Need to identify a RFID card, and allow access to a controlled space? Maybe log the time and date when a user swipes their card?
Now you can with an inexpensive (<$10) RFID solution. Just supply a Arduino, and maybe a relay to control a door strike, or a real time clock module to log date and time with the card number and user name.
We connected our RFID Module as follows:
We also connected the anode of a Red LED to pin 6 and the anode of a Green LED to Pin 5. Cathodes of each connect to a 330 ohm resistor and then to Gnd. Look in void loop() for the interesting bits.