Sensors: Pressure and temperature measurement with the BMP085 (GY-65 breakout board)

On the way to a small weather station we deal today with the air pressure and temperature measurement and use a breakout board for the BMP085 with an I²C interface, and an Arduino of our choice.

First, we wire up the breakout board with the Arduino (in this case an Arduino Nano clone) according to the following schedule (also seen in the picture above):

Wiring (Arduino and GY-65 breakout board):

Zoom level:

Move over elements (parts, jumper cable etc.) for more information (or tap in touch mode)...

Arduino (Pro Mini, Nano, Uno)	Arduino (Mega, Mega 2560)	GY-65 with BMP085
VCC 5V	VCC 5V	VCC
GND	GND	GND
A4 (SDA)	D20 (SDA)	SDA
A5 (SCL)	D21 (SCL)	SDL (SCL)

GY-65 breakout board (BMP085) – Pinout

Attention, there are several other breakout boards on the market that do not have an integrated voltage regulator, then they must be operated at 3.3 V.

Then we install the Adafruit BMP085 library from GitHub and upload the following sketch on our Arduino:

Source code (Sketch):

#include <Wire.h>
#include <Adafruit_BMP085.h>  // Adafruit BMP085 library

Adafruit_BMP085 bmp;

void setup(){

 // init serial monitor
 Serial.begin(9600);

 // Sensor init
 if (!bmp.begin()) {
  Serial.println("No valid BMP085 sensor found!");
  while (true) {}
 }
}

void loop(){

 Serial.print("Temperature: ");
 Serial.print(bmp.readTemperature());
 Serial.print(" ");  // Here we have to cheat a little
 Serial.write(176);  // to show the "°" character
 Serial.println("C");

 Serial.print("Humidity: ");
 Serial.print(bmp.readPressure());
 Serial.println(" Pa");

 Serial.print("Height: ");
 Serial.print(bmp.readAltitude());
 Serial.println(" meter");

 Serial.println(); 
 delay(5000);      // wait 5 seconds
}

… then we open the serial monitor and:

Sensoren: Luftdruck und Temperatur mit dem BMP085 - Serieller-Monitor