int card = 0;       //
int rfidstate = 0;
int cardtimer = 0;

void setup() {
  Serial.begin(9600); // Initialize serial monitor
  pinMode(A1,INPUT);  // Connect FAST RFID reader data line to A1 input.  Set A1 to digital input
  Serial.println("FAST RFID READER");  // Write this to the serial monitor

}

void loop()  // The main loop simply acts to call the cardread() function over and over 
{   
cardread();
}



void cardread()  // This function acts to read cards, and to write card data to the serial monitor.  So power up your arduino, load this code, and open the serial monitor.
{
  card = 0;      // Set int card to 0.
  rfidstate = 0; // Set rfid state to 0
  while(digitalRead(A1) == LOW){  // Wait until card data on A1 line goes from 0v to 5v.  Once there, this while loop will end.
    {}
  }
  while(rfidstate == 0){  // This new while loop will execute until rfidstate is more than 0
    {
  while(digitalRead(A1) == HIGH){    // This new while loop will wait until the A1 line goes back to 0v from 1v.
    {}
  }
  card = card + 1;                   // Add 1 to card integer
  cardtimer = 0;                     // cardtimer integer set to 0;
  while(digitalRead(A1) == LOW){     // This while loop is a timer.  It waits for A1 to go from 0v to 5v again.  It counts pulses from the FAST rfid reader.
    {
      delay(1);                      // Wait 1ms
      cardtimer = cardtimer + 1;     // Add 1 to cardtimer integer
      if(cardtimer > 7)              // If cardtimer value is higher than 7 (7 ms has elapsed), then to do the following
      {
        if(card < 6)                 // If card value (Amount of incoming pulses) is less than 6
        {
        Serial.print("Card#");       // Then write "Card#" to the serial monitor
        Serial.print(card);          // Write card value
        Serial.println(" Detected!"); // Write "detected"
        rfidstate = 1;                // rfidstate is changed to 1, which means that this function will end
        break;                        // Leave this while loop
        }
        else                          // If card is higher than 5, then do the following
        {
        Serial.println("Incorrect Card Detected!");  // Write to serial monitor "Incorrect Card Detected!'
        rfidstate = 1;                               // rfidstate is changed to 1, which means that this function will end
        break;                                       // leave this while loop
        }
      }
    }
    }
    }
  }
}