Table of Contents

HTS221 - Capacitive digital sensor for relative humidity and temperature

Some of the applications mentioned by the datasheet:

  • Air conditioning, heating and ventilation
  • Air humidifiers
  • Refrigerators
  • Wearable devices
  • Smart home automation
  • Industrial automation
  • Respiratory equipment
  • Asset and goods tracking



Important: make sure you properly setup the I2C pins especially for ESP32 before creating the I2cDevice, make sure you install the nanoFramework.Hardware.ESP32 nuget:

// when connecting to an ESP32 device, need to configure the I2C GPIOs
// used for the bus
Configuration.SetPinFunction(21, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(22, DeviceFunction.I2C1_CLOCK);

For other devices like STM32, please make sure you're using the preset pins for the I2C bus you want to use.

using System;
using System.Threading;
using System.Device.I2c;
using Iot.Device.Common;
using Iot.Device.Hts221;
using UnitsNet;

// I2C address on SenseHat board
const int I2cAddress = 0x5F;

using Hts221 th = new(CreateI2cDevice());
while (true)
    var tempValue = th.Temperature;
    var humValue = th.Humidity;

    Debug.WriteLine($"Temperature: {tempValue.DegreesCelsius:0.#}\u00B0C");
    Debug.WriteLine($"Relative humidity: {humValue:0.#}%");

    // WeatherHelper supports more calculations, such as saturated vapor pressure, actual vapor pressure and absolute humidity.
    Debug.WriteLine($"Heat index: {WeatherHelper.CalculateHeatIndex(tempValue, humValue).DegreesCelsius:0.#}\u00B0C");
    Debug.WriteLine($"Dew point: {WeatherHelper.CalculateDewPoint(tempValue, humValue).DegreesCelsius:0.#}\u00B0C");

I2cDevice CreateI2cDevice()
    I2cConnectionSettings settings = new(1, I2cAddress);
    return I2cDevice.Create(settings);