BMP180 Barometric Pressure Sensor Tutorial

1. Introduction

The BMP180 is a digital barometric pressure sensor by Bosch for altitude measurement and weather monitoring. It measures atmospheric pressure (which decreases with elevation) and includes a temperature sensor for compensated readings.

📦 Key Features

Pressure range: 300-1100 hPa
Can detect altitude changes as small as 25cm
Built-in temperature sensor
Ultra-low power consumption

2. Technical Specifications

Parameter	Specification
Operating Voltage	1.8V – 3.6V (module: 3.3V – 5V)
Interface	I2C (address: 0x77 fixed)
Pressure Range	300 – 1100 hPa
Pressure Accuracy	±0.12 hPa
Temperature Range	-40°C to +85°C
Temperature Accuracy	±1.0°C
Current Consumption	5 µA @ 1 sample/sec

💡 Altitude Formula

Altitude = 44330 × (1 - (P / P₀)^0.1903)

Where P = measured pressure, P₀ = sea level pressure (1013.25 hPa)

3. Wiring Guide

BMP180 Pin	ESP32	Arduino Uno
VCC	3.3V	3.3V
GND	GND	GND
SCL	GPIO 22	A5
SDA	GPIO 21	A4

Figure 1: BMP180 I2C wiring with ESP32

4. Project: Altitude & Weather Monitor

Required Library

Install Adafruit BMP085 Library via Arduino Library Manager.

Complete Code

#include <Wire.h>
#include <Adafruit_BMP085.h>

#define SEALEVEL_PRESSURE 101325  // Adjust for your location

Adafruit_BMP085 bmp;

void setup() {
    Serial.begin(115200);
    Serial.println("BMP180 Altitude Monitor");
    
    if (!bmp.begin()) {
        Serial.println("ERROR: BMP180 not found!");
        while (1);
    }
    Serial.println("BMP180 Ready!");
}

void loop() {
    float temp = bmp.readTemperature();
    float pressure = bmp.readPressure();
    float altitude = bmp.readAltitude(SEALEVEL_PRESSURE);

    Serial.println("------------------------");
    Serial.print("Temperature: "); Serial.print(temp); Serial.println(" C");
    Serial.print("Pressure: "); Serial.print(pressure/100); Serial.println(" hPa");
    Serial.print("Altitude: "); Serial.print(altitude); Serial.println(" m");

    // Weather forecast
    float hPa = pressure / 100.0;
    if (hPa > 1022) Serial.println("Forecast: Clear skies");
    else if (hPa > 1013) Serial.println("Forecast: Fair");
    else if (hPa > 1000) Serial.println("Forecast: Cloudy");
    else Serial.println("Forecast: Stormy");

    delay(3000);
}

5. Troubleshooting

BMP180 not found

Check wiring connections
Run I2C scanner - should find 0x77

Wrong altitude readings

Calibrate SEALEVEL_PRESSURE for your location
Get current pressure from local weather service

6. Summary

Measures pressure (300-1100 hPa) and temperature
Altitude resolution: ~25cm
Fixed I2C address: 0x77
Use Adafruit_BMP085 library