ESP32 RC522 RFID/NFC Module

Code Examples

Below you can find code examples of RC522 RFID/NFC Module with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

If you encounter issues while using the RC522 RFID/NFC Module, check the Common Issues Troubleshooting Guide.

ESP32 RC522 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the RC522 RFID/NFC Module:

#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN 9
#define SS_PIN 10
MFRC522 rfid(SS_PIN, RST_PIN);

void setup() {
    Serial.begin(115200);
    SPI.begin();
    rfid.PCD_Init();
    Serial.println("RC522 initialized. Waiting for cards...");
}

void loop() {
    if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
        delay(50);
        return;
    }

    Serial.print("Card UID: ");
    for (byte i = 0; i < rfid.uid.size; i++) {
        Serial.print(rfid.uid.uidByte[i], HEX);
        Serial.print(" ");
    }
    Serial.println();

    rfid.PICC_HaltA();
}

This Arduino sketch interfaces with the RC522 module over SPI using the MFRC522 library. The `setup` function initializes the module, while the `loop` scans for RFID cards and prints their UIDs when detected. Additional functionality, such as reading or writing card data, can be implemented using the MFRC522 library.

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 RC522 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the RC522 RFID/NFC Module, here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include "driver/spi_master.h"
#include "driver/gpio.h"
#include "freertos/task.h"
#include "rc522.h"

#define RST_PIN GPIO_NUM_21
#define SS_PIN GPIO_NUM_22
#define MISO_PIN GPIO_NUM_19
#define MOSI_PIN GPIO_NUM_23
#define SCK_PIN GPIO_NUM_18

void app_main() {
    printf("Initializing RC522...");
    rc522_config_t config = {
        .spi_miso_io = MISO_PIN,
        .spi_mosi_io = MOSI_PIN,
        .spi_sck_io = SCK_PIN,
        .spi_cs_io = SS_PIN,
        .reset_io = RST_PIN
    };

    rc522_handle_t handle = rc522_create(&config);
    if (handle == NULL) {
        printf("Failed to initialize RC522\n");
        return;
    }

    while (true) {
        rc522_tag_t tag;
        if (rc522_read_tag(handle, &tag) == ESP_OK) {
            printf("Tag UID: ");
            for (int i = 0; i < tag.uid_size; i++) {
                printf("%02X ", tag.uid[i]);
            }
            printf("\n");
        }
        vTaskDelay(pdMS_TO_TICKS(500));
    }
}

This ESP-IDF code initializes the RC522 RFID module over SPI. The module continuously scans for RFID tags and logs their UIDs. The `rc522_read_tag` function retrieves tag information when available. Additional functionalities like writing to cards can be implemented using the RC522 driver.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 RC522 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the RC522 RFID/NFC Module

spi:
  clk_pin: GPIO18
  mosi_pin: GPIO23
  miso_pin: GPIO19

rc522:
  cs_pin: GPIO22
  rst_pin: GPIO21
  update_interval: 2s

sensor:
  - platform: rc522
    uid:
      name: "RFID Tag UID"
    log:
      name: "RFID Log"

This ESPHome configuration sets up the RC522 RFID module over SPI. The module is updated every 2 seconds to scan for RFID tags. Detected tag UIDs are logged and available as a sensor output. The configuration can be extended for writing to tags or using the tag data in automations.

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 RC522 PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:rc522]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

ESP32 RC522 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the RC522 RFID/NFC Module:

#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN 21
#define SS_PIN 22
MFRC522 rfid(SS_PIN, RST_PIN);

void setup() {
    Serial.begin(115200);
    SPI.begin();
    rfid.PCD_Init();
    Serial.println("RC522 initialized. Waiting for cards...");
}

void loop() {
    if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
        delay(50);
        return;
    }

    Serial.print("Card UID: ");
    for (byte i = 0; i < rfid.uid.size; i++) {
        Serial.print(rfid.uid.uidByte[i], HEX);
        Serial.print(" ");
    }
    Serial.println();

    rfid.PICC_HaltA();
}

This PlatformIO example interfaces with the RC522 module using the MFRC522 library over SPI. The code initializes the module, scans for RFID tags, and logs their UIDs to the Serial Monitor. Additional NFC features can be implemented using the library.

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 RC522 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the RC522 RFID/NFC Module with your ESP32.

from machine import Pin, SPI
from mfrc522 import MFRC522
import time

spi = SPI(1, baudrate=1000000, sck=Pin(18), mosi=Pin(23), miso=Pin(19))
rst = Pin(21, Pin.OUT)
cs = Pin(22, Pin.OUT)

reader = MFRC522(spi, cs, rst)

while True:
    print("Waiting for card...")
    (status, tag_type) = reader.request(reader.REQIDL)

    if status == reader.OK:
        (status, uid) = reader.anticoll()
        if status == reader.OK:
            print("Card UID:", [hex(i) for i in uid])
    time.sleep(1)

This MicroPython example uses the MFRC522 library to interface with the RC522 module over SPI. It continuously scans for RFID tags, and when detected, prints their UIDs. Additional functionalities, such as reading or writing data to cards, can be added using the library.

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.