Education

DHT11 Sensor

The DHT11 is a small and powerful sensor that can measure temperature and humidity in the air!

It works like a mini weather station inside your project! Whether it’s hot, cold, dry, or humid, the DHT11 sensor can tell you!

✅ Measures temperature in °C (Celsius) or °F (Fahrenheit)
✅ Measures humidity (how much water is in the air)
✅ Uses only one pin to send data to Arduino

The Science Behind DHT11!

The DHT11 sensor has two parts inside that help it measure temperature and humidity:

1️⃣ Temperature Sensor: Measuring Heat

• Inside the DHT11, there is a tiny thermistor (a type of resistor that changes with temperature).

• When the temperature changes, the resistance inside the thermistor changes too!

• The sensor measures this resistance and converts it into temperature data!

2️⃣ Humidity Sensor: Measuring Moisture

• The DHT11 also has a special layer that absorbs water from the air.

• When there is more water in the air (humid conditions), this layer stores more charge.

• The sensor measures this change and tells us the humidity level (0% to 100%)!

🔹 Example:
✅ If it’s raining, the humidity is high (80-100%)
✅ If you are in a desert, the humidity is low (10-20%)

Real-Life Uses of the DHT11 Sensor

1. Smart Home Systems – Your air conditioner can adjust automatically based on temperature & humidity!

2. Plant Monitoring – Helps keep plants in the right temperature & moisture conditions!

3. Weather Stations – Used in DIY weather stations to report local conditions!

4. Medical Devices – Some hospitals use it to maintain room conditions for patients!

5. IoT Smart Gadgets – Works with WiFi & Bluetooth to send data to smartphones

How to connect DHT11 Sensor on the Blue Elixer Board

Code Breakdown: DHT11 Sensor with Arduino!

Now, let’s write a program to read temperature & humidity from the DHT11 sensor and display it on the serial monitor!

#include <dht11.h>  // Include the DHT11 sensor library

#define DHT11_PIN 11  // Connect the DHT11 data pin to pin 11

dht11 DHT;  // Create a DHT object

void setup() {
  Serial.begin(9600);  // Start serial communication
}

void loop() {
  int chk = DHT.read(DHT11_PIN);  // Read temperature & humidity from DHT11

  Serial.print("Temperature: ");
  Serial.print(DHT.temperature);
  Serial.println("°C");

  Serial.print("Humidity: ");
  Serial.print(DHT.humidity);
  Serial.println("%");

  delay(2000);  // Wait 2 seconds before reading again
}

Code Breakdown (How It Works!)

1️⃣ Including the DHT11 Library

#include <dht11.h

• This library helps the Arduino communicate with the DHT11 sensor easily.

2️⃣ Defining the Sensor Pin

#define DHT11_PIN 11

• The DHT11 sensor is connected to pin 11 on the Arduino.

• We use #define so we can easily change the pin later if needed.

3️⃣ Creating the DHT Object

dht11 DHT;

• This creates a sensor object called DHT so we can read data from the sensor.

4️⃣ Setting Up Serial Communication in setup()

void setup() {
  Serial.begin(9600);  
}

• This allows the Arduino to send sensor data to your computer’s Serial Monitor!

5️⃣ Reading Temperature & Humidity in loop()

int chk = DHT.read(DHT11_PIN);

• This reads temperature & humidity from the DHT11 sensor.

6️⃣ Displaying Temperature & Humidity on Serial Monitor

Serial.print("Temperature: ");
Serial.print(DHT.temperature);
Serial.println("°C");

Serial.print("Humidity: ");
Serial.print(DHT.humidity);
Serial.println("%");

• This prints temperature & humidity data to the Serial Monitor in a readable format!

7️⃣ Adding a Delay to Avoid Rapid Readings

delay(2000);

• The DHT11 can only be read every 2 seconds, so we add a delay.

What You’ll See!

1️⃣ Open the Serial Monitor (Ctrl + Shift + M in Arduino IDE).
2️⃣ You’ll see real-time temperature & humidity readings update every 2 seconds!