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Mifare MFRC522

Mifare MFRC522 RFID Reader/Writer

There are cheap RFID modules that can read and write Mifare's tags and being sold at several web stores, like eBay and included with many "starter kits" nowadays. Simply search RFID-RC522 (MF-RC522). The microcontroller and card reader uses SPI for communication (chip supports I2C and UART protocols but not implemented on library) (Maybe someone implements?). The card reader and the tags communicate using a 13.56MHz electromagnetic field. (ISO 14443A standart tags)

Datasheet for the chip that used in modules can be found at:

http://www.nxp.com/documents/data_sheet/MFRC522.pdf

Arduino MFRC522 Library from miguelbalboa at:

https://github.com/miguelbalboa/rfid

Dumping Mifare's TAGs Example:

/*
 * MFRC522 - Library to use ARDUINO RFID MODULE KIT 13.56 MHZ WITH TAGS SPI W AND R BY COOQROBOT.
 * The library file MFRC522.h has a wealth of useful info. Please read it.
 * The functions are documented in MFRC522.cpp.
 *
 * Based on code Dr.Leong   ( WWW.B2CQSHOP.COM )
 * Created by Miguel Balboa (circuitito.com), Jan, 2012.
 * Rewritten by Søren Thing Andersen (access.thing.dk), fall of 2013 (Translation to English, refactored, comments, anti collision, cascade levels.)
 * Released into the public domain.
 *
 * Sample program showing how to read data from a PICC using a MFRC522 reader on the Arduino SPI interface.
 *----------------------------------------------------------------------------- empty_skull 
 * Aggiunti pin per arduino Mega
 * add pin configuration for arduino mega
 * https://mac86project.altervista.org/
 ----------------------------------------------------------------------------- Nicola Coppola
 * Pin layout should be as follows:
 * Signal     Pin              Pin               Pin
 *            Arduino Uno      Arduino Mega      MFRC522 board
 * ------------------------------------------------------------
 * Reset      9                5                 RST
 * SPI SS     10               53                SDA
 * SPI MOSI   11               51                MOSI
 * SPI MISO   12               50                MISO
 * SPI SCK    13               52                SCK
 *
 * The reader can be found on eBay for around 5 dollars. Search for "mf-rc522" on ebay.com. 
 */

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

#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);	// Create MFRC522 instance.

void setup() {
	Serial.begin(9600);	// Initialize serial communications with the PC
	SPI.begin();			// Init SPI bus
	mfrc522.PCD_Init();	// Init MFRC522 card
	Serial.println("Scan PICC to see UID and type...");
}

void loop() {
	// Look for new cards
	if ( ! mfrc522.PICC_IsNewCardPresent()) {
		return;
	}

	// Select one of the cards
	if ( ! mfrc522.PICC_ReadCardSerial()) {
		return;
	}

	// Dump debug info about the card. PICC_HaltA() is automatically called.
	mfrc522.PICC_DumpToSerial(&(mfrc522.uid));
}

Using MFRC522 RFID with Arduino (Read And Write Tags )

http://makecourse.weebly.com/week10segment1.html

Using Arduino and RC522 Module as Door Unlocker (Control Relay To Unlock Door)

http://forum.arduino.cc/index.php?topic=256260

Extend RC522 Module's Receiver Range

http://forum.arduino.cc/index.php?topic=199983