BMP180 sensor and Arduino

   BMP180 sensor can give us information about pressure an temperature.

   This sensor is delivered on small module with 4 pins: Vin (+3.3V), GND, SDA and SCL.
   For testing, schematic is very simple:

   For control BMP180 sensor I use Adafruit-BMP085-Library, them test the example sketch.

   For a stand alone weather station with information about temperature and presure, I put a alphanumeric LCD display with 16 colons and 2 rows (1602):

and test montage is:

   I use this sketch:

// adapted sketch by niq_ro from http://nicuflorica.blogspot.ro/ & http://arduinotehniq.blogspot.com/
// https://github.com/adafruit/Adafruit-BMP085-Library
#include <Wire.h>
#include <Adafruit_BMP085.h>

/*************************************************** 
  This is an example for the BMP085 Barometric Pressure & Temp Sensor
  Designed specifically to work with the Adafruit BMP085 Breakout 
  ----> https://www.adafruit.com/products/391
  These displays use I2C to communicate, 2 pins are required to  
  interface
  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

// Connect VCC of the BMP085 sensor to 3.3V (NOT 5.0V!)
// Connect GND to Ground
// Connect SCL to i2c clock - on '168/'328 Arduino Uno/Duemilanove/etc thats Analog 5
// Connect SDA to i2c data - on '168/'328 Arduino Uno/Duemilanove/etc thats Analog 4
// EOC is not used, it signifies an end of conversion
// XCLR is a reset pin, also not used here

// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

/*                                    -------------------
                                      |  LCD  | Arduino |
                                      -------------------
 LCD RS pin to digital pin 7          |  RS   |   D7    |
 LCD Enable pin to digital pin 6      |  E    |   D6    |
 LCD D4 pin to digital pin 5          |  D4   |   D6    |
 LCD D5 pin to digital pin 4          |  D5   |   D4    |
 LCD D6 pin to digital pin 3          |  D6   |   D3    |
 LCD D7 pin to digital pin 2          |  D7   |   D2    |
 LCD R/W pin to ground                |  R/W  |   GND   |
                                      -------------------
*/



Adafruit_BMP085 bmp;
  
void setup() {
  lcd.begin(16, 2);
  // Print a logo message to the LCD.
  lcd.print("www.tehnic.go.ro");  
  lcd.setCursor(0, 1);
  lcd.print("creat de niq_ro");
  delay (2500);
  lcd.clear();

  // Print another message to the LCD.
  lcd.setCursor(2, 0);
  lcd.print("termometru -");  
  lcd.setCursor(0, 1);
  lcd.print("barometru ver1.0");
  delay (2500);
  lcd.clear();

  Serial.begin(9600);
  if (!bmp.begin()) {
 Serial.println("nu exita senzor compatibil BMP085 sau BMP180");
 while (1) {}
  }
}
  
void loop() {
    Serial.print("Temperatura = ");
    Serial.print(bmp.readTemperature());
    Serial.println(" *C");
    
    Serial.print("Presiune = ");
    Serial.print(bmp.readPressure());
    Serial.print(" Pa / ");
    
 //   Serial.print("Presiune = ");
    float presiune1 = bmp.readPressure()/101.325;
    presiune1 = presiune1 * 0.760;
    Serial.print(presiune1);
    Serial.println(" mmHg");
    
    
    // Calculate altitude assuming 'standard' barometric
    // pressure of 1013.25 millibar = 101325 Pascal
    Serial.print("Altitudine = ");
    Serial.print(bmp.readAltitude());
    Serial.println(" m");

    Serial.print("Presiune la nivelul marii (calculata) = ");
    Serial.print(bmp.readSealevelPressure());
    Serial.print(" Pa / ");
    
    // http://en.wikipedia.org/wiki/Atmospheric_pressure#Mean_sea_level_pressure
  //  Serial.print("Presiure la nivelul marii (calculata) = ");
    float presiune = bmp.readSealevelPressure()/101.325;
    presiune = presiune * 0.760;
    Serial.print(presiune);
    Serial.println(" mmHg");
    

  // you can get a more precise measurement of altitude
  // if you know the current sea level pressure which will
  // vary with weather and such. If it is 1015 millibars
  // that is equal to 101500 Pascals.
    Serial.print("Altitudine reala = ");
    Serial.print(bmp.readAltitude(101500));
    Serial.println(" m");
    
    Serial.println();
    
    
   lcd.setCursor(1, 0);
   lcd.print("temp.=  ");
    if ( bmp.readTemperature() < 10)
   {
     lcd.print(" "); 
     lcd.print(bmp.readTemperature());
   }
   else
   {
   lcd.print(bmp.readTemperature(),1);
   }
   lcd.write(0b11011111);
   lcd.print("C   ");
   
   lcd.setCursor(1, 1);
   lcd.print("pres.= p");
   lcd.print(presiune,0);
   lcd.print("mmHg  ");
    
   delay(2500);
}

24.11.2014
   In last weak-end, I received 3 pics from Dave (http://g4rvh.wordpress.com/) with a shield for Arduino Uno, made after my schematic:

   He made with board with CNC Cutter:

   I change the sketch for present the temperature in Fahrenheit, not in Celsius degree, using information from article http://www.mathsisfun.com/temperature-conversion.html: