Creating a Temperature-Controlled Fan System with Arduino Nano, LCD, DHT11, Buzzer, and Fan

Title: Creating a Temperature-Controlled Fan System with Arduino Nano, LCD, DHT11, Buzzer, and Fan

In this project, we will build a temperature-controlled fan system using an Arduino Nano, an LCD display, a DHT11 sensor, a fan, and a buzzer. The system monitors the temperature and automatically triggers the fan when the temperature crosses a certain threshold. The current temperature and humidity levels will be displayed on the LCD, and an alarm will sound if it gets too hot.

 

 

Components Required:

  • Arduino Nano
  • DHT11 Temperature and Humidity Sensor
  • 16×2 LCD (with I2C interface)
  • Fan (DC motor or small cooling fan)
  • Buzzer
  • NPN Transistor (for driving the fan)
  • Diode (for back EMF protection)
  • Resistors
  • Breadboard and jumper wires

Circuit Diagram:

  1. DHT11 Sensor:
    • VCC: Connect to 5V on Arduino Nano
    • GND: Connect to GND on Arduino Nano
    • Data Pin: Connect to Digital Pin D12 on Arduino Nano

  2. 16×2 LCD  Pin Connections:

    1. RS (Register Select): Connect to digital pin 7 on Arduino Nano.
    2. E (Enable): Connect to digital pin 6 on Arduino Nano.
    3. D4: Connect to digital pin 5 on Arduino Nano.
    4. D5: Connect to digital pin 4 on Arduino Nano.
    5. D6: Connect to digital pin 3 on Arduino Nano.
    6. D7: Connect to digital pin 2 on Arduino Nano.
    7. VSS: Connect to GND on Arduino Nano.
    8. VDD: Connect to 5V on Arduino Nano.
    9. RW (Read/Write): Connect to GND (for write mode).
    10. K (LED Cathode): Connect to GND (for backlight).
    11. A (LED Anode): Connect to 5V (for backlight).
    12. V0: Connect to the middle pin of a 10kΩ potentiometer (adjust for contrast).

    Fan:

    • Connect the fan to the collector of the NPN transistor.
    • Emitter of the transistor goes to GND.
    • The base is connected to a resistor, which is connected to a digital pin (D9) of Arduino.
    • A diode is connected across the fan to protect from back EMF.
  3. Buzzer:
    • Positive pin of the buzzer to D8
    • Negative pin to GND

Code Implementation

You need to use the LiquidCrystal library for directly controlling the LCD .

////////////////////////////////////////

#include <Wire.h>
#include <LiquidCrystal.h>
#include <DHT.h>

#define DHTPIN 12 // Pin where the DHT11 is connected
#define DHTTYPE DHT11
#define FAN_PIN 9 // Fan connected to Pin 9
#define BUZZER_PIN 8 // Buzzer connected to Pin 8

DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

void setup() {
pinMode(FAN_PIN, OUTPUT);
pinMode(BUZZER_PIN, OUTPUT);
lcd.begin();

dht.begin();
Serial.begin(9600);
}

void loop() {
float h = dht.readHumidity();
float t = dht.readTemperature();

if (isnan(h) || isnan(t)) {
lcd.clear();
lcd.setCursor(0, 0);
lcd.print(“Sensor Error”);
return;
}

lcd.clear();
lcd.setCursor(0, 0);
lcd.print(“Temp: “);
lcd.print(t);
lcd.print(” C”);

lcd.setCursor(0, 1);
lcd.print(“Humidity: “);
lcd.print(h);
lcd.print(” %”);

// Control fan based on temperature threshold
if (t > 30) { // if temp exceeds 30°C, fan turns on
digitalWrite(FAN_PIN, HIGH);
digitalWrite(BUZZER_PIN, HIGH); // Activate buzzer for high temperature
} else {
digitalWrite(FAN_PIN, LOW);
digitalWrite(BUZZER_PIN, LOW);
}

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

/////////////////////////////

Explanation:

  1. Libraries Used:
    • <LiquidCrystal.h>: Handles the 16×2 LCD .
    • DHT: Reads temperature and humidity values from the DHT11 sensor.
  2. Temperature Monitoring:
    • The DHT11 sensor reads the temperature and humidity every 2 seconds.
    • The LCD displays the current temperature and humidity in real-time.
  3. Fan and Buzzer Control:
    • The fan is connected to a transistor, allowing it to be powered by the Arduino when the temperature exceeds 30°C.
    • The buzzer activates simultaneously to alert when the temperature is too high, providing an auditory warning.
  4. Fan Activation Logic:
    • If the temperature exceeds the set threshold (30°C), the fan and buzzer are activated to cool down the system and provide an alert.
    • Once the temperature drops below 30°C, both the fan and buzzer turn off.

Final Result:

 

 

As shown in the image and video, the system successfully monitors the temperature and controls the fan accordingly. The fan is activated automatically when the temperature exceeds a defined threshold, and the buzzer sounds an alert. The LCD continuously displays the temperature and humidity values, providing a visual representation of the environment.

Applications:

  • Home automation cooling systems
  • Temperature regulation in closed spaces
  • Smart ventilation systems

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