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Arduino Weather Station guide

• Data 09/11/2025
• Autor Daniel Ionica
• 5
• 39

The DHT11 and DHT22 measure temperature and humidity. DHT22 offers higher accuracy and a wider range.

BMP180 / BME280

Measures pressure and temperature using the I2C interface.

LCD (16×2 I2C)

Displays data using the I2C interface — only two wires are required (SDA, SCL).
The most common I2C addresses are 0x27 or 0x3F.

Wiring Diagram

On Arduino Mega, use SDA = 20 and SCL = 21 instead.

Arduino Code Example

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP085.h>
#include <DHT.h>
#include <LiquidCrystal_I2C.h>

// Define sensors
#define DHTPIN 2
#define DHTTYPE DHT11   // or DHT22

DHT dht(DHTPIN, DHTTYPE);
Adafruit_BMP085 bmp;
LiquidCrystal_I2C lcd(0x27, 16, 2); // Change address if needed (0x3F or 0x27)

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.backlight();
  dht.begin();

  if (!bmp.begin()) {
    Serial.println("BMP180 not found!");
    lcd.print("BMP Error!");
    while (1);
  }

  lcd.clear();
  lcd.print("Weather Station");
  delay(2000);
}

void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  float p = bmp.readPressure() / 100.0; // hPa

  if (isnan(h) || isnan(t)) {
    Serial.println("DHT read error!");
    return;
  }

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("T:");
  lcd.print(t);
  lcd.print((char)223);
  lcd.print("C H:");
  lcd.print(h);
  lcd.print("%");

  lcd.setCursor(0, 1);
  lcd.print("P:");
  lcd.print(p);
  lcd.print(" hPa");

  Serial.print("Temp: "); Serial.print(t);
  Serial.print(" °C  Hum: "); Serial.print(h);
  Serial.print("%  Pressure: "); Serial.print(p);
  Serial.println(" hPa");

  delay(2000);
}

Explanation: This program reads data from the DHT and BMP sensors, then prints it to both the Serial Monitor and the LCD screen.

How It Works

1. The sensors measure temperature, humidity, and pressure.
2. Arduino reads and formats this data.
3. The LCD displays readings in real time.
4. Every few seconds, the data updates automatically.

Troubleshooting

Install these from Arduino IDE → Sketch → Include Library → Manage Libraries:

• DHT sensor library by Adafruit
• Adafruit Unified Sensor
• Adafruit BMP085 Library or Adafruit BME280
• LiquidCrystal_I2C

Optional: IoT Integration

Add an ESP8266 or ESP32 to send data to cloud platforms such as:

• ThingSpeak
• Blynk
• Adafruit IO

Use libraries like ESP8266WiFi.h and HTTPClient.h to upload readings as HTTP requests.

Expansion Ideas

• Add a rain sensor or anemometer (wind speed)
• Store data on an SD card
• Add a real-time clock (RTC) for timestamped data
• Display graphs on a web dashboard.