The HTU21D is a low-cost, easy to use, highly accurate, digital humidity and temperature sensor. This sensor is ideal for environmental sensing and data logging and perfect for a weather stations or humidor control systems. All you need is two lines for I2C communication and you’ll have relative humidity readings and very accurate temperature readings as a bonus!
There are only four pins that need to be hooked up in order to start using this sensor in a project. One for VCC, one for GND, and two data lines for I2C communication. This breakout board has built in 4.7k pull up resistors for I2C communications. If you’re hooking up multiple I2C devices on the same bus, you may want to disable these resistors.
-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
-Only one HTU21D sensor can reside on the I2C bus at a time
Automotive: defogging, HVAC