Arduino Driven PN532 Module reading MIFARE Ultralight

#include <Wire.h>
#include "PN532_I2C.h"
#include "PN532.h"

PN532_I2C m1kreader(Wire);
PN532 nfc(m1kreader);

void setup() {
  // Debug msg
  Serial.begin(115200);
  // Serial1.begin(115200);  // send to touchboard

  // Start the TWI
  nfc.begin();
  // Debug purpose (Block program for output)
  while (!Serial);
  uint32_t versiondata = nfc.getFirmwareVersion();
  if (! versiondata) {
    Serial.print("Didn't find PN53x board");
    while (1); // halt
  }
  // Got ok data, print it out!
  Serial.print("Found chip PN5"); Serial.println((versiondata >> 24) & 0xFF, HEX);
  Serial.print("Firmware ver. "); Serial.print((versiondata >> 16) & 0xFF, DEC);
  Serial.print('.'); Serial.println((versiondata >> 8) & 0xFF, DEC);

  nfc.SAMConfig();

  Serial.println("Waiting for an ISO14443A Card ...");
}

void loop() {
  uint8_t success;
  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
  uint8_t uidLength;                        // Length of the UID (4 or 7 bytes depending on ISO14443A card type)

  // Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
  // 'uid' will be populated with the UID, and uidLength will indicate
  // if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
  success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);

  if (success) {
    // Display some basic information about the card
    Serial.println("Found an ISO14443A card");
    Serial.print("  UID Length: "); Serial.print(uidLength, DEC); Serial.println(" bytes");
    Serial.print("  UID Value: ");
    nfc.PrintHex(uid, uidLength);
    Serial.println("");

    if (uidLength == 4)
    {
      // We probably have a Mifare Classic card ...
      Serial.println("Seems to be a Mifare Classic card (4 byte UID)");

      // Now we need to try to authenticate it for read/write access
      // Try with the factory default KeyA: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF
      Serial.println("Trying to authenticate block 4 with default KEYA value");
      uint8_t keya[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

      // Start with block 4 (the first block of sector 1) since sector 0
      // contains the manufacturer data and it's probably better just
      // to leave it alone unless you know what you're doing
      success = nfc.mifareclassic_AuthenticateBlock(uid, uidLength, 4, 0, keya);

      if (success)
      {
        Serial.println("Sector 1 (Blocks 4..7) has been authenticated");
        uint8_t data[16];

        // If you want to write something to block 4 to test with, uncomment
        // the following line and this text should be read back in a minute
        // data = { 'a', 'd', 'a', 'f', 'r', 'u', 'i', 't', '.', 'c', 'o', 'm', 0, 0, 0, 0};
        // success = nfc.mifareclassic_WriteDataBlock (4, data);

        // Try to read the contents of block 4
        success = nfc.mifareclassic_ReadDataBlock(4, data);

        if (success)
        {
          // Data seems to have been read ... spit it out
          Serial.println("Reading Block 4:");
          nfc.PrintHexChar(data, 16);
          Serial.println("");

          // Wait a bit before reading the card again
          delay(1000);
        }
        else
        {
          Serial.println("Ooops ... unable to read the requested block.  Try another key?");
        }
      }
      else
      {
        Serial.println("Ooops ... authentication failed: Try another key?");
      }
    }

    if (uidLength == 7)
    {
      // We probably have a Mifare Ultralight card ...
      Serial.println("Seems to be a Mifare Ultralight tag (7 byte UID)");

      // Try to read the first general-purpose user page (#4)
      for ( int i = 6; i <= 10; i++ ) {
        Serial.print("Reading page ");
        Serial.println( i );
        uint8_t data[32];
        success = nfc.mifareultralight_ReadPage (i, data);
        if (success)
        {
          // Data seems to have been read ... spit it out
          nfc.PrintHexChar(data, 32);
          Serial.println("");

          // Wait a bit before reading the card again
          delay(5);
        }
        else
        {
          Serial.println("Ooops ... unable to read the requested page!?");
        }
      }
    }
  }
}