Introduction

The temperature and humidity sensor is also named DHT21, compared to the DHT11, this sensor is more accurate and more safety for it was covered with a plastic shell. The sensor measures humidity of the surrounding air by the capacitance and measures the temperature based on the use of a NTC. Note that: every data sent to the Microcontroller is the last data.

There are three wires out of the sensor, the red wire is connect to the power, the black one is connect to the ground and the rest is the single-wire. Being different from the DS18B20, it doesn’t have the serial number, can’t work together with just a port. If you wanna multiple sensors, each one must have its own data pin!

Technical data

Typical working voltage: 3.3 to 5V DC

Typical measuring current: 1.5mA

Typical current in sleeping mode: 1.1mA

Sampling period: twice a second

Features

The measure range of the temperature is -40 to +80℃

The measure range of the humidity is 0 to 99.9%RH

Precision: ±3%RH  ±0.5℃

Self calibrate

Steady 

Resource

Wiki