5. DHT22 - Digital Temperature and Humidity Sensor

5.1. Description

The DHT22 is a low-cost digital temperature and humidity sensor with a single wire digital interface. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed).

The sensor is calibrated and doesn’t require extra components so you can get the right to measuring relative humidity and temperature.

It is quite simple to use but requires careful timing to grab data. You can only get new data from it once every 2 seconds.

DHT22 - AM2302DHT22 - AM2302

DHT22 - AM2302

5.2. How it works?

Connect the first pin on the left to 3-5V power, the second pin to your data input pin and the right most pin to ground.

📘

Note

Although it uses a single-wire to send data it is not Dallas One Wire compatible! If you want multiple sensors, each one must have its own data pin!

5.3. Technical details

Model

DHT22/AM2302

Power supply

3.3-6V DC

Output signal

Digital signal via 1-wire bus

Sensing element

Polymer capacitor

Operating range

Humidity 0-100%RH;
Temperature -40~80Celsius

Accuracy

Humidity +-2%RH(Max +-5%RH);
Temperature <+-0.5Celsius

Resolution or sensitivity

Humidity 0.1%RH;
Temperature 0.1Celsius

Repeatability

Humidity +-1%RH;
Temperature +-0.2Celsius

Humidity hysteresis

+-0.3%RH

Long-term stability

+-0.5%RH/year

Sensing period

Average: 2s

Interchangeability

Fully interchangeable

Dimensions

Small size 14185.5mm;
Big size 22285mm

5.4. Data sheet

4.5. Where to buy?