The ESP32 Mini uses a CP2104 UART module to drive the USB port. The CP2104 is configured in self-powered mode, which means that even if nothing is plugged into the USB port and the board is powered by a 3.3V source, it is still drawing ~100uA of current. I wanted to see the effect of removing this module on the power consumption of my test circuit.
Removing the UART module means losing access to the USB port. However, I should still be able to program it using a standard FTDI programmer, which I wanted to verify. So I took out the same FTDI programmer that was used for programming the ESP8266, and built a custom holder for the ESP32 Mini.
- ESP32 VIN <-> FTDI 3.3V
- ESP32 GND <-> FTDI GND
- ESP32 TX <-> FTDI RX
- ESP32 RX <-> FTDI TX