RC522 RFID/NFC Module

// Requires the rc522 driver from the ESP Component Registry:
//   idf.py add-dependency "abobija/rc522^4.0.0"

#include <stdio.h>
#include "rc522.h"
#include "driver/rc522_spi.h"
#include "rc522_picc.h"

#define MISO_GPIO 19
#define MOSI_GPIO 23
#define SCLK_GPIO 18
#define CS_GPIO   5   // SS, matches the wiring above
#define RST_GPIO  4   // RST, matches the wiring above

static rc522_spi_config_t driver_config = {
    .host_id = SPI3_HOST,
    .bus_config = &(spi_bus_config_t){
        .miso_io_num = MISO_GPIO,
        .mosi_io_num = MOSI_GPIO,
        .sclk_io_num = SCLK_GPIO,
    },
    .dev_config = {
        .spics_io_num = CS_GPIO,
    },
    .rst_io_num = RST_GPIO,
};

static rc522_driver_handle_t driver;
static rc522_handle_t scanner;

static void on_picc_state_changed(void *arg, esp_event_base_t base, int32_t event_id, void *data)
{
    rc522_picc_state_changed_event_t *event = (rc522_picc_state_changed_event_t *)data;
    rc522_picc_t *picc = event->picc;

    if (picc->state == RC522_PICC_STATE_ACTIVE) {
        char uid_str[RC522_PICC_UID_STR_BUFFER_SIZE_MAX];
        rc522_picc_uid_to_str(&picc->uid, uid_str, sizeof(uid_str));
        printf("Card detected, UID: %s\n", uid_str);
    }
}

void app_main(void)
{
    ESP_ERROR_CHECK(rc522_spi_create(&driver_config, &driver));
    ESP_ERROR_CHECK(rc522_driver_install(driver));

    rc522_config_t scanner_config = {
        .driver = driver,
    };
    ESP_ERROR_CHECK(rc522_create(&scanner_config, &scanner));
    ESP_ERROR_CHECK(rc522_register_events(scanner, RC522_EVENT_PICC_STATE_CHANGED, on_picc_state_changed, NULL));
    ESP_ERROR_CHECK(rc522_start(scanner));
}

spi:
  clk_pin: GPIO18
  mosi_pin: GPIO23
  miso_pin: GPIO19

rc522_spi:
  cs_pin: GPIO5    # SDA/SS, matches the wiring above
  reset_pin: GPIO4 # RST
  update_interval: 1s
  on_tag:
    - logger.log:
        format: "Tag scanned: %s"
        args: ['x.c_str()']

binary_sensor:
  - platform: rc522
    uid: 74-10-37-94  # replace with your tag's UID (see the log line above)
    name: "RC522 Known Tag"

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
    miguelbalboa/MFRC522 @ ^1.4.12

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

#define RST_PIN 4 // GPIO4, matches the wiring above
#define SS_PIN 5  // GPIO5 (SDA/SS); SCK=GPIO18, MISO=GPIO19, MOSI=GPIO23 (ESP32 VSPI defaults)
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();
}

# Requires driver: mfrc522.py from https://github.com/wendlers/micropython-mfrc522
# Copy it to the board: mpremote cp mfrc522.py :
from mfrc522 import MFRC522
import time

# Pins per the wiring above: SCK 18, MOSI 23, MISO 19, RST 4, CS (SDA/SS) 5
reader = MFRC522(sck=18, mosi=23, miso=19, rst=4, cs=5)

while True:
    (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(0.5)