HTU21D Humidity Sensor Hookup Guide

Contributors: Nate

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HTU21D Overview

The HTU21D is a low-cost, easy to use, highly accurate, digital humidity sensor. All you need is two lines for I2C communication and you’ll have relative humidity readings such as “45.2%” or “23.1%” and very accurate temperature readings as a bonus!

HTU21D Breakout Board

Things you should know about this sensor:

  • Uses the I2C interface
  • Typical humidity accuracy of ±2%
  • Typical temperature accuracy of ±0.3C
  • Operates from 0 to 100% humidity but this sensor isn’t recommended for harsh environments where it could come in contact with water (such as rain).
  • 3.3V sensor - use inline logic level converters or 10k resistors to limit 5V signals
  • Here’s the datasheet
  • Only one HTU21D sensor can reside on the I2C bus at a time

This sensor is ideal for environmental sensing and data logging. Perfect for a weather station or humidor control system. It is a very good replacement for digital humidity sensors such as the SHT15, SHT21, SHT25, HIH-4030, HIH6130 and capacitive humidity sensors such as the HH10D.

Suggested Reading

Things you might need to know:


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