authorize person");
  }
  else
  {
    Serial.println("The RFID number read is of un-authorize person");
  }
}