Its mean that we only need to connect 1 wire only? RC7(Pic) to Rx(UART) only?
How about the Tx? Not need? How to connect the ground of the UART?
Are you referring to PR8? You should refer to its schematic. For RFID reader, it will only transmit data to host (computer or microcontroller) as it can only read RFID tag's ID. So transmitting data to this type of RFID reader is meaningless. GND pin is a must for voltage reference.