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Arduino Weather Station guide

• Data 09/11/2025
• Autor Daniel Ionica
• 6
• 446

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.

Arduino Distance Sensor with OLED Display

• Data 09/11/2025
• Autor Daniel Ionica
• 4
• 461

This project uses an HC-SR04 Ultrasonic Distance Sensor and a 0.96” I2C OLED display to measure and display the distance to an object in real-time.
It’s an excellent beginner-to-intermediate Arduino project that teaches sensor interfacing, I2C communication, and real-time data display.

In this guide, you’ll learn how to:

• Connect and use the HC-SR04 Ultrasonic Sensor
• Display the measured distance on an OLED screen
• Format readings for easy readability

Components Required

The HC-SR04 measures distance by sending out an ultrasonic pulse and timing how long it takes to bounce back.
The Arduino calculates the distance based on the time delay and the known speed of sound.

Distance Formula:

Distance (cm) = (Time in microseconds × 0.034) / 2

The division by 2 accounts for the round trip of the sound wave (out and back).

Pin Connections

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

Arduino Code Example


#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

delay(500);
}


Explanation: The Arduino sends a pulse from the HC-SR04 and measures the time it takes to return.
It then converts this time into distance and displays it on the OLED screen.

Code Breakdown

• pulseIn() measures the length of time the echo pin is HIGH.
• Distance is calculated using the speed of sound (0.034 cm/μs).
• Adafruit_SSD1306 and Adafruit_GFX libraries drive the OLED.
• Display refreshes every 0.5 seconds for updated readings.

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

• Adafruit SSD1306
• Adafruit GFX

Search for “Adafruit SSD1306” and “Adafruit GFX” and click Install.

Troubleshooting

Optional Upgrades

• Add a buzzer that activates when an object is too close.
• Display a bar graph or animation on the OLED.
• Send readings to the cloud using ESP8266 / ESP32.
• Log readings to an SD card.

Applications

• Parking assist system
• Object detection robot
• Smart trash bin (auto open lid)
• Liquid level detector.