ESP32 pin-out question

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1

Hey guys! I have the following ESP32 and I have to connect multiple sensors to it. So far, all my sensors required digital pins , and I’ve used pins like GPIO 32 33 25 etc, both as input and outputs.
I have a sensor for soil moisture that requires analog input, so I can read his values and map it so I have a percentage display. I tried different pins and none works , and I got really confused which ones I can actually use for analog input data.
The reading I get is 4095 , probably because all pins output 3.3V and converted to digital is 4095.

So, which pins can I use to read analog values ?

Thanks

ESP32-WeMos-LOLIN32-pinout-mischianti
ESP32-WeMos-LOLIN32-pinout-mischianti1679×921 465 KB

2

Hi,

the image you posted shows which ADC channel is connected to which GPIO. For example the ADC1 channel 0 is connected to GPIO36. So make sure that you use the correct ADC1/2 AND channel depending on the GPIO you want to use.

You also may check that there is no external Pull-Up or similar connected to the used GPIO.
If you are using a capacitive moisture sensor it’s possible that the voltage for “dry” is same as the sensor input voltage. Therefore 4095 (max. ADC count on 12 bit resolution) could be correct if the sensor is dry or laying around and outputs 3.3V.

Greetings,
Julian