An USB isolator allows eradicate floor loops and minimizes electromagnetic interference (EMI) involving the computer along with the connected system. 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 that case It's https://eu-pentestlab.co/en/