ESP8266 Community Forum

Posted: **Fri Dec 09, 2022 5:15 am**

I'm using nodeMCU. There are these pin S2 and S3 that represent GPIO9 and GPIO10. I want to use these pin but it does not behave like the other GPIO pin. I need help to understand what is pin S2 and S3. Please explain to me why it behave differently with the other GPIO. How can I use these two pins?

Posted: **Fri Dec 09, 2022 6:20 pm**

From information HERE it would seem that S2 & S3 are in the group of pins that are used by the board to interface with the 4MB external flash chip.

ESP8266 Community Forum

NodeMCU GPIO9 (pin S2) and GPIO10 (pin S3)

NodeMCU GPIO9 (pin S2) and GPIO10 (pin S3)

Re: NodeMCU GPIO9 (pin S2) and GPIO10 (pin S3)