Barometer on an Arduino Uno

// Barometer: a BMP180 read with the Adafruit BMP085 library, which drives the
// BMP180 too: temperature, pressure and altitude.
//
//   BMP180 (GY-68)   SDA -> A4   SCL -> A5   VCC -> 5 V   GND -> GND
//
// The sensor does not hand over degrees and pascals. It gives raw counts and
// eleven calibration words, and the library runs the datasheet's integer
// arithmetic to turn them into a temperature to a tenth of a degree and a
// pressure to a pascal. The altitude is the barometric formula against
// standard sea-level pressure, 101325 Pa, so it is only right on a day when
// the sea-level pressure is standard: weather moves it by tens of meters.
//
// Drag the two sliders on the breakout.

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

Adafruit_BMP085 bmp;

void setup() {
  Serial.begin(9600);
  if (!bmp.begin()) {
    Serial.println("Could not find a valid BMP085 sensor, check wiring!");
    while (1) {
    }
  }
  Serial.println("Barometer ready");
}

void loop() {
  Serial.print("Temperature = ");
  Serial.print(bmp.readTemperature(), 1);
  Serial.print(" *C  Pressure = ");
  Serial.print(bmp.readPressure());
  Serial.print(" Pa  Altitude = ");
  Serial.print(bmp.readAltitude(), 0);
  Serial.println(" meters");
  delay(500);
}