Departments:
  1. Electrical Engineering
  2. Electronics Engineering
  3. Mechatronics Engineering
Sensors:
  1. DHT22
Softwares:
  1. Proteus
introduction to dht22, dht22 pinout, dht22 arduino interfacing, dht22 working, dht22
Hello friends, I hope you are all fine and will be doing something interesting in your life. in today's post, I am going to discuss Introduction to DHT22. It is a temperature and humidity measure sensing device. It is easily used but it needs a specific time for an operation. Its temperature measuring range is from -40 to +125 degrees Celsius with +-0.5 accuracy. This sensor measures moisture content and temperature. This sensor is easily connected to other microcontrollers. DHT22 plays an important role in our environment in measuring temperature and moisture. It is a low cost easy-to-use small sensor. This sensor is used at different weather stations to measure temperature and ratio of moisture in the air, in this way, they tell about temperature or rain prediction. In today's post, I will talk about its working protocol, pinout, application and interfacing with other microcontrollers. I will also share some links to projects where I have interfaced with other Arduino. If you have any queries about it please ask in the comment I will resolve your queries. So let's start with Introduction to DHT22.

Introduction to DHT22

  • DHT22 is a low-cost humidity and temperature measuring sensor. It consists of thermister for temperature measurement and capacitive humidity sensor humidity measurement. The feature which gives importance then another sensor is that you can get data after two seconds.
  • It is very easy to use, just connect the first pin from left with supply then get data from the second pin. Its last pin used for ground.
  • It has higher accuracy and precision, due to this feature it can replace expensive imported SHT10 temperature and humidity sensor.
  • This sensor is used to measure environment temperature and humidity to meet the high demand.
  • This sensor has reliability and good stability. It is easy to combine with a special sensor Arduino expansion board, which is easy to use for temperature and humidity perception.
  • DHT22 is digital humidity sensor, designed for analog sensor interfacing.
  • It consists of 4.7 K to 10 K resistor, which can be used as pull up from data pin to Vcc.
  • It has four pins with 0.1" spacing.
For better understanding now discuss its pin configuration.

DHT22 PINOUT & Description

There is main four pinout of DHT22 we use three pins which are discussed below with details.
No. Pin Type                                         Parameters
1. Vcc This is Power Pin at this pin we apply 3.5 v to 5.0 volts.
2 Data Through this pin, we get outputs both Temperature and Humidity through serial Data.
3 Ground Ground Pin ( Connected to 0V or GND )
Better understanding lets see its pinout picture.
introduction to dht22, dht22 pinout, dht22 arduino interfacing, dht22 working, dht22
Now discuss its working and its principle at which it works.

Working of DHT22

  • Now discuss how it works, It consists of two main parts one measure temperature and other is used for humidity measurement it also has IC to send data to Microcontroller. Discuss these component ones by one.
    •  Humidity Sensing Component
      • For humidity measurement, it uses the humidity measurement component, which has two electrodes with moisture holding substrate between them.
      • As humidity changes, the conductivity of substrate changes or resistance between electrodes changes. This changes in resistance are measured, then processed by IC which make it ready to be rad by Microcontroller.
    • Temperature Measuring Component
      • To measure temperature this sensor uses an NTC temperature sensor or Thermistor.
      • A thermistor is a variable resistor that changes its resistance with a change of temperature. These sensors are made by sintering of semiconductive materials, such as ceramic or polymers in order to large change in a resistor with small changes in temperature. As temperature changes, there is a change in the value of resistance by which we measure the temperature of our environment.
For a better understanding of its working, Lets its picture.
introduction to dht22, dht22 pinout, dht22 arduino interfacing, dht22 working, dht22
Now, discuss the features and specifications of DHT22.

Features & Specification of DHT22

These are some features of DHT22.
  • The voltage it operates is 3.5v to 5.5v.
  • Its operating current is 0.3v to 5.5.
  • The protocol which it uses to send data is a serial transmission of data.
  • Its temperature at which it operates is -40°C to 80°C.
  • Its humidity range is 0% to 100%.
  • Its temperature and humidity resolution are 16-bit.
  • Its Accuracy is ±0.5°C and ±1%
  • Its sampling rate is 0.5 Hz once every two seconds.
  • Its dimensions are 27mm x 59mm x 13.5mm (1.05" x 2.32" x 0.53").
  • It has four pins with 0.1" spacing.
  • Its weight is 2.4g.
  • It is a low-cost sensor. Its price is just $1 to $5.
  • It has long term stability of ±0.5% per year.
Now we discuss the DHT22 Serial Data Transmission protocol by which it sends data.

DHT22 Serial Protocol

  • DHT22 sensor is calibrated in industries it is designed for serial output data transmission. I have to interface it with Microcontroller for its serial data transmission.
  • As you can see that the data pin is connected with an input-output pin of Microcontroller and 5k pull up resistor is used. This data pin sends output values of both temperature and humidity as serial data.
For a better understanding of serial transmission, let's see its picture.
introduction to dht22, dht22 pinout, dht22 arduino interfacing, dht22 working, dht22
Now discuss DHT22 Arduino interfacing.

DHT22 Arduino Interfacing

  • In given circuit diagram I have interfaced Arduino with DHT22. By providing source code to Arduino we can use it according to desire requirement and also can use it for temperature and humidity measuring purpose.
    introduction to dht22, dht22 pinout, dht22 arduino interfacing, dht22 working, dht22

Application of DHT22

These are some application of DHT22.
  • It is used for temperature and humidity measurement.
  • It is used as a weather station to measure temperature and humidity in the air.
  •  It is an automatic climate control sensor.
  • It is also used as an environmental monitoring device.
So, friends, this was all about DHT22, if you have any query regarding it please ask in a comment. I will resolve your queries. Thanks for reading. Take care until the next tutorial.....