ESP8266 GPIO pins info, restrictions and features

done :wink: ESP32 GPIO pins info, restrictions and features


Hi, and thanks for your efforts!
With respect it seems your SCL and SDA labels need to be reversed.
I am using an SHT31 Sensor on a NodeMCU 0,9 board with an ESP8266-12S, and it is working Ok.
Pins are as follows:-
D1 GPIO5 SCL green wire
D2 GPIO4 SDA yellow wire
Hope this helps!

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GPIO2 may depends on the board, as well as how hard you pull the signal โ€œdownโ€. For example, pulling GPIO2 low on an ESP01S with an impedance of 10 kohm will cause boot to fail. GPIO2 behaves similar to GPIO1 on an ESP01S with micropython loaded. One difference is GPIO2 has 1 or 2 kohm resistor and LED on GPIO2 on the ESP01S, which prevents the 100 k pulldown from bring the input lower than about 1 V - although, that appears to still read as 0 for input, but may not have much noise immunity.

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