GPIOs dont work as generic

[arcbtc]

Using 38-27 for a 4x4 keypad, but they dont seem to work as generic ESP32 GPIOS Using "Keypad" library Same code works fine with DEVKIT V1 and NODEMCU 32S

const byte rows = 4; //four rows
const byte cols = 3; //three columns
char keys[rows][cols] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[rows] = {27, 26, 25, 33}; //connect to the row pinouts of the keypad
byte colPins[cols] = {32, 39, 38}; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, rows, cols );

[arcbtc]

Pin 38, 39 seem to be the issue

[lewisxhe]

@arcbtc 38,39 can only be configured as an input. If you confirm that it is pressed by detecting low level, please use a pull-up resistor to pull the PIN high externally.

[billmetz]

From the IO_MUX table of the ESP32 Datasheet (V3.3), GPIO34 to GPIO39 are input only. Perhaps it would be helpful to update TTGO-pinmap.jpg as :

[tadam777]

You're right pins GPIO34 to GPIO39 are input only.

Link to the ESP32 datasheet

[xpix]

Well, what to say about it. A PCB design for the garbage can ... thanks for the tip to all.

[yngndrw]

I've just fallen into this trap as well, like you I now have a load of useless PCBs.

It's clearly labeled as GPIO on the pinout so I'm very annoyed by it.

[stevempotter]

You can unsolder a couple of tiny caps on the underside to get those GPIOs back. (C49, C32)