RFID RC522 Authentication failed while writing tag

Projects Programming
1

Hello Community,

I am reaching out seeking assistance with a challenge I am encountering while attempting to write data onto an RFID tag using NodeMCU8266. Despite multiple attempts, I consistently encounter an "Authentication failed!" error message.

Below, I've provided the code I'm currently using:

#include <ESP8266WiFi.h>
#include <SPI.h>
#include <MFRC522.h>

#define WIFI_SSID "DIGITALUX"
#define WIFI_PASSWORD "OfficeNet22"

#define RST_PIN D3
#define SS_PIN D8

MFRC522 mfrc522(SS_PIN, RST_PIN);


/*///////////////////////////////////////////////////////////////////////////////////////////////////
                                      Write Function!
///////////////////////////////////////////////////////////////////////////////////////////////////*/

void writeData(byte* buffer, byte block, const char* prompt) {
  Serial.println(prompt);
  byte len = Serial.readBytesUntil('#', (char *)buffer, 16);
  for (byte i = len; i < 16; i++) buffer[i] = ' ';

  MFRC522::MIFARE_Key key;
  for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;
  
  if (mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, block, &key, &(mfrc522.uid)) == MFRC522::STATUS_OK) {
    if (mfrc522.MIFARE_Write(block, buffer, 16) == MFRC522::STATUS_OK) {
      Serial.println("Data written successfully");
    } else {
      Serial.println("Failed to write data");
    }
  } else {
    Serial.println("Authentication failed");
  }
}

/*///////////////////////////////////////////////////////////////////////////////////////////////////
                                      setup Function!
///////////////////////////////////////////////////////////////////////////////////////////////////*/

void setup() {
  Serial.begin(115200);
  SPI.begin();
  mfrc522.PCD_Init();

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.println("Connecting");
  while (!WiFi.isConnected()) {
    Serial.print(".");
    delay(50);
  }
  Serial.println();
  delay(500);
  Serial.print("Connected with IP : ");
  Serial.println(WiFi.localIP());
}

/*///////////////////////////////////////////////////////////////////////////////////////////////////
                                      Loop Function!
///////////////////////////////////////////////////////////////////////////////////////////////////*/

void loop() {
  if (!mfrc522.PICC_IsNewCardPresent()) {
    return;
  }
  if (!mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  Serial.print(F("Card UID:"));
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println();

  byte buffer[18];
  byte block;
  MFRC522::StatusCode status;
  Serial.setTimeout(20000L);

  // Write user data to RFID card
  writeData(buffer, 1, "Enter Your Name: ");

  mfrc522.PICC_HaltA();
  mfrc522.PCD_StopCrypto1();
}

Here is the output I got every time.

1234

I've tried different cards, but every time I get the same error. I'm not sure if there is a problem in my code because I've carefully checked all my hardware connections multiple times.

Thank you very much in advance for your time and assistance.

Best regards,
Ali

2

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