An USB isolator can help get rid of floor loops and reduces electromagnetic interference (EMI) amongst the pc as well as the related unit. 1x GND 3V3 (P2 with two pins 2.54mm) connector may be used to power externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT https://riverfypgx.mappywiki.com/1274897/the_definitive_guide_to_hydrabus