Hey i am also new here,
may be some one are interested in a due working sketch for the BMP085
/***********************************************************************************************
* Sketch: BMP085_Text.ino
* Author: A. Kriwanek: http://www.kriwanek.de/arduino/wetterstation.html
* Version: 1.00 01.09.2012/17:15
*
* This sketch tests a BMP085 barometric sensor. Temperature and pressure are read from the sensor
* The mathematical computation is done and the results will be displayed every second on the
* serial monitor.
*
* Used Hardware:
* - Sparkfun Breakout board BMP085
* - Arduino UNO Protoboard
* - Arduino UNO
*
* My sketch is free software: Arduino BMP085_Text.ino von Andreas Kriwanek steht unter
* einer Creative Commons Namensnennung-Weitergabe unter gleichen Bedingungen 3.0 Unported Lizenz.
*
* My Sketch in wide parts is based on the sketch from Jim Lindblom:
*
* BMP085 Extended Example Code
* by: Jim Lindblom
* SparkFun Electronics
* date: 1/18/11
* license: CC BY-SA v3.0 - http://creativecommons.org/licenses/by-sa/3.0/
*
* Update (7/19/11): I've heard folks may be encountering issues
* with this code, who're running an Arduino at 8MHz. If you're
* using an Arduino Pro 3.3V/8MHz, or the like, you may need to
* increase some of the delays in the bmp085ReadUP and
* bmp085ReadUT functions.
*
* https://www.sparkfun.com/products/9694 Product page
* http://de.wikipedia.org/wiki/Luftdruck Correction formula to sea level
* http://www.meteo24.de/wetter/49X8157.html Weather Bad Aibling
*
**********************************************************************************************/
#include <Wire.h>
#define BMP085_ADDRESS 0x77 // I2C address of BMP085
const unsigned char OSS = 0; // Oversampling Setting
// Calibration values of BMP085:
short ac1;
short ac2;
short ac3;
unsigned short ac4;
unsigned short ac5;
unsigned short ac6;
short b1;
short b2;
short mb;
short mc;
short md;
// b5 is calculated in bmp085GetTemperature(...), this variable is also used in bmp085GetPressure(...)
// so ...Temperature(...) must be called before ...Pressure(...).
long b5;
float temperature;
float pressure;
float pressureNN;
float pressureCorrection = 0.98731518; // Höhe 103 ü.NN Halle. Please calculate your coeffizient
// for your homes elevation!
//----------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------
void setup()
{
Serial.begin(115200);
Wire.begin();
bmp085Calibration();
}
//----------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------
void loop()
{
temperature = bmp085GetTemperature(bmp085ReadUT())/10;
pressure = bmp085GetPressure(bmp085ReadUP())/100;
pressureNN = pressure / pressureCorrection;
Serial.print("Temperature: ");
Serial.print(temperature,1);
Serial.print(" C, Pressure: ");
Serial.print(pressure,1);
Serial.print(" hPa in 103m height above sea level, Pressure-NN: ");
Serial.print(pressureNN,1);
Serial.println(" hPa");
delay(1000);
}
//----------------------------------------------------------------------------------------------------------
// Stores all of the bmp085's calibration values into global variables
// Calibration values are required to calculate temp and pressure
// This function should be called at the beginning of the program
void bmp085Calibration()
{
ac1 = bmp085ReadInt(0xAA);
ac2 = bmp085ReadInt(0xAC);
ac3 = bmp085ReadInt(0xAE);
ac4 = bmp085ReadInt(0xB0);
ac5 = bmp085ReadInt(0xB2