Hi, I actually like your undertaking and I do think I have competencies that can assist you. Your application has become submitted. 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 in that case It's not at all mandatory since the 3V3 LDO IC1 is shielded ag