MFRC522.ino

/*
 * --------------------------------------------------------------------------------------------------------------------
 * Example sketch/program showing how to read data from a PICC to serial.
 * --------------------------------------------------------------------------------------------------------------------
 * This is a MFRC522 library example; for further details and other examples see: https://github.com/miguelbalboa/rfid
 * 
 * Example sketch/program showing how to read data from a PICC (that is: a RFID Tag or Card) using a MFRC522 based RFID
 * Reader on the Arduino SPI interface.
 * 
 * When the Arduino and the MFRC522 module are connected (see the pin layout below), load this sketch into Arduino IDE
 * then verify/compile and upload it. To see the output: use Tools, Serial Monitor of the IDE (hit Ctrl+Shft+M). When
 * you present a PICC (that is: a RFID Tag or Card) at reading distance of the MFRC522 Reader/PCD, the serial output
 * will show the ID/UID, type and any data blocks it can read. Note: you may see "Timeout in communication" messages
 * when removing the PICC from reading distance too early.
 * 
 * If your reader supports it, this sketch/program will read all the PICCs presented (that is: multiple tag reading).
 * So if you stack two or more PICCs on top of each other and present them to the reader, it will first output all
 * details of the first and then the next PICC. Note that this may take some time as all data blocks are dumped, so
 * keep the PICCs at reading distance until complete.
 * 
 * @license Released into the public domain.
 * 
 * Typical pin layout used:
 * -----------------------------------------------------------------------------------------
 *             MFRC522      Arduino       Arduino   Arduino    Arduino          Arduino
 *             Reader/PCD   Uno/101       Mega      Nano v3    Leonardo/Micro   Pro Micro
 * Signal      Pin          Pin           Pin       Pin        Pin              Pin
 * -----------------------------------------------------------------------------------------
 * RST/Reset   RST          9             5         D9         RESET/ICSP-5     RST
 * SPI SS      SDA(SS)      10            53        D10        10               10
 * SPI MOSI    MOSI         11 / ICSP-4   51        D11        ICSP-4           16
 * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
 * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
 */

#include <SPI.h>
#include <MFRC522.h>
#include <Keyboard.h>

constexpr uint8_t RST_PIN = 9;  // Configurable, see typical pin layout above
constexpr uint8_t SS_PIN = 10;  // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN);  // Create MFRC522 instance

int RXLED = 17;

void setup() {
  pinMode(RXLED, OUTPUT); 
  Serial.begin(9600);
  //while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
  SPI.begin();      // Init SPI bus
  mfrc522.PCD_Init();   // Init MFRC522
  mfrc522.PCD_DumpVersionToSerial();  // Show details of PCD - MFRC522 Card Reader details
  Keyboard.begin();
}

void readHex(byte *buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
    Serial.print(buffer[i], HEX);
  }
}

void loop() {
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    digitalWrite(RXLED, HIGH); 
    return;
  }

    // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    return;
  }
  
  digitalWrite(RXLED, LOW);
  Serial.print("RFID UID: ");
  readHex(mfrc522.uid.uidByte, mfrc522.uid.size);
  Serial.println();


  // SET YOUR UID HERE (you should see it in your serial monitor)
  if (mfrc522.uid.uidByte[0] == 0x00 && 
      mfrc522.uid.uidByte[1] == 0x00 &&
      mfrc522.uid.uidByte[2] == 0x00 &&
      mfrc522.uid.uidByte[3] == 0x00) {
      Serial.println("Correct UID");
  }
  else {
    Serial.println("Incorrect UID");
    delay(5000);
    return;
  }

  digitalWrite(RXLED, HIGH);

  Serial.println("Printing password...");
  Keyboard.print("<your secret password>");
  delay(1000);
  Keyboard.write(10);
  
  delay(5000);                                          
}