How to connect a BMP085 pressure sensor to Arduino

Contents

  1. Introduction
  2. Specification
  3. Wiring
  4. Code_Example
  5. References

Introduction

This is a simple breakout board for the BMP085 high-precision, low-power barometric pressure sensor. The BMP085 offers a measuring range of 300 to 1100 hPa with an absolute accuracy of down to 0.03 hPa. It's based on piezo-resistive technology for EMC robustness, high accuracy and linearity as well as long term stability. This sensor supports a voltage supply between 1.8 and 3.6VDC. It is designed to be connected directly to a micro-controller via the I²C bus This breadboard-friendly board breaks out all pins of the BMP085 to a 6-pin 0.1" pitch header. The analog and digital supplies (VDDD and VDDA) of the BMP085 are tied together into a single pin. We've also put two 4.7k pull-up resistors on the I2C lines.

Specification

  • Pressure sensing range: 300-1100 hPa (9000m to -500m above sea level)
  • Up to 0.03hPa / 0.25m resolution
  • -40 to +85°C operational range, +-2°C temperature accuracy
  • 2-pin i2c interface on chip
  • V1 of the breakout uses 3.3V power and logic level only
  • V2 of the breakout uses 3.3-5V power and logic level for more flexible usage
  • Digital two wire (I2C) interface
  • Wide barometric pressure range
  • Flexible supply voltage range
  • Ultra-low power consumption
  • Low noise measurement
  • Fully calibrated
  • Temperature measurement included
  • Ultra-flat, small footprint
  • 0.65 x 0.65" (16.5 x 16.5 mm)

bmp085 pressure sensor
Figure 1 - BMP085 Pressure Sensor

Wiring

You can see, there are 4 pins you have to use to connect the BMP085 pressure sensor to Arduino. Follow this guide:

Arduino Pin BMP085 Pin
A4 SDA
A5 SCL
3,3V VCC
Gnd GND
  • Connect GND to the ground pin.
  • Connect the SCL clock pin to Analog pin #5
  • Connect the SDA data pin to Analog pin #4
  • Connect the VCC pin to a 3.3V power source.

The V1 of the sensor breakout cannot be used with anything higher than 3.3V so don't use a 5V supply! V2 of the sensor board has a 3.3V regulator so you can connect it to either 3.3V or 5V if you do not have 3V available.

You don’t need to connect the XCLR (reset) or EOC (end-of-conversion) pins.


how to connect bmp085 pressure sensor to arudino uno
Figure 2 - How to connect BMP085 pressure sensor to Arudino UNO

Code Example

Download the following library and unzip it under the libraries directory of the Arduino IDE folder. For example, for my computer’s setup, the directory is: C:\Users\MyUserName\Documents\Arduino\libraries\ Create a folder for this example, then start the Arduino IDE. You will find the premade library in the file-> examples menu. Open it then run the example.

Download: BMP085 Arduino Library.zip

If you wish to exploit more information eg. temperatue, altitude from your sensor just update the void loop() function in the following way: 

void loop(void)
{
  sensors_event_t event;
  bmp.getEvent(&event);
 
  if (event.pressure)
  {
    Serial.print("Pressure:    ");
    Serial.print(event.pressure);
    Serial.println(" hPa");
    
    float temperature;
    bmp.getTemperature(&temperature);
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" C");

    float seaLevelPressure = SENSORS_PRESSURE_SEALEVELHPA;
    Serial.print("Altitude:    "); 
    Serial.print(bmp.pressureToAltitude(seaLevelPressure,
    event.pressure,
    temperature)); 
    Serial.println(" m");
    Serial.println("");
  } 
  else
  {
    Serial.println("Sensor error");
  }
  delay(1000);
}

References

More information