Build Your Own Smart Temperature & Humidity Monitor with Arduino and DHT11
Temperature and Humidity Monitor with DHT11 and LCD Circuit Diagram

Build Your Own Smart Temperature & Humidity Monitor with Arduino and DHT11

Monitoring environmental conditions, specifically temperature and humidity is crucial in various scenarios. In this Arduino-based project, we will delve into creating a smart temperature and humidity monitor using the DHT11 sensor and Arduino.

Components Required  for the Temperature and Humidity Monitor with DHT11

  • Arduino Uno
  • DHT11 temperature and humidity sensor
  • LCD 16×2
  • Breadboard Jumper wires
  • USB cable type A/B

Software

Arduino IDE

DH11

The heartbeat of our project lies in the DHT11 sensor. Known for its accuracy and simplicity, the DHT11 plays a crucial role in measuring ambient temperature and humidity. Understanding its capabilities is key to a successful project.

The DHT11 is a sensor that measures temperature and humidity. It uses a humidity sensor and a thermistor to detect moisture and temperature changes, providing digital output in a specific communication protocol. While affordable, it has some accuracy limitations compared to more advanced sensors.

Supply Voltage3.5V to 5.5V
Current Consumption2.5mA (max)
Humidity Range20% to 90% RH
Temperature Range0°C to 50°C
Temperature Accuracy±2°C
Humidity Accuracy±5% RH
Resolution1°C (temperature)
Communication ProtocolDigital
Sampling Period1 Hz
Dimensions15.5mm x 12mm
Communication ProtocolSingle-wire digital interface
Measurement Time2 seconds (typical)

The Data Format of the DHT11 Module

Data Format:

  • Integral Relative Humidity (RH): 8 bits
  • Decimal Relative Humidity (RH): 8 bits
  • Integral Temperature (T): 8 bits
  • Decimal Temperature (T): 8 bits
  • Checksum: 8 bits

Example: Suppose the DHT11 module sends the following data:

RH = 25.50% (25in integral part, 50 in decimal part) T = 22.75°C (22 in integral part, 75 in decimal part)

The complete 40-bit data sequence would be:

  • Integral RH: 25 (binary: 00110001)
  • Decimal RH: 50 (binary: 00110010)
  • Integral T: 22 (binary: 00010110)
  • Decimal T: 75 (binary: 01001011)
  • Checksum: 170 (binary: 10101010)

Transmission Order: 00011001 00110010 00010110 01001011 10101010

  1. Initialization: The Arduino sends a start signal to the DHT11.
  2. Response: The DHT11 sends the 40-bit data stream.
  3. Parsing: The Arduino code separates the bits into RH, T, and checksum values.
  4. Verification: The checksum is calculated and compared to the received checksum to ensure data integrity.
  5. Processing: The valid RH and T values are used for further calculations or display in the Arduino code.

Temperature and Humidity Monitor with DHT11 Circuit Diagram

Follow the detailed circuit diagram provided to assemble the components correctly. The visual representation ensures a seamless setup process.

Temperature and Humidity Monitor with DHT11 Circuit Diagram
Temperature and Humidity Monitor with DHT11 Circuit Diagram

Libraries for the DHT11 Project

You have to install the DHT sensor library by Adafruit to run the code. To install the Adafruit DHT sensor library in the Arduino IDE, click on “Sketch” > “Include Library” > “Manage Libraries” search for “DHT sensor library” or “Adafruit DHT sensor library”, and click “Install All.”.

Arduino Temperature and Humidity Monitor with DHT11 Code

Dive into the details of the Arduino Temperature and Humidity Monitor with DHT11 as the code unfolds, showcasing how accurate programming turns the project into a dependable and user-friendly system.

/******** www.arduinopoint.com *****************************/
/******** Arduino Temperature and Humidity Monitor with DHT11 ***********/
#include <DHT.h>
#define DHTPIN 8   // Define the pin to which the DHT11 sensor is connected: Here Digital Pin 8
#define DHTTYPE DHT11   // Define the type of DHT sensor
DHT dht(DHTPIN, DHTTYPE);  // Create a DHT object

void setup() {
  Serial.begin(9600);   // Start serial communication
  dht.begin();          // Initialize the DHT sensor
}

void loop() {
  delay(2000);  // Delay for 2 seconds (adjust as needed)
  // Read temperature and humidity from the DHT sensor
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  // Check if the readings are valid
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Display the temperature and humidity readings on the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print(" °C | Humidity: ");
  Serial.print(humidity);
  Serial.println(" %");
}

To find the Temperature and humidity output in the Arduino IDE Serial Monitor, open the Arduino IDE, upload the code to your Arduino board, and then click on the magnifying glass icon or navigate to “Tools” > “Serial Monitor” to view the real-time data.

