BMP180 Digital Barometer for Arduino

Specifications:

Supply voltage 1.62V - 3.6V.
I2C connection interface.
Accuracy up to 0.02hPa (17cm).
Range: 300hPa to 1100hPa (+ 9000m to -500m).

Wiring diagram

GND -> GND
VIN -> 3.3V
SDA -> A4
SCL -> A5

Sketch

#include 
#include 

BMP085 dps = BMP085 ();

long Temperature = 0, Pressure = 0;

void setup (void) {
 Serial.begin (9600);
 Wire.begin ();
 delay (1000);
 dps.init ();
}

void loop (void) {
 dps.getPressure (& Pressure);
 dps.getTemperature (& Temperature);

 Serial.print ("Pressure (mm Hg):");
 Serial.print (Pressure / 133.3); // Print the pressure in mmHg
 Serial.print ("Temp:");
 Serial.println (Temperature * 0.1); // Temperature in degrees Celsius
 delay (2000);
}

Cost: ~ 24