An USB isolator assists reduce ground loops and lessens electromagnetic interference (EMI) in between the pc and the linked machine.1x GND 3V3 (P2 with 2 pins 2.54mm) connector can be employed to energy externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in that case It's not at all required because the 3V3 LDO IC1 is secured ve