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
/* * 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)); }
http://makecourse.weebly.com/week10segment1.html
http://forum.arduino.cc/index.php?topic=256260