Rfid-Rc522 Wiring Diagram. I'm having trouble connecting an rc522 rfid reader to my esp32 module. One straight and one bent to 90. Arduino RFID Karten from www.aeq-web.com Rfid interfacing with 8051 microcontroller. This can be anywhere from 2.5 to 3.3 volts. There is a 3.3 volt pin on arduino where it can be connected.