Serial Monitor Output of Temperature and Humidity Monitor with DHT11
Serial Monitor Output of Temperature and Humidity Monitor with DHT11

Temperature and Humidity Monitor with DHT11 and LCD Circuit Diagram

Temperature and Humidity Monitor with DHT11 and LCD Circuit Diagram
Temperature and Humidity Monitor with DHT11 and LCD Circuit Diagram

An Arduino is connected to a liquid crystal display (LCD) that shows temperature and humidity using a 4-bit mode connection. The LCD’s pins (RS, EN, D4, D5, D6, D7) link to digital pins 2, 3, 4, 5, 6, and 7 on the Arduino. Additionally, a DHT11 sensor module is connected to digital pin 8 on the Arduino. Also, a potentiometer is used to adjust the contrast of the LCD.

Arduino Temperature and Humidity Monitor with DHT11 and LCD Code

Discover the Arduino Temperature and Humidity Monitor with DHT11 and LCD 16×2 through straightforward code, highlighting how precision in programming makes it easy to use.

/******** www.arduinopoint.com *****************************/
/******** Arduino Temperature and Humidity Monitor with DHT11 and LCD ***********/
#include <DHT.h>
#include <LiquidCrystal.h>

#define DHTPIN 8  // Define the pin to which DHT11 is connected
#define DHTTYPE DHT11  // Define the type of DHT sensor

DHT dht(DHTPIN, DHTTYPE);  // Initialize DHT sensor
//
LiquidCrystal lcd(4, 5, 6, 7, 2, 3); // Initialize LCD; LCD's D4, D5, D6, D7, RS, and E pins are connected, respectively.

void setup() {
  lcd.begin(16, 2);  // Initialize the LCD columns and rows
  Serial.begin(9600);  // Initialize serial communication

  lcd.print("Temp:");  // Display "Temp:" on LCD
  lcd.setCursor(0, 1);  // Move cursor to the second row
  lcd.print("Humidity:");  // Display "Humidity:" on LCD
}

void loop() {
  float temperature = dht.readTemperature();  // Read temperature from DHT sensor
  float humidity = dht.readHumidity();  // Read humidity from DHT sensor

  lcd.setCursor(6, 0);  // Move cursor to temperature position on LCD
  lcd.print(temperature);  // Display temperature on LCD
  lcd.print(" ");  // Print a space for formatting
  lcd.write(223);  // Display the degree symbol
  lcd.print("C");  // Display Celsius on LCD

  lcd.setCursor(9, 1);  // Move cursor to humidity position on LCD
  lcd.print(humidity);  // Display humidity on LCD
  lcd.print("%");  // Display percentage symbol on LCD

  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print("°C, Humidity: ");
  Serial.print(humidity);
  Serial.println("%");

  delay(2000);  // Delay for 2 seconds before the next reading
}

Caution

Loose or faulty wires can hinder project success. The caution section highlights the importance of thorough wire checks before initiating any project.

Applications of the Smart Monitor

Explore practical uses for the temperature and humidity monitor, from home applications to industrial settings. Adapt the project to suit various environments.

Future Enhancements

Encourage readers to experiment with and modify the project for personalized enhancements. Sharing ideas for future improvements fosters creativity.

Conclusion

In conclusion, this DIY project offers an insightful journey into creating a smart temperature and humidity monitor. Recap the key takeaways and inspire readers to embark on their own DIY adventure.

FAQs

  1. Is the DHT11 sensor suitable for outdoor use?

    • Answer: The DHT11 sensor is designed for indoor use. For outdoor applications, consider weather-resistant alternatives.
  2. Can I use a different Arduino board for this project?

    • Answer: While the tutorial focuses on Arduino Uno, other boards with similar capabilities can be used with minor adjustments to the code.
  3. What is the range of the temperature and humidity measurements?

    • Answer: The DHT11 sensor typically measures temperatures from 0 to 50°C and humidity from 20% to 90%.
  4. How often should I calibrate the monitor?

    • Answer: Periodic calibration is recommended, especially if environmental conditions change significantly. Follow the provided guidelines for calibration.
  5. Can I add additional sensors to the project?

    • Answer: Yes, you can expand the project by incorporating more sensors. Adjust the code accordingly to accommodate additional data.

Additional Tips

For optimal performance, keep the project in a controlled environment. Avoid exposing the DHT11 to extreme conditions, ensuring prolonged sensor life.

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