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* --------------------------------------------------------------------------------------------------------------------
* 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:
* 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
* -----------------------------------------------------------------------------------------
* 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() {
//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
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);
// Select one of the cards
if ( ! mfrc522.PICC_ReadCardSerial()) {
digitalWrite(RXLED, LOW);
Serial.print("RFID UID: ");
readHex(mfrc522.uid.uidByte, mfrc522.uid.size);
// 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");
digitalWrite(RXLED, HIGH);
Serial.println("Printing password...");
Keyboard.print("<your secret password>");
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