DuncanWilliam77:
Is there a way I can add code to time for how long the rfid tag is within read range of the reader? ie time for how long the rfid reader voltage is high
The datasheet seems to indicate a 2.7 kHz square wave appears on the 'buzzer' pin when a card is present. It is not clear if the signal continues until the card is removed. If it does, you could use that signal. Is there a LED on the board that lights up (and stays lit) when a card is present? You might be able to tap into the signal that drives the LED.