Using an PN532 RFID reader

What is the difference between an PN532 RFID reader and an MFRC522 RFID reader

The PN532 and MFRC522 are two popular RFID reader modules, each with its own features and use cases.

In this tutorial, we will be using a PN532 module from DFRobot, if you are using an MFRC522 module, please refer to this tutorial. This tutorial is adapted from here.

RFID Tag

Aside from the regular card, there are more options than before, including stickers, button tags etc.

Wiring

Switch
This tutorial will be using the i2c communication protocol, make sure you switch to IIC on the module.

1. D/T - SDA (Pin 14)
2. C/R - SCL (Pin 15)
3. GND - GND (Ground)
4. VCC to 5V (Power)

Library

We will be using the DFRobot_PN532 library. Please see this tutorial to learn how to install libraries.

Getting started

The number of blocks of data depends on the type of RFID tag or card you’re using. Most commonly, the MIFARE Classic card is used, which is compatible with both the PN532 and MFRC522. A standard MIFARE Classic 1K card will have 64 blocks of data and the smaller NTAG213 tag will have 36 blocks of data.

Some blocks are read-only, so you cannot write data to those blocks. For example, Block 0 usually contains the UID (Unique Identifier) and other manufacturer data, and is read-only.

The below codes are only for writing to and reading the data from Block 3.

Write Data

#include <DFRobot_PN532.h>

#define  BLOCK_SIZE         16
#define  PN532_IRQ          2
#define  INTERRUPT          1
#define  POLLING            0
// The block to be written
#define  WRITE_BLOCK_NO      3

DFRobot_PN532_IIC  nfc(PN532_IRQ, POLLING);

uint8_t dataWrite[BLOCK_SIZE] = {"your message"}; //change to your data

void setup() {
  Serial.begin(115200);
  Serial.print("Initializing");
  while (!nfc.begin()) {
    Serial.print(".");
    delay (1000);
  }
  Serial.println();
  Serial.println("Waiting for a card......");
}
void loop() {
  // For S50 card/tag, block 1-2, 4-6, 8-10, 12-14... 56-58, 60-62 are for user data
  // You can read/write these blocks freely.
  // Use "MifareClassic_ReadAllMemory.ino" to check all the blocks
  if (nfc.scan()) {
    if (nfc.writeData(WRITE_BLOCK_NO, dataWrite) != 1) {
      Serial.print("Block ");
      Serial.print(WRITE_BLOCK_NO);
      Serial.println(" write failure!");
    }
    else {
      Serial.print("Block ");
      Serial.print(WRITE_BLOCK_NO);
      Serial.println(" write success!");
      Serial.print("Data written(string):");
      Serial.println((char *)dataWrite);
      Serial.print("Data written(HEX):");
      for (int i = 0; i < BLOCK_SIZE; i++) {
        Serial.print(dataWrite[i], HEX);
        Serial.print(" ");
      }
    }
  }
  delay(500);
}

Read Data

#include <DFRobot_PN532.h>

#define BLOCK_SIZE       16
#define  PN532_IRQ        2
#define  INTERRUPT        1
#define  POLLING          0
// The block to be read
#define  READ_BLOCK_NO    3

DFRobot_PN532_IIC  nfc(PN532_IRQ, POLLING);
uint8_t dataRead[16] = {0};

void setup() {
  pinMode(13,OUTPUT);
  Serial.begin(115200);
  Serial.print("Initializing");
  while (!nfc.begin()) {
    Serial.print(".");
    delay (1000);
  }
  Serial.println();
  Serial.println("Waiting for a card......");
  
}
void loop() {
  // For S50 card/tag, block 1-2, 4-6, 8-10, 12-14... 56-58, 60-62 are for user data
  // You can read/write these blocks freely.
  // Use "MifareClassic_ReadAllMemory.ino" to check all the blocks
  if (nfc.scan()) {
    if (nfc.readData(dataRead, READ_BLOCK_NO) != 1) {
      Serial.print("Block ");
      Serial.print(READ_BLOCK_NO);
      Serial.println(" read failure!");
    }
    else {
      Serial.print("Block ");
      Serial.print(READ_BLOCK_NO);
      Serial.println(" read success!");

      Serial.print("Data read(string):");
      String data = (char *)dataRead;
      Serial.println(data);

/*
      //interaction
      if(data == "your message" ){
        digitalWrite(13, HIGH);
        
        }else{
          digitalWrite(13, LOW);
          }
*/
/*
      //in hex
      Serial.print("Data read(HEX):");
      for (int i = 0; i < BLOCK_SIZE; i++) {
        Serial.print(dataRead[i], HEX);
        Serial.print(" ");
        dataRead[i] = 0;
      }
      Serial.println();
*/
    }
   
    delay(500);
  }
}