The reader initializes the interaction. The RF area is activated, and several other low level instructions are exchanged to detect a compatible card. 1x GND 3V3 (P2 with 2 pins 2.54mm) connector may be used to power externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in https://hydrabus16284.blogocial.com/5-essential-elements-for-hydrabus-68950823