Input voltage range of the analog pins on a d1 mini

ESPHome
1

Hey,

im building my first sensor with esp home. ive got everything running and the sensor is showing realistic values, its just not calibrated. im following this tutorial https://peyanski.com/diy-ph-sensor-for-home-assistant/
its a ph sensor and the probe I got from aliexpress give an analog signal from 0-5V. the tutorial has a potentiometer build in the circuit presumable to translate the 0-5V rage to the range that the d1 mini can read.
i read that i can use either a voltage divider or a potentiometer to do this, however i cant figure out what the input range of the d1 mini is. its either 0-3.3V or 0-1V but i havent fully understood calibration process.
can someone shed some light on this ADC process?

Cheers
F.

2

The ESP8266 chip ADC is 0-1V.

Many boards include a voltage divider to make this range 0-3.3V. So it depends on the board. The D1 mini and its clones do include this.

Be aware that the ESP ADC is very non-linear at either end of its range and also that the voltage divider resistors are not precision types.

The calibrate filters may or may not be sufficient for your application:

If not an external I2C ADC is a good option.

You will need to reduce your 0-5 signal to 0-3.2V

3

great, that makes sense.
thanks for the quick response.

for the PH measurement the important range is from 4-8, that should be far enough from the ends of the PH scale

4

This may help:
400px-Wemos_A0

4 Likes