https://randomnerdtutorials.com/esp8266 ... h-nodemcu/
Currently, TOUT (Pin6) has a 10-bit precision and its input voltage range is 0 to 3.3V when TOUT is connected to an external circuit.
Note: with earlier versions of the ESP, the A0 pin operated at maximum voltage of 1.0V, so check your board A0 voltage before following the next circuit.
The author of that page is using a ESP-07 and a ESP-12E.
I am not sure which version of the ESP module I want to get yet, but I want to know:
firstly, is that page correct at all? (with respect to there being different analog reference voltages with different ESP modules)
second, if it is correct, is there a definitive reference that I can check what is the actual analog reference for each module version?
third, what is the actual maximum voltage that can be applied to the TOUT pin 6, with a resistor divider that gives about 10kohm of impedance, before there is a permanent hardware failure? (I am not asking for the maximum it can read, I am asking for the maximum it can survive, of course I read the datasheet and it did not state this information)
Thanks