API reference summary

1. Constructor and transport

#include <Wire.h>
#include <Electroniccats_PN7150.h>

Electroniccats_PN7150 nfc(4, 5, 0x28, PN7160);
//                      IRQ, VEN, address, device

The library's class name is Electroniccats_PN7150, including when used with PN7160. Pass the explicit PN7160 selector; do not omit the fourth constructor argument.

nfc.setI2CPins(8, 9) selects SDA8 and SCL9 on ESP32-S3. Call it before connectNCI(). The address is 7-bit; the factory-open ADR0 and ADR1 pads select 0x28.

2. Initialization

Set Wire.setClock(400000UL) after connectNCI() or begin() succeeds. These methods initialize the I2C bus. Set the clock again if your recovery code closes and restarts the bus.

The software power preset does not detect the applied voltage. VCC supports 3.3–5.5 V, while the module's host signals use 3.3 V logic. See supply configuration before changing power sources.

3. Tag detection and recovery

If discovery recovery fails, stop tag operations, verify the supply and bus, and perform a controller reset through VEN before reconnecting. Use bounded retries rather than an uncontrolled reset loop.

4. Read the correct identifier length

These accessors return pointers. Do not use sizeof(pointer) as the identifier length. In library 3.1.3, the NFC-V display branch in DetectTags uses this pattern, so its printed identifier may be incomplete. For a working copy of that example, print all eight NFC-V identifier bytes and keep the byte order consistent with your application.

if (nfc.remoteDevice.getModeTech() == nfc.tech.PASSIVE_NFCV) {
  const unsigned char* id = nfc.remoteDevice.getID();
  for (uint8_t i = 0; i < 8; ++i) {
    if (id[i] < 0x10) Serial.print('0');
    Serial.print(id[i], HEX);
    if (i < 7) Serial.print(':');
  }
  Serial.println();
}

The snippet prints the identifier in the order returned by the library. A displayed identifier is not an authentication result or a complete read of the card's protected data.

5. Basic ESP32-S3 sketch

This basic NFC-A identifier example uses SDA8, SCL9, IRQ4, VEN5, address 0x28 and a 3.3 V module supply. For 5.0 V VCC, change the preset argument to false; the GPIOs remain 3.3 V logic.

#include <Wire.h>
#include <Electroniccats_PN7150.h>

Electroniccats_PN7150 nfc(4, 5, 0x28, PN7160);
bool readerReady = false;

void setup() {
  Serial.begin(115200);
  delay(1000);
  nfc.setI2CPins(8, 9);
  nfc.setPn7160FixedVbat3V3(true);  // Module VCC = 3.3 V

  if (nfc.connectNCI()) {
    Serial.println("NCI connection failed");
    return;
  }
  Wire.setClock(400000UL);

  if (nfc.configureSettings() || nfc.configMode() || nfc.startDiscovery()) {
    Serial.println("NFC initialization failed");
    return;
  }
  readerReady = true;
  Serial.println("Present an NFC-A tag");
}

void loop() {
  if (!readerReady) {
    delay(100);
    return;
  }
  if (!nfc.isTagDetected(250)) return;

  if (nfc.remoteDevice.getModeTech() == nfc.tech.PASSIVE_NFCA) {
    const unsigned char* id = nfc.remoteDevice.getNFCID();
    const uint8_t length = nfc.remoteDevice.getNFCIDLen();
    Serial.print("NFC-A ID: ");
    for (uint8_t i = 0; i < length; ++i) {
      if (id[i] < 0x10) Serial.print('0');
      Serial.print(id[i], HEX);
      if (i + 1 < length) Serial.print(':');
    }
    Serial.println();
  }

  nfc.waitForTagRemoval();
  readerReady = nfc.reset();
  if (!readerReady) Serial.println("Discovery restart failed");
}

If initialization or discovery restart fails, this sketch stops NFC activity. Correct the wiring or supply issue and restart the host; add application-specific recovery and user feedback before deployment.

6. Further APIs

For NDEF and card memory operations, follow the corresponding repository example and the full API reference. Use writable test cards for write operations, and check authentication, memory bounds and card-specific commands.

Low-level readerTagCmd() does not take a reply-buffer capacity argument. Allocate and validate buffers for the intended command and response; do not pass unchecked application data to the low-level interface.