How to Use DHT-22 Sensor - Arduino Tutorial





Introduction: How to Use DHT-22 Sensor - Arduino Tutorial

The DHT-22 (also named as AM2302) is a digital-output relative humidity and temperature sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin.

In this tutorial you will learn how to use this sensor with Arduino uno. The room temperature & humidity will be printed to serial monitor.

So, let's get started!

Step 1: About the DHT-22 Sensor

The DHT22 is a basic, low-cost digital temperature and humidity sensor. 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).

Connections are simple, 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.

Technical details:

  • Power: 3-5V
  • Max Current: 2.5mA
  • Humidity: 0-100%, 2-5% accuracy
  • Temperature: -40 to 80°C, ±0.5°C accuracy

Step 2: What You Will Need

For this tutorial you will need:

  • Arduino uno
  • Breadboard
  • DHT-22

Step 3: The Circuit

The connections are pretty easy, see the image above with the breadboard circuit schematic.

Step 4: The Code

Here's the code, embedded using codebender!

Try downloading the codebender plugin and clicking on the "Run on Arduino" button to program your Arduino board with this sketch. Below you will also find codebender serial monitor, press connect button to start receiving data from sensor.

Step 5: Well Done!

You have successfully completed one more Arduino "How to" tutorial and you learned how to use the DHT-22 sensor.

I hope you liked this, let me know in the comments.

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Don't you need a 10k resistor in there?

as a pullup on the data line and 5v

Hi!, I am Jay and want to ask about the problem which i faced. I connected everything perfectly, codes were also perfect but then i uploaded the code onto the Intel Galileo Gen2 board and found out that no humidity and temperature is measured perfectly through serial monitor. it says " Humidity = 0% Temperature = 0.00C". Please help me out.

is ur sensor connected to digital pin 2

Can this project be used in conjunction with a WeMo switch to turn on/off a furnace based on the humidity of that space?

use a relay board and the if function. As long as ur furnace has some sort of electric starting and stopping mechanism (electric heating system).

Otherwise you will have to think of a handy mech to turn on and off the furnace mechanically and electrically.

if (humidity > 60)


digitalWrite(relayPin, HIGH);



digitalWrite(relayPin, LOW);


But Great Project I already made it!

Where I should get the DHT22.h Library?


probably need to add these lines:
#include <DHT.h>
#include <DHT_U.h>
#include <Adafruit_Sensor.h>

and first install Adafruit Dht22 and somekind of Unified Sensor library from the library manager

and the other weird thing that i noticed, lol...:
you cant have any backup copies of the same sketch file in the same folder, otherwise you get a redefinition error?:o