Q: GPIO electrical level status

[ESP_Greg]

Q: GPIO electrical level status

XPD_DCDC is output as high level. Except it, rest GPIO can config as input high level.
About GPIO default status after booting: except 6 SDIO/GPIO4/GPIO5/GPIO16, rest GPIO all have internal pull-up resistor.
If config as low level, need external pull-low or inverting circuits triode.

PS: GPIO can't connect to 5V.
GPIO4/5can't be full-up to high level with external 1M resistor; you need 100K resistor instead. As attachment showed.