Meteorology IoT Barometric Pressure Lux Meter

Automated Multi-Sensor Mini Weather Station with LCD Forecast

Integrate barometric atmospheric pressure (BMP280), ambient humidity (DHT11), and solar irradiance (LDR) sensors with an Arduino Uno to compute live barometric altitude and forecast weather changes.

Reading Time 11 Minutes

Difficulty Level Intermediate

Hardware Platform Arduino Uno, BMP280, LDR

1. Aim of the Project

Project Objective

The aim is to build a compact meteorological weather station that measures barometric pressure (hPa), temperature (°C), relative humidity (%), and sunlight levels, calculating altitude above sea level and predicting short-term atmospheric weather fronts based on barometric pressure trends.

2. Interactive 3D Assembly & Circuit Wiring Model

Rotate the 3D model 360 degrees, zoom in/out, disassemble/explode parts to inspect individual hardware layers, toggle realistic circuit wires, and click any component to inspect its engineering specifications.

Left Click + Drag: Rotate Orbit (360°)

Right Click + Drag: Pan Scene

Scroll: Zoom In / Out

Click Component: Inspect Hardware Details

Hovered Component

3. Laboratory Video Masterclass Tutorial

Step-by-step video walkthrough covering breadboard circuit assembly, wiring verification, and testing. Enrolled students and instructors can access video streaming below.

2. Learning Outcomes

Barometric Hypsometric Equation

Learn how air pressure drops predictably with altitude (approx. 1 hPa per 8.5 meters) and calculate elevation.

Photoresistor Light Transduction

Convert photon flux into variable analog voltages using cadmium sulfide (CdS) photoresistive cells.

3. Required Components

Component Name	Quantity	Specification	Interface
Arduino Uno	1	Central Controller	USB / 5V
BMP280 Barometric Sensor	1	Digital Pressure (300-1100 hPa) & Temp	I2C (A4, A5)
LDR Photoresistor & 10k Resistor	1	Sunlight Intensity Sensor	Analog Pin A0
16x2 I2C LCD Display	1	Display for Weather Telemetry	I2C (A4, A5)

4. Circuit Connections

Sensor Pin	Arduino Pin	Function
BMP280 SDA / SCL	Pins A4, A5	I2C Bus
LDR Divider Out	Pin A0	Analog Light Intensity

5. Complete Arduino Source Code

mini_weather_station.ino

/*
 * Project: Automated Multi-Sensor Mini Weather Station
 * Author: ElectronLab STEM Curriculum
 */

#include <Wire.h>
#include <Adafruit_BMP280.h>
#include <LiquidCrystal_I2C.h>

Adafruit_BMP280 bmp;
LiquidCrystal_I2C lcd(0x27, 16, 2);

const int LDR_PIN = A0;

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  
  if (!bmp.begin(0x76)) { // Try 0x76 or 0x77
    Serial.println("Could not find a valid BMP280 sensor!");
    lcd.print("BMP280 Err 0x76");
    while (1);
  }
}

void loop() {
  float tempC = bmp.readTemperature();
  float pressureHpa = bmp.readPressure() / 100.0F;
  float altitudeM = bmp.readAltitude(1013.25); // Standard sea level pressure
  int lightRaw = analogRead(LDR_PIN);
  int lightPercent = map(lightRaw, 0, 1023, 0, 100);

  // Display Screen 1: Temp & Pressure
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(tempC, 1);
  lcd.print((char)223);
  lcd.print("C");

  lcd.setCursor(0, 1);
  lcd.print("Pres: ");
  lcd.print(pressureHpa, 1);
  lcd.print(" hPa");
  delay(3000);

  // Display Screen 2: Altitude & Sunlight
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Alt: ");
  lcd.print(altitudeM, 1);
  lcd.print(" m");

  lcd.setCursor(0, 1);
  lcd.print("Sunlight: ");
  lcd.print(lightPercent);
  lcd.print("%");
  delay(3000);
}

6. Working Principle

The BMP280 utilizes piezo-resistive micro-electromechanical (MEMS) pressure diaphragm cells to measure air density with 0.16 Pa precision. Falling barometric pressure indicates incoming low-pressure storm systems, while rising pressure signals clear sunny conditions.

7. Troubleshooting Guide

BMP280 Sensor Not Found

BMP280 modules commonly have either I2C address 0x76 (SDO pin to GND) or 0x77 (SDO pin to 3.3V). Specify bmp.begin(0x76) in your setup.