5V DC Input

[italo]

hi, first of all thanks for the great product. it fits 100% to our requirements.

we use the board togehter with home assistant and ESPhome V 2023.5.2.

We like to messure Temperature via NTC sensors. We use this settings.

10K NTC
9.89K resistor
5V DC Power Supply
Connected on INA1

We get a wrong temperature reading. If we connect the 5V DC direkt to the  INA1 input we get max. 3.03V on the GPIO36. As we see you use a LMxxx bevor the ESP32. Is the conversion of the 5V linear
to the 3.3V input of the ESP32? Do you have any hints? as the  reference_voltage we use 3V because of the limitation of the ESP32.

BR
Giuseppe

ESPHome Code: 

sensor:
  -  platform:  ntc
     sensor:  resistance_sensor
     name:  NTC Temperature
     id: INA1_TEMP
     calibration:
      b_constant: 3950
      reference_temperature: 25°C
      reference_resistance: 10kOhm
   
  # Example source sensors:
  - platform: resistance
    id: resistance_sensor
    sensor: INA1
    configuration: DOWNSTREAM
    resistor: 9.89kOhm
    reference_voltage: 3V
    name: Resistance Sensor

  - platform: adc
    id: INA1
    pin: GPIO36
    attenuation: auto
    update_interval: 5s
    name: "INA1"

[admin]

can you draw paper how you wire. we can test it as your wires.

[italo]

hi, attached the file as requested.

[admin]

   
   
   
After a simple simulation, the voltage should change, but our reference voltage may not be the standard 3.3V, so it needs to be calibrated.
The 0-5V incoming signal is divided by 1% precision resistors on the board, the voltage follows, and the limiter enters the ESP32 ADC port.
NTC10K This circuit may not be sensitive to temperatures below 20 degrees, so it cannot be tested