How to Measure Humidity and Temperature with DHT22 Sensor and Arduino

Difficulty Level: Beginner

Learn how to measure humidity and temperature using the DHT22 sensor and an Arduino. This easy-to-follow tutorial explains the wiring, code, and optional LCD integration to display real-time readings.

Components Required

• Arduino Uno
• DHT22 Temperature and Humidity Sensor
• 10k Ohm Resistor
• 16x2 LCD (optional)
• Breadboard and Jumper Wires

Step 1: Wiring the Circuit

Follow these steps to connect the DHT22 sensor to the Arduino:

• VCC (Pin 1) - Arduino 5V
• GND (Pin 4) - Arduino GND
• DATA (Pin 2) - Arduino Digital Pin 2 (with a 10k pull-up resistor between DATA and VCC)

Step 2: Arduino Code

#include "DHT.h"

#define DHTPIN 2        // Pin where the DHT22 data pin is connected
#define DHTTYPE DHT22   // DHT 22 (AM2302)

DHT dht(DHTPIN, DHTTYPE);

void setup() {
    Serial.begin(9600);
    dht.begin();
    Serial.println("DHT22 sensor reading started");
}

void loop() {
    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();

    if (isnan(humidity) || isnan(temperature)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
    }

    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.print(" %\t");
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" *C");

    delay(2000);
}
        

Optional: Display on LCD

To display the sensor readings on an LCD, use the code below:

#include 
#include "DHT.h"

#define DHTPIN 2
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
    lcd.begin(16, 2);
    dht.begin();
    lcd.print("DHT22 Sensor");
    delay(1000);
}

void loop() {
    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();

    if (isnan(humidity) || isnan(temperature)) {
        lcd.setCursor(0, 1);
        lcd.print("Sensor error");
        return;
    }

    lcd.setCursor(0, 0);
    lcd.print("Temp: ");
    lcd.print(temperature);
    lcd.print(" C");

    lcd.setCursor(0, 1);
    lcd.print("Humidity: ");
    lcd.print(humidity);
    lcd.print(" %");

    delay(2000);
}
        

Step 3: Testing the DHT22 Sensor

Upload the code to your Arduino and open the Serial Monitor. You should see real-time temperature and humidity readings. If connected, the LCD will also display the sensor values.

Conclusion

By following this tutorial, you've successfully created a humidity and temperature monitoring system using the DHT22 sensor and Arduino. This project is ideal for weather stations, IoT applications, or home automation.