Weather Station Using I2C

Simple Weather Station Using I2C

Difficulty Level: Intermediate

In this project, we will build a simple weather station using I2C sensors to measure temperature, humidity, and pressure. The data will be displayed on an I2C LCD, making it easy to monitor environmental conditions in real time. This project is ideal for enthusiasts looking to explore IoT and environmental monitoring.

Components Required

• 1 x Arduino (any model)
• 1 x DHT22 Temperature & Humidity Sensor
• 1 x BMP280 Pressure Sensor (I2C)
• 1 x 16x2 I2C LCD Display
• Jumper Wires
• Breadboard

Wiring Diagram

Follow these connections to build the circuit:

• DHT22 Temperature & Humidity Sensor:
• VCC to 5V on Arduino
• GND to GND on Arduino
• Data pin to digital pin 2 on Arduino
• BMP280 Pressure Sensor: (I2C Interface)
• SCL to A5 (SCL on Arduino)
• SDA to A4 (SDA on Arduino)
• VCC to 3.3V on Arduino
• GND to GND on Arduino
• 16x2 I2C LCD Display:
• SCL to A5 (SCL on Arduino)
• SDA to A4 (SDA on Arduino)
• VCC to 5V on Arduino
• GND to GND on Arduino

Code Explanation

We will use three libraries for this project:

• Adafruit_BMP280 for reading the pressure sensor
• DHT for reading temperature and humidity from the DHT22 sensor
• LiquidCrystal_I2C for controlling the 16x2 I2C LCD

The sensors will send data to the Arduino via I2C, and the Arduino will then display the temperature, humidity, and pressure on the LCD.

Arduino Code

Below is the Arduino code for the weather station:

#include 
#include 
#include 
#include 
#include 

// Define pin for DHT sensor and type
#define DHTPIN 2
#define DHTTYPE DHT22

// Initialize DHT sensor
DHT dht(DHTPIN, DHTTYPE);

// Initialize BMP280 sensor
Adafruit_BMP280 bmp;

// Initialize I2C LCD (address 0x27)
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);
  dht.begin();  // Start DHT sensor
  bmp.begin();  // Start BMP280 sensor
  lcd.begin();  // Start I2C LCD
  lcd.backlight();  // Turn on backlight
  lcd.setCursor(0, 0);
  lcd.print("Weather Station");
}

void loop() {
  delay(2000);  // Wait for sensor readings

  // Read temperature and humidity from DHT22
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  
  // Read pressure from BMP280
  float pressure = bmp.readPressure() / 100.0F;  // Convert Pa to hPa
  
  // Check if readings are valid
  if (isnan(temp) || isnan(hum)) {
    lcd.setCursor(0, 1);
    lcd.print("Error reading DHT");
    return;
  }

  // Display the readings on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temp);
  lcd.print(" C");

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

  lcd.setCursor(0, 1);
  lcd.print("Pressure: ");
  lcd.print(pressure);
  lcd.print(" hPa");

  // Also print data to serial monitor
  Serial.print("Temperature: ");
  Serial.print(temp);
  Serial.println(" C");
  
  Serial.print("Humidity: ");
  Serial.print(hum);
  Serial.println(" %");

  Serial.print("Pressure: ");
  Serial.print(pressure);
  Serial.println(" hPa");
}
        

Upload and Test

1. Connect your Arduino to the computer and upload the code.
2. Open the Serial Monitor to verify the sensor readings.
3. Observe the temperature, humidity, and pressure values displayed on the LCD screen.

Conclusion

This weather station demonstrates the use of I2C communication for reading sensor data and displaying it on an I2C LCD. You can further expand the project by adding other environmental sensors, logging the data to an SD card, or transmitting it to the internet for remote monitoring.