An USB isolator allows eradicate floor loops and minimizes electromagnetic interference (EMI) involving the computer along with the connected unit. 1x GND 3V3 (P2 with 2 pins 2.54mm) connector may be used to power externally the WCH CH569 MCU (it is usually recommended to remove the P4/SHUNT in that situation https://finnwphzq.wikievia.com/10297807/5_simple_statements_about_hydrabus_explained