Introduction

The PN532 NFC RFID Module V3 is a highly integrated transmission module for 13.56MHz contactless communication. Based on NXP's PN532 chipset, it supports read/write operations with various NFC and RFID tags including Mifare, NTAG, and FeliCa.

Key Features

Technical Specifications

Pin Configuration

Pin	Label	Description	Arduino Connection
1	VCC	Power (3.3V or 5V)	5V
2	GND	Ground	GND
3	SDA	I2C Data	A4
4	SCL	I2C Clock	A5
5	IRQ	Interrupt Request	D2
6	RST	Reset	D3

Wiring with Arduino (I2C)

// Basic I2C Connections:
// VCC → 5V
// GND → GND
// SDA → A4 (SDA)
// SCL → A5 (SCL)
// IRQ → D2 (optional)
// RST → D3 (optional)

// For SPI interface, different connections are required

Basic Tag Reading Example

// PN532 NFC Reader Basic Example (using Adafruit_PN532 library)
#include <Wire.h>
#include <Adafruit_PN532.h>

#define PN532_IRQ   (2)
#define PN532_RESET (3)

Adafruit_PN532 nfc(PN532_IRQ, PN532_RESET);

void setup() {
  Serial.begin(9600);
  nfc.begin();
  
  uint32_t versiondata = nfc.getFirmwareVersion();
  if (!versiondata) {
    Serial.println("PN532 not found");
    while (1);
  }
  
  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 NFC tag...");
}

void loop() {
  uint8_t success;
  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };
  uint8_t uidLength;
  
  success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);
  
  if (success) {
    Serial.println("Found NFC tag!");
    Serial.print("UID Length: "); Serial.print(uidLength, DEC); Serial.println(" bytes");
    Serial.print("UID Value: ");
    for (uint8_t i=0; i < uidLength; i++) {
      Serial.print(" 0x"); Serial.print(uid[i], HEX);
    }
    Serial.println();
    delay(1000);
  }
}

Advanced Features

// Configure as NFC tag
nfc.setPassiveActivationRetries(0xFF);
nfc.startPassiveTargetIDDetection(PN532_MIFARE_ISO14443A);

// Authenticate with Mifare Classic
uint8_t keya[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
success = nfc.mifareclassic_AuthenticateBlock(
  uid, uidLength, 4, 0, keya);

// Write NDEF URL to NTAG
uint8_t ndefprefix = NDEF_URIPREFIX_HTTP;
uint8_t url[] = { 'e', 'k', 'o', 's', 't', 'r', 'a', '.', 'c', 'o', 'm' };
success = nfc.ntag2xx_WriteNDEFURI(ndefprefix, url, sizeof(url));

// Initialize NFC P2P
nfc.InitDepTarget();
// Configure as Initiator/Target
nfc.TgInitAsTarget();

Troubleshooting