The HTU21D is a lowcost, easy to use, accurate digital humidity and temperature sensor. It is suitable for environmental sensing and data logging, and is a practical choice for weather stations or humidor control systems. Key specifications Power supply voltage: 1.5 to 3.6 V Humidity measurement range: 0 to 100 % RH Temperature measurement range: 40 C to 105 C Interface and readings Communication: I2C twowire interface With two data lines for I2C communication, you obtain relative humidity readings and accurate temperature readings Pinout and wiring Requires four pins to operate: VCC, GND, SDA, SCL Benefits and compatibility Digital output simplifies integration with microcontrollers via I2C Minimal wiring with a fourpin connection for quick prototyping Provides reliable humidity and temperature data for environmental monitoring Use scenarios Weather station data logging to monitor ambient humidity and temperature Humidor environment control to maintain appropriate humidity and temperature levels Greenhouse or indoor environmental monitoring for climate management