Hello there, I really like your task and I think I've competencies that can assist you. Your application is submitted. 1x GND 3V3 (P2 with two pins 2.54mm) connector may be used to ability externally the WCH CH569 MCU (it is recommended to get rid of the P4/SHUNT in that circumstance It isn't obligatory as the 3V3 LDO IC1 is guarded from reverse