ESP8266-MFRC522

MFRC522 RFID module connected to ESP8266 (ESP-12) WiFi module

Many thanks to nikxha from the ESP8266 forum

Requirements

You have to install the Arduino IDE 1.6.4.

Arduino > Preferences > "Additional Boards Manager URLs:" and add: http://arduino.esp8266.com/package_esp8266com_index.json
Arduino > Tools > Board > Boards Manager > type in ESP8266 and install the board
download MFRC522 module (see Libraries) and copy folder to Arduino library path

Libraries

RFID library by Miguel Balboa

Wiring RFID RC522 module

I have to update the picture. It seems that not all ESP boards working with wiring on picture. In this case - please use following wiring:

MISO - GPIO12 (hw spi)
MOSI - GPIO13 (hw spi)
SCK  - GPIO14 (hw spi)
SS   - GPIO04 (free GPIO)
RST  - GPIO05 (free GPIO)

define RFID module

#include "MFRC522.h"
#define RST_PIN	5 // RST-PIN for RC522 - RFID - SPI - Modul GPIO5 
#define SS_PIN	4 // SDA-PIN for RC522 - RFID - SPI - Modul GPIO4 
MFRC522 mfrc522(SS_PIN, RST_PIN);	// Create MFRC522 instance

Initialize RFID module

void setup() {
  Serial.begin(9600);    // Initialize serial communications
  SPI.begin();	         // Init SPI bus
  mfrc522.PCD_Init();    // Init MFRC522
}

Read RFID tag

void loop() { 
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    delay(50);
    return;
  }
  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    delay(50);
    return;
  }
  // Show some details of the PICC (that is: the tag/card)
  Serial.print(F("Card UID:"));
  dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
  Serial.println();
}

// Helper routine to dump a byte array as hex values to Serial
void dump_byte_array(byte *buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
    Serial.print(buffer[i], HEX);
  }
}