It’s a significant update. The Arduino UNO and Arduino Mega 2560 update the Duemilanove and Mega respectively. They now use an ATMega8U2 instead of an FTDI USB to serial converter chip.

I just received my RC522 RFID reader ... is the Arduino pin where we connect the button that is used the reset the alarm. The relay is connected to pin 7 and the active buzzer to pin 8. On the next ...