Note

Hello, welcome to the SunFounder Raspberry Pi & Arduino & ESP32 Enthusiasts Community on Facebook! Dive deeper into Raspberry Pi, Arduino, and ESP32 with fellow enthusiasts.

Why Join?

  • Expert Support: Solve post-sale issues and technical challenges with help from our community and team.

  • Learn & Share: Exchange tips and tutorials to enhance your skills.

  • Exclusive Previews: Get early access to new product announcements and sneak peeks.

  • Special Discounts: Enjoy exclusive discounts on our newest products.

  • Festive Promotions and Giveaways: Take part in giveaways and holiday promotions.

πŸ‘‰ Ready to explore and create with us? Click [here] and join today!

2.32 DHT11 Module

Overview

In this lesson, you will learn how to use DHT11 Module. The DHT11 is a basic, ultra 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 are needed).

Components Required

../_images/Part_two_32.png

Fritzing Circuit

In this example, we can directly connect the pins of DHT11 Module to the pins of Mega 2560 Board, and we use pin 4 to read the signal of DHT11 Module. Connect the pinγ€Œ+」of DHT11 Module to 5V, the pinγ€Œ-」 to GND, and the pin OUT to pin 4.

../_images/image241.png

Wiring Diagram

../_images/image242.png

Code

Note

  • You can open the file 2.32_dhtModule.ino under the path of sunfounder_vincent_kit_for_arduino\code\2.32_dhtModule directly.

  • The DHT sensor library library is used here, you can install it from the Library Manager.

    ../_images/lib_dht11.png

After the codes are uploaded to the Mega2560 board, the serial monitor will continue to output the current temperature and humidity values of the environment.

Code Analysis

  1. Includes the DHT.h library, which provides functions to interact with the DHT sensors. Then, set the pin and type for the DHT sensor.

    #include "DHT.h"

#define DHTPIN 4  // Set the pin connected to the DHT11 data pin
#define DHTTYPE DHT11 // DHT 11

DHT dht(DHTPIN, DHTTYPE);

  2. Initializes serial communication at a baud rate of 115200 and initializes the DHT sensor.

    void setup() {
    Serial.begin(115200);
    Serial.println("DHT11 test!");
    dht.begin();
}

  3. In the loop() function, read temperature and humidity values from the DHT11 sensor, and print them to the serial monitor.

    void loop() {
    // Wait a few seconds between measurements.
    delay(2000);

    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
    float humidity = dht.readHumidity();
    // Read temperature as Celsius (the default)
    float temperture = dht.readTemperature();

    // Check if any reads failed and exit early (to try again).
    if (isnan(humidity) || isnan(temperture)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
    }
    // Print the humidity and temperature
    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.print(" %\t");
    Serial.print("Temperature: ");
    Serial.print(temperture);
    Serial.println(" *C");
}

    • The dht.readHumidity() function is called to read the humidity value from the DHT sensor.

    • The dht.readTemperature() function is called to read the temperature value from the DHT sensor.

    • The isnan() function is used to check if the readings are valid. If either the humidity or temperature value is NaN (not a number), it indicates a failed reading from the sensor, and an error message is printed.

Phenomenon Picture

../_images/image243.jpeg