I just received my RC522 RFID reader and made this simple Arduino access control system that uses the reader, a buzzer for the alarm and a relay shield for the security system. The relay can be used ...

So the TX and RX leds are driven by a couple of pins on the ATmega32U4 (see a comment on the hardware connection below) to make it look like they are on the serial bus. They were not intended to be ...