ESP32 and DFRobot PT100 module

[fabc09]

I've bought a Gravity: Analog High Temperature Sensor with included a PT100 probe (https://www.dfrobot.com/product-1474.html) (https://wiki.dfrobot.com/HighTemperatur ... KU_SEN0198).

I'm trying to use it with an ESP32 with DFRobot library (https://github.com/nxcosa/HighTemperatureSensor) and the results are far from correct.

At ambient temperature a DS18B20 is measuring 18-18.1 °C while the PT100 is measuring between 7 and 9°C.

In the code I select 3.3 V (same voltage as ESP32 output)

#include<DFRobotHighTemperatureSensor.h>
const float voltageRef = 3.300; //Set reference voltage,you need test your IOREF voltage.

Do you have any idea how to solve ?

Thanks a lot