I tried to read Standard Mifare card using PN532 board with Arduino Nano, but instead it reads my code

Question

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_PN532.h>

//Interfacing dengan mode SPI
#define PN532_SCK  (13)
#define PN532_MOSI (11)
#define PN532_SS   (10)
#define PN532_MISO (12)
Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

void setup(void) {
  Serial.begin(115200);
  nfc.begin();
  uint32_t versiondata = nfc.getFirmwareVersion();
  if (! versiondata) {
    Serial.print("Didn't find PN53x board");
    while (1); // halt
  }
  // configure board to read RFID tags
  nfc.SAMConfig();

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


void loop(void) {
  uint8_t success;                          // Flag to check if there was an error with the PN532
  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)
  uint8_t currentblock;                     // Counter to keep track of which block we're on
  bool authenticated = false;               // Flag to indicate if the sector is authenticated
  uint8_t data[16];                         // Array to store block data during reads

  // Keyb on NDEF and Mifare Classic should be the same
  uint8_t keyuniversal[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

  // 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 or 7)
    {
      // Now we try to go through all 16 sectors (each having 4 blocks)
      // authenticating each sector, and then dumping the blocks
      for (currentblock = 0; currentblock < 64; currentblock++)
      {
        // Check if this is a new block so that we can reauthenticate
        if (nfc.mifareclassic_IsFirstBlock(currentblock)) authenticated = false;

        // If the sector hasn't been authenticated, do so first
        if (!authenticated)
        {
          // Starting of a new sector ... try to to authenticate
          Serial.print("------------------------Sector ");Serial.print(currentblock/4, DEC);Serial.println("-------------------------");
          if (currentblock == 0)
          {
              // This will be 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF for Mifare Classic (non-NDEF!)
              // or 0xA0 0xA1 0xA2 0xA3 0xA4 0xA5 for NDEF formatted cards using key a,
              // but keyb should be the same for both (0xFF 0xFF 0xFF 0xFF 0xFF 0xFF)
              success = nfc.mifareclassic_AuthenticateBlock (uid, uidLength, currentblock, 1, keyuniversal);
          }
          else
          {
              // This will be 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF for Mifare Classic (non-NDEF!)
              // or 0xD3 0xF7 0xD3 0xF7 0xD3 0xF7 for NDEF formatted cards using key a,
              // but keyb should be the same for both (0xFF 0xFF 0xFF 0xFF 0xFF 0xFF)
              success = nfc.mifareclassic_AuthenticateBlock (uid, uidLength, currentblock, 1, keyuniversal);
          }
          if (success)
          {
            authenticated = true;
          }
          else
          {
            Serial.println("Authentication error");
          }
        }
        // If we're still not authenticated just skip the block
        if (!authenticated)
        {
          Serial.print("Block ");Serial.print(currentblock, DEC);Serial.println(" unable to authenticate");
        }
        else
        {
          // Authenticated ... we should be able to read the block now
          // Dump the data into the 'data' array
          success = nfc.mifareclassic_ReadDataBlock(currentblock, data);
          if (success)
          {
            // Read successful
            Serial.print("Block ");Serial.print(currentblock, DEC);
            if (currentblock < 10)
            {
              Serial.print("  ");
            }
            else
            {
              Serial.print(" ");
            }
            // Dump the raw data
            nfc.PrintHexChar(data, 64);
          }
          else
          {
            // Oops ... something happened
            Serial.print("Block ");Serial.print(currentblock, DEC);
            Serial.println(" unable to read this block");
          }
        }
      }
    }
    else
    {
      Serial.println("Ooops ... this doesn't seem to be a Mifare Classic card!");
    }
  }
  // Wait a bit before trying again
  Serial.println("\n\nSend a character to run the mem dumper again!");
  Serial.flush();
  while (!Serial.available());
  while (Serial.available()) {
  Serial.read();
  }
  Serial.flush();
}

I use that code and changing the data length that i want to read in this line

nfc.PrintHexChar(data, 64);

When I tried to use 64 byte (i didn't exactly sure it is byte or bit) or lower it seems to be fine, but when i tried bigger number it will dump my code too.

Here the log when I tried to dump 128 byte of data

Waiting for an ISO14443A Card ...
Found an ISO14443A card
  UID Length: 4 bytes
  UID Value: 0xD0 0x8E 0x1C 0x1B

