Does anyone tested this kind of rf sensor SPI ?
http://www.ebay.com/itm/Mifare-RC522-Card-RFID-Reader-IC-Card-RF-Proximity-Module-SPI-Arduino-STM32-AVR-/330886790933?pt=LH_DefaultDomain_0&hash=item4d0a63bf15
http://www.ebay.com/itm/Mifare-RC522-Card-RFID-Reader-IC-Card-RF-Proximity-Module-SPI-Arduino-STM32-AVR-/330886790933?pt=LH_DefaultDomain_0&hash=item4d0a63bf15