Pt100 and esp32

Dear
I wanted to ask you the following, a while ago I made a device with blynk and a nodemcu ESP8266 the interface to connect a PT100 industrial sensor, because the sensor works resistively, and is powered with 24V, I connected it to port A0 through of a bridge formed by a 220ohm resistor (connecting on side A the negative output of PT100 and A0, and on side B -24V of the source and GND. Then with a digital sensor I simultaneously measured the temperature and the values from the PT100, and I made an interpolation. I then used this interpolation in an Arduino code to read the data from the PT100 with BLYNK. It works quite well. A0 is 8 bits, I have interpolated values ​​from 0 to 1024.
The problem is that I need to do the same with the ESP32, but in principle in addition to using a different scale from the ADC 0 to 4095, with several resistors I have tried and the results are not fixed like the esp8266, but vary, it seems prone to noise , and I have also read that it must be closed. I would like to know if anyone has any ideas to make it work well with the PT100.
first of all, Thanks…

RUBEN MEDINA.
• Hardware model ESP32

First of all, you have to choose the right analog pin on the ESP32. To use it with WiFi (and therefore Blynk) it needs to one that’s connected to ADC1…

  • ADC1_CH0 (GPIO 36)
  • ADC1_CH1 (GPIO 37)
  • ADC1_CH2 (GPIO 38)
  • ADC1_CH3 (GPIO 39)
  • ADC1_CH4 (GPIO 32)
  • ADC1_CH5 (GPIO 33)
  • ADC1_CH6 (GPIO 34)
  • ADC1_CH7 (GPIO 35)

You can change the resolution to 0-1024 (which is actually 10 bit resolution) or use the default 12 bit resolution of 0-4095.
You can also set the attenuation too, but you might need to modify your voltage divider to get useable results.
The ESP8266 has an analog input voltage range of 0-3.3v and even with maximum attenuation the ESP32 has an analog input range of 0-2.6v

ESP32 Analog Input with Arduino IDE | Random Nerd Tutorials.

Pete.