------------------------Sector 0-------------------------
Block 0  D0 8E 1C 1B 59 08 04 00 62 63 64 65 66 67 68 69 D0 8E 1C 1B 00 00 00 FF FF FF FF FF FF 59 09 F8 08 00 00 00 69 00 90 00 00 FF 06 FA D5 00 00 FF 00 FF 00 00 00 37 04 80 00 FF FF FF FF FF FF 00 00 00 00 36 01 96 00 C3 00 9E 01 F4 00 D2 00 E6 00 00 00 00 00 CB 04 9E 04 FF 04 74 04 97 04 84 04 75 04 0D 0A 00 44 69 64 6E 27 74 20 66 69 6E 64 20 50 4E 35 33 78 20 62 6F 61 72 64 00 57 61  Ў..Y...bcdefghiЎ.....⸮⸮⸮⸮⸮⸮Y.Y....i.⸮..⸮.⸮⸮..⸮.⸮...7.⸮.⸮⸮⸮⸮⸮⸮....6.⸮.⸮.⸮.⸮.⸮.⸮.....⸮.⸮.⸮.t.⸮.⸮.u....Didn't find PN53x board.Wa
Block 1  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 D0 8E 1C 1B 00 00 00 FF FF FF FF FF FF 59 09 F8 08 00 00 00 69 00 90 00 00 FF 06 FA D5 00 00 FF 00 FF 00 00 00 37 04 80 00 FF FF FF FF FF FF 00 00 00 00 36 01 96 00 C3 00 9E 01 F4 00 D2 00 E6 00 00 00 00 00 CB 04 9E 04 FF 04 74 04 97 04 84 04 75 04 0D 0A 00 44 69 64 6E 27 74 20 66 69 6E 64 20 50 4E 35 33 78 20 62 6F 61 72 64 00 57 61  ................Ў.....⸮⸮⸮⸮⸮⸮Y.Y....i.⸮..⸮.⸮⸮..⸮.⸮...7.⸮.⸮⸮⸮⸮⸮⸮....6.⸮.⸮.⸮.⸮.⸮.⸮.....⸮.⸮.⸮.t.⸮.⸮.u....Didn't find PN53x board.Wa
Block 2  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 D0 8E 1C 1B 00 00 00 FF FF FF FF FF FF 59 09 F8 08 00 00 00 69 00 90 00 00 FF 06 FA D5 00 00 FF 00 FF 00 00 00 37 04 80 00 FF FF FF FF FF FF 00 00 00 00 36 01 96 00 C3 00 9E 01 F4 00 D2 00 E6 00 00 00 00 00 CB 04 9E 04 FF 04 74 04 97 04 84 04 75 04 0D 0A 00 44 69 64 6E 27 74 20 66 69 6E 64 20 50 4E 35 33 78 20 62 6F 61 72 64 00 57 61  ................Ў.....⸮⸮⸮⸮⸮⸮Y.Y....i.⸮..⸮.⸮⸮..⸮.⸮...7.⸮.⸮⸮⸮⸮⸮⸮....6.⸮.⸮.⸮.⸮.⸮.⸮.....⸮.⸮.⸮.t.⸮.⸮.u....Didn't find PN53x board.Wa
Block 3  00 00 00 00 00 00 FF 07 80 69 FF FF FF FF FF FF D0 8E 1C 1B 00 00 00 FF FF FF FF FF FF 59 09 F8 08 00 00 00 69 00 90 00 00 FF 06 FA D5 00 00 FF 00 FF 00 00 00 37 04 80 00 FF FF FF FF FF FF 00 00 00 00 36 01 96 00 C3 00 9E 01 F4 00 D2 00 E6 00 00 00 00 00 CB 04 9E 04 FF 04 74 04 97 04 84 04 75 04 0D 0A 00 44 69 64 6E 27 74 20 66 69 6E 64 20 50 4E 35 33 78 20 62 6F 61 72 64 00 57 61  ......⸮.⸮i⸮⸮⸮⸮⸮⸮Ў.....⸮⸮⸮⸮⸮⸮Y.Y....i.⸮..⸮.⸮⸮..⸮.⸮...7.⸮.⸮⸮⸮⸮⸮⸮....6.⸮.⸮.⸮.⸮.⸮.⸮.....⸮.⸮.⸮.t.⸮.⸮.u....Didn't find PN53x board.Wa

Welcome to SO. That function seems to dump data is located in the buffer you provide. If you pass a length that is not related to the size of that buffer, you will dump whatever is found in memory adjacent to that buffer. You should check what size you read from your device and only print that size. From your description I would assume 64 (or evenless) is the size of your real data. You should check your manual to see what size is read by `mifareclassic_ReadDataBlock` — Gerhardh, Jun 29 '21 at 09:14
Thank you for the answer. By any chance, is there any way that I can use to find how much length i can pass to that buffer? I actually used different card (not really know the base of, if it's Mifare's or not) for my project. — Ant.Kuma, Jun 29 '21 at 09:19
I am not familiar with that stuff. Therefore I just added a comment. There must be some size mentioned in the spec of your cards which you have to use. If your cards have different block sizes, that would require to first identify the card and then pick correct size. But looking at your code again (`uint8_t data[16];`), you are not allowed to read or write more than 16 bytes with that buffer. Any larger number will cause illegal out of bounds accesses. — Gerhardh, Jun 29 '21 at 09:23
This seems potentially helpful: https://forum.arduino.cc/t/nfc-and-pn532-library-read-a-single-byte-from-a-specific-page/464930 — enhzflep, Jun 29 '21 at 12:10

I tried to read Standard Mifare card using PN532 board with Arduino Nano, but instead it reads my code

0 Answers0