BME280/BMP280 - Barometric Pressure and Altitude

📊 BME280/BMP280 - Pressure, Altitude, and Weather Prediction

📊 What You'll Learn:

🌡️ Measure temperature, humidity, and barometric pressure
📈 Predict rain 12-24 hours in advance from pressure trends
🔌 Wire BME280/BMP280 using I2C (SDA/SCL pins)
💰 Choose BME280 ($10-15) or BMP280 ($5-8)

📊 Sensor Comparison

🌡️ BME280 ($10-15): Temperature + Humidity + Pressure → Complete weather station
📊 BMP280 ($5-8): Temperature + Pressure only → Budget option, no humidity

💡 Which to Choose?

BME280 is worth the extra $5 for humidity data - critical for disease prediction and crop stress monitoring. BMP280 is fine if you only need pressure for weather forecasting.

🔌 I2C Wiring (Both sensors same)

BME280/BMP280          ESP32
═══════════════        ════════
VCC            ─────►  3.3V
GND            ─────►  GND
SDA            ─────►  GPIO21
SCL            ─────►  GPIO22

I2C Address: 0x76 (SDO to GND) or 0x77 (SDO to 3.3V)

📖 Complete Code

#include <Wire.h>
#include <Adafruit_BME280.h>

Adafruit_BME280 bme;
float lastPressure = 0;

void setup() {
    Serial.begin(115200);
    Wire.begin();
    
    if (!bme.begin(0x76)) {
        Serial.println("❌ Sensor not found!");
        while(1);
    }
    Serial.println("✅ BME280 ready");
}

void loop() {
    float temp = bme.readTemperature();
    float hum = bme.readHumidity();
    float pressure = bme.readPressure() / 100.0F;
    float trend = pressure - lastPressure;
    
    Serial.println("━━━━━━━━━━━━━━━━━━━━━━━━");
    Serial.printf("🌡️ Temp: %.1f°C\n", temp);
    Serial.printf("💧 Humidity: %.0f%%\n", hum);
    Serial.printf("📊 Pressure: %.0f hPa\n", pressure);
    
    // Weather prediction
    if (trend > 2) {
        Serial.println("☀️ Rising pressure - Good weather coming");
    } else if (trend < -2) {
        Serial.println("🌧️ Falling pressure - Rain likely soon!");
    } else {
        Serial.println("➡️ Stable pressure - Conditions continue");
    }
    
    lastPressure = pressure;
    delay(60000);
}

💡 Weather Prediction Rules:

🌧️ Pressure drop > 2 hPa/hour: Rain likely in 12-24 hours

☀️ Pressure rise > 2 hPa/hour: Clearing weather

➡️ Stable pressure (±1 hPa): Current conditions continue

📉 Rapid drop > 4 hPa/hour: Storm approaching!

🎯 Key Takeaways:

✅ BME280 = Temp + Humidity + Pressure ($10-15)

✅ BMP280 = Temp + Pressure only ($5-8)

🔌 I2C pins: SDA→GPIO21, SCL→GPIO22

🌧️ Pressure drop = rain coming → reduce irrigation

💡 Key Takeaways:

Apply these concepts directly to your farm or project.

Take notes on important details for the quiz.

Use the button below to track your progress.

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