An USB isolator allows eradicate floor loops and minimizes electromagnetic interference (EMI) involving the computer along with the related unit.1x GND 3V3 (P2 with 2 pins 2.54mm) connector can be employed to power 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 i