By Paul , 15 September 2025

ESP32 Weather Station Project

Overview

This project creates a complete weather station using an ESP32 microcontroller that reads temperature, humidity, and pressure data from sensors and displays the information on an OLED screen.

Components Required

Hardware

ESP32 Development Board (ESP32-WROOM-32 or similar)
BME280 Sensor Module (Temperature, Humidity, Pressure)
0.96" I2C OLED Display (SSD1306, 128x64 pixels)
Breadboard or PCB
Jumper Wires
Micro USB Cable
Optional: 3D printed enclosure

Software Libraries

Adafruit BME280 Library
Adafruit SSD1306 Library
Adafruit GFX Library
Wire Library (built-in)

Wiring Diagram

BME280 Connections

BME280    →    ESP32
VCC       →    3.3V
GND       →    GND
SCL       →    GPIO 22 (SCL)
SDA       →    GPIO 21 (SDA)

OLED Display Connections

OLED      →    ESP32
VCC       →    3.3V
GND       →    GND
SCL       →    GPIO 22 (SCL)
SDA       →    GPIO 21 (SDA)

Note: Both devices share the same I2C bus (SDA/SCL pins)

Arduino Code

#include <WiFi.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED Display Settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SCREEN_ADDRESS 0x3C

// Create objects
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
Adafruit_BME280 bme;

// WiFi credentials (optional - for future web features)
const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

// Sensor variables
float temperature;
float humidity;
float pressure;
float altitude;

// Display update interval
unsigned long lastUpdate = 0;
const unsigned long updateInterval = 2000; // Update every 2 seconds

void setup() {
  Serial.begin(115200);
  
  // Initialize I2C
  Wire.begin();
  
  // Initialize OLED Display
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  
  // Initialize BME280
  if (!bme.begin(0x76)) { // Try address 0x76 first
    if (!bme.begin(0x77)) { // If that fails, try 0x77
      Serial.println("Could not find a valid BME280 sensor, check wiring!");
      while (1);
    }
  }
  
  // Configure BME280 settings
  bme.setSampling(Adafruit_BME280::MODE_NORMAL,
                  Adafruit_BME280::SAMPLING_X2,  // temperature
                  Adafruit_BME280::SAMPLING_X2,  // pressure
                  Adafruit_BME280::SAMPLING_X2,  // humidity
                  Adafruit_BME280::FILTER_X16,
                  Adafruit_BME280::STANDBY_MS_500);
  
  // Clear display
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Weather Station");
  display.println("Initializing...");
  display.display();
  
  // Optional: Initialize WiFi
  initWiFi();
  
  delay(2000);
  
  Serial.println("Weather Station Ready!");
}

void loop() {
  if (millis() - lastUpdate >= updateInterval) {
    readSensors();
    updateDisplay();
    printToSerial();
    lastUpdate = millis();
  }
  
  // Add small delay to prevent watchdog timer issues
  delay(10);
}

void readSensors() {
  temperature = bme.readTemperature();
  humidity = bme.readHumidity();
  pressure = bme.readPressure() / 100.0F; // Convert Pa to hPa
  altitude = bme.readAltitude(1013.25); // Sea level pressure in hPa
}

void updateDisplay() {
  display.clearDisplay();
  
  // Title
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(25, 0);
  display.println("WEATHER STATION");
  
  // Draw separator line
  display.drawLine(0, 12, 128, 12, SSD1306_WHITE);
  
  // Temperature
  display.setCursor(0, 16);
  display.print("Temp: ");
  display.print(temperature, 1);
  display.print(" C");
  
  // Humidity
  display.setCursor(0, 28);
  display.print("Humid: ");
  display.print(humidity, 1);
  display.print(" %");
  
  // Pressure
  display.setCursor(0, 40);
  display.print("Press: ");
  display.print(pressure, 1);
  display.print(" hPa");
  
  // Altitude (optional)
  display.setCursor(0, 52);
  display.print("Alt: ");
  display.print(altitude, 0);
  display.print(" m");
  
  display.display();
}

void printToSerial() {
  Serial.println("=== Weather Station Reading ===");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.println(" %");
  
  Serial.print("Pressure: ");
  Serial.print(pressure);
  Serial.println(" hPa");
  
  Serial.print("Altitude: ");
  Serial.print(altitude);
  Serial.println(" m");
  
  Serial.println("==============================");
}

void initWiFi() {
  // Uncomment and configure if you want WiFi connectivity
  /*
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  
  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());
  */
}

// Function to handle sensor errors
void handleSensorError() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("SENSOR ERROR!");
  display.println("Check connections");
  display.display();
  
  Serial.println("Sensor reading error!");
  delay(1000);
}

Setup Instructions

1. Hardware Assembly

Connect the BME280 and OLED display to the ESP32 using the wiring diagram above
Both devices use I2C communication and share the same SDA/SCL pins
Ensure all connections are secure and use the correct voltage (3.3V)

2. Software Setup

Install the Arduino IDE
Add ESP32 board support:
- Go to File → Preferences
- Add https://dl.espressif.com/dl/package_esp32_index.json to Additional Board Manager URLs
- Go to Tools → Board → Boards Manager and install "esp32"
Install required libraries:
- Go to Sketch → Include Library → Manage Libraries
- Install: "Adafruit BME280 Library", "Adafruit SSD1306", "Adafruit GFX Library"
Upload the code:
- Select your ESP32 board (Tools → Board → ESP32 Dev Module)
- Select the correct COM port
- Upload the sketch

3. Testing

Open the Serial Monitor (115200 baud rate)
You should see sensor readings every 2 seconds
The OLED display should show current weather data

Features

Current Features

Real-time sensor readings every 2 seconds
OLED display showing temperature, humidity, pressure, and altitude
Serial monitor output for debugging
Error handling for sensor connectivity issues

Possible Enhancements

WiFi connectivity for web-based monitoring
Data logging to SD card or cloud
Weather forecasting based on pressure trends
Alerts for extreme weather conditions
Battery power with sleep modes for portable use
Web server to view data remotely
Historical data graphs
Multiple sensor locations (indoor/outdoor)

Troubleshooting

Common Issues

OLED not displaying: Check I2C address (try 0x3C or 0x3D)
BME280 not found: Check I2C address (try 0x76 or 0x77)
Jumbled display: Check power supply and connections
No sensor readings: Verify wiring and library installations

Verification Steps

Use I2C scanner code to detect device addresses
Check all solder joints and connections
Verify power supply voltage (should be 3.3V)
Test each component individually

Power Consumption

ESP32: ~80mA (active), ~5µA (deep sleep)
BMP180: ~5µA (standby), ~1000µA (measuring)
DHT11: ~0.5mA (standby), ~1.5mA (measuring)
OLED: ~20mA (on), ~0µA (off)

For battery operation, implement deep sleep between readings to extend battery life significantly. Note that DHT11 requires longer wake times due to its slower response.

Enclosure Ideas

3D printed weather-resistant case
Clear acrylic case for indoor use
Ventilated enclosure for accurate readings
Wall-mounted or desktop versions

This weather station provides a solid foundation for environmental monitoring and can be easily expanded with additional features!

Weather ESP32