Arduino library for the STMicroelectronics CR95HF 13.56 MHz NFC/RFID transceiver.

• ISO14443-A (NFC-A) protocol support
• 4-byte and 7-byte UID detection
• Automatic anticollision handling
• SAK-based card type identification
• Built-in self-test and diagnostics
• Debug output option

Tested on:

• ESP32C6

• MIFARE Classic 1K/4K
• MIFARE Mini
• MIFARE Ultralight
• NTAG21x series (213, 215, 216)
• MIFARE Plus
• MIFARE DESFire
• Other ISO14443-A compatible tags

The CR95HF must be configured for UART mode:

UART Configuration:

• Baud rate: 57600
• Data bits: 8
• Stop bits: 2 (critical!)
• Parity: None

Warning: The CR95HF requires 2 stop bits (8N2). Using 8N1 will cause communication failures.

1. Open Arduino IDE
2. Go to Sketch → Include Library → Manage Libraries
3. Search for "CR95HF"
4. Click Install

1. Download this repository as ZIP
2. In Arduino IDE: Sketch → Include Library → Add .ZIP Library
3. Select the downloaded ZIP file

#include <CR95HF.h>

// ESP32-C6 example pins
#define NFC_RX_PIN  1
#define NFC_TX_PIN  2
#define NFC_BAUD    57600

CR95HF nfc(Serial1, NFC_RX_PIN, NFC_TX_PIN, NFC_BAUD);

void setup() {
    Serial.begin(115200);

    if (!nfc.begin()) {
        Serial.println("CR95HF init failed!");
        while (1);
    }

    Serial.println("CR95HF ready");
}

void loop() {
    uint8_t uid[10];
    uint8_t uidLen, sak;

    if (nfc.iso14443aGetUID(uid, uidLen, sak)) {
        // Print UID
        Serial.print("Tag: ");
        for (int i = 0; i < uidLen; i++) {
            if (uid[i] < 0x10) Serial.print('0');
            Serial.print(uid[i], HEX);
            if (i < uidLen - 1) Serial.print(':');
        }

        // Print card type
        Serial.print(" (");
        Serial.print(nfc.getCardType(sak));
        Serial.println(")");
    }

    delay(150);
}

CR95HF(HardwareSerial& port, int rxPin, int txPin, uint32_t baudRate);

• TagReader - Basic tag reading example

1. Check wiring connections
2. Verify SSI_0 and SSI_1 are tied to GND
3. Ensure correct RX/TX pin assignment (TXD→RX, RXD→TX)
4. Verify 3.3V power supply

1. Run nfc.selfTest() to check RF field
2. Verify antenna connection
3. Try different tag types
4. Check for interference (metal surfaces)

1. Increase retry count in your code
2. Adjust scan interval
3. Check antenna coupling distance

• None.

• CR95HF Datasheet
• ISO14443-3A Standard
• NXP MIFARE Type Identification (AN10833)

Copyright (c) 2025 B4E SRL. All rights reserved.

David Baldwin - B4E SRL