ESP32-CAM does not boot with DS18B20 on GPIO14

[muller59]

Hello,
i want to use the ESP32-CAM from AI_thinker to monitor my 3D printer enclosure.
I also want to know the temperature within the enclosure.

When i enhance the standard example CameraWebServer with code to read the DS18B20 temp sensor, this compiles without error.
However, the ESP32-CAM does not boot with gpio14 connected to the DS18B20. the gpio14 is pulled up with a 4K7 resistor (ds18b20 requirement).
when i disconnect gpio14, the ESP32-CAM boots
then i connect gpio14, and the ESP32-CAM starts reading the sensor, so the code works.

i am not using any card in the ESP32-CAM

does anyone have an idea why the ESP32-CAM will not boot with gpio14 connected.
Is gpio14 the right io to use? It seems free on the AI_thinker board.

thanks for reading,
Rob

[username]

Are you using the SD card with your application ?
IO14 is the HS2_CLK signal for the SD Card socket.

[muller59]

No, i am not using the SD card.

i am just curious which gpio port is free to use on the ESP32-CAM, all ports that are accessible via header seem to be spoken for.

Thanks for the reaction.

[bobtidey]

I don't know why GPIO14 would affect the boot unless it is something to do with the camera software. Maybe try it with a minimal sketch to see if that boots OK with GPIO14 pulled up.

On my camera app I do use the SD card so there is little IO free. I use RXD as GPIO3 pin; just use pinMode in setup.. This doesn't stop serial debug if required. I am sure you could use this for your temp sensor.

[Chuma87]

Hi, try using GPIO_13

I have a doppler sensor and it works great