DHT21 Digital Temperature and Humidity Sensor With Arduino

In this tutorial we will learn how to use DHT21 Humidity and Temperature Sensor with Arduino and display the values on the OLED Display.Watch the video!

Step 1: What You Will Need

• Arduino Uno or any other Arduino board
• DHT21 sensor
• Breadboard
• Jumper wires
• OLED Display
• Visuino software: Download here

Step 2: The Circuit

• Connect DHT21 positive pin + (VCC) to Arduino pin +5V
• Connect DHT21 negative pin - (GND) to Arduino pin GND
• Connect DHT21 pin (Out) to Arduino digital pin (7)
• Connect OLED Display pin[VCC] to Arduino pin[5V]
• Connect OLED Display pin[GND] to Arduino pin[GND]
• Connect OLED Display pin[SDA] to Arduino pin[SDA]
• Connect OLED Display pin[SCL] to Arduino pin[SCL]

Step 3: Start Visuino, and Select the Arduino UNO Board Type

The Visuino: https://www.visuino.eu also needs to be installed. Download Free version or register for a Free Trial.

Start Visuino as shown in the first picture Click on the "Tools" button on the Arduino component (Picture 1) in Visuino When the dialog appears, select "Arduino UNO" as shown on Picture 2

Step 4: In Visuino Add,Set & Connect Components

• Add "DHT" component
• Select "HumidityThermometer1" and in the properties window set type to DHT21
• Add "OLED" display component
• Double click on the "DisplayOLED1"
• In the elements window drag "Text Field" to the left side
• In the properties window set size to 2
• In the elements window drag another "Text Field" to the left side
• In the properties window set size to 2 and Y to 20
• Close the Elements window
• Connect "HumidityThermometer1" pin Temperature to "DisplayOLED1" > "Text Field1"
• Connect "HumidityThermometer1" pin Humidity to "DisplayOLED1" > "Text Field2"
• Connect "HumidityThermometer1" pin Sensor to Arduino board DIGITAL pin 7
• Connect "DisplayOLED1" pin I2C Out to Arduino board pin I2C In

Step 5: Generate, Compile, and Upload the Arduino Code

In Visuino, at the bottom click on the "Build" Tab, make sure the correct port is selected, then click on the "Compile/Build and Upload" button.

Step 6: Play

If you power the Arduino UNO module, the OLED Display will start to show the temperature and humidity values.

Congratulations! You have completed your project with Visuino. Also attached is the Visuino project, that I created for this tutorial, you can download it and open it in Visuino: https://www.visuino.eu