Module information for MFRC-522, low cost RFID card operating at 13.56MHz 3.3V

Where to Buy http://www.aliexpress.com/item/10set-MFRC-522-RC522-RFID-RF-IC-card-sensor-module-to-send-S50-Fudan-card-keychain/1617235161.html
Currently [Dec 2014] 10 for $28.70 ~ $2.87 each roughly and these come with one Card and one Keyring RFID tag as well as the pins to solder.
Info <a href="https://labitat click to read.dk/wiki/RFID_RC522-AN”>https://labitat.dk/wiki/RFID_RC522-AN
Important to Note

Try not to be placed between the card reader and the reader when any metal objects. So as not to affect the results.

Model: MF522-AN, read-write data, based on NPX chip MFRC522.
Aproximate detection distance = 10 cms.
Voltage: 3.3 volts @ 13 ma. Maximum current = 30 ma.
Specification Tag: Mifare MF1S503 with 1 Kb EEPROM
Interface: 8-pin header connector, SPI, with speed up to 10 Mbps

SPI Info http://www.puntoflotante.net/SPI-TUTORIAL.pdf
Operating Temperature: -20 to +60 degrees C.
Dimensions: 40 x 60 mm.

  • Model:MIFARE RC522
  • Sleep Current:<80uA
  • Peak current:<30mA
  • Operating Frequency:13.56MHz
  • Read Range:0~45mm
  • Baud Rate:115200
 MISO MOSI SCK
Extending Range:

Set RFCfgReg to 48db gain. That should get you through an average door.

 Connected to Mobile tutorial / information 
 Code  Git Hub – Arduino Library https://github.com/miguelbalboa/rfid
Arduino http://playground.arduino.cc/Learning/MFRC522

 

The following table shows the typical pin layout used:

 

PCD

Arduino

MFRC522

Uno

Mega

Nano v3

Signal

Pin

Pin

Pin

Pin

RST/Reset

RST

9 [1]

5 [1]

D9

SPI SS

SDA [3]

10 [2]

53 [2]

D10

SPI MOSI

MOSI

11 / ICSP-4

52

D11

SPI MISO

MISO

12 / ICSP-1

51

D12

SPI SCK

SCK

13 / ICSP-3

50

D13

[1]

(1, 2) Configurable, typically defined as RST_PIN in sketch/program.

[2]

(1, 2) Configurable, typically defined as SS_PIN in sketch/program.

[3]

The SDA pin might be labeled SS on some/older MFRC522 boards.

code I was using for a project, needs editing

https://github.com/cmoz/RC522_RFID-Yun/blob/master/RC522_Uno.ino