PN532 Complete Guide

PN532 Complete Guide: NXP's Most Popular NFC Controller

The PN532 is NXP's most widely deployed NFC nfc-controller for hobbyist and prototyping use. Released in 2007, it remains the default choice for Arduino, Raspberry Pi, and ESP32 NFC projects because of its mature library ecosystem and dual-interface (I2C + SPI + HSU) support.

PN532 at a Glance

Hardware Interface Selection

The PN532 exposes three interfaces simultaneously but activates only one based on the I0/I1 pin states at power-up:

Most breakout boards (Adafruit PN532, Elechouse v3) provide DIP switches or solder jumpers for I0/I1. SPI is the fastest and most reliable for long cable runs. I2C allows address configuration but is limited to ~400 kHz and sensitive to bus capacitance.

Connecting to Arduino

SPI wiring (recommended):

Install the Adafruit PN532 library via Library Manager. The library abstracts the TFI (Transport Frame Interface) framing and handles the PN532's acknowledgement handshake automatically.

#include <Adafruit_PN532.h>
#define PN532_SS 10
Adafruit_PN532 nfc(PN532_SS);

void setup() {
    nfc.begin();
    nfc.SAMConfig();  // Configure the Secure Access Module
}

void loop() {
    uint8_t uid[7];
    uint8_t uidLength;
    if (nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength)) {
        // Tag detected
    }
}

Connecting to Raspberry Pi

On Raspberry Pi, use the I2C or SPI interface via the GPIO header.

I2C setup: 1. Enable I2C: sudo raspi-config → Interface Options → I2C → Enable 2. Install libnfc: sudo apt install libnfc-bin libnfc-dev 3. Configure /etc/nfc/libnfc.conf:

device.name = "PN532 I2C"
device.connstring = "pn532_i2c:/dev/i2c-1"

1. Test: nfc-list — should print connected tags

The Python nfcpy library also supports the PN532 and provides a higher-level ndef read/write API:

import nfc

def on_connect(tag):
    print(tag.ndef.message)

with nfc.ContactlessFrontend('i2c') as clf:
    clf.connect(rdwr={'on-connect': on_connect})

Supported Tag Operations

Raw APDU Commands

For Type 4 tags and DESFire, the PN532 passes ISO 7816 APDUs directly. Use InDataExchange to send APDUs and receive responses:

uint8_t apdu[] = {0x00, 0xA4, 0x04, 0x00, 0x07,
                  0xD2, 0x76, 0x00, 0x00, 0x85, 0x01, 0x01, 0x00};
uint8_t response[64];
uint8_t responseLen = sizeof(response);
nfc.inDataExchange(apdu, sizeof(apdu), response, &responseLen);

Performance Tuning

PN532 vs Alternatives

Common Issues and Fixes

See Also

• NFC Arduino and Raspberry Pi Guide
• PN7150 NFC Controller Guide
• ST25R NFC Reader IC Guide
• NFC Security Deep Dive
• Chip Selector