simulate this circuit – Schematic created using CircuitLab
MCU1 is factory and I can't modify its firmware. I need to add a second MCU2 (ESP32) to control existing 4-20 sensor. Which ADC can I use here?
Are there any variants to use the ESP32's internal ADC? Isolated DC-DC does not solve the problem because I also need to sniff the UART port of MCU1.
Ground is car body here.