NCD ESP32 I2C Pins

Hardware
1

I have a couple of these NCD ESP32 boards.

They are nice because of the integrated LED, and they fit a breadboard nicely.

Per the docs, I2C would seem to be on pins SDA/37 and SCL/36

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I connected the OLED with SDA->SDA/37 and SCL->SCL/36.
In my code, i’ve tried the default ESP32 values of 21 and 22, and then 37 and 36, but cant seem to get it to find my OLED at 0x3c.

If I swap out the ESP32 for an ESP32 DEV KIT, and hook up to 21/22 on the ESP side, it works, and I can find the OLED in a simple code flow.

I am just curious what I am missing, how do I get 37/36 to act as I2C, or is 21/22 somewhere on the board.

2

when selecting the board type select adafruit feather.

3

Thank you, that worked.
I was using ESP32DEVKIT board, in Arduino IDE, for both attempts.
Once I switched to Adafruit ESp32 Feather, it worked.

Discussing with ChatGPT, it sounds like maybe the Adafruit ESP32 Feather has the I2C pins on SDA/23 and SCL/22.

I put my code back, and set the board back to the ESP32 DEVKIT, and set pins to 23/22 and it worked.

I know I should now use the Adafruit Feather ESP32 board in Arduino, but just wanted to understand why.

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