An USB isolator will help remove 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 energy externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in that case https://lemmyj940sja5.ziblogs.com/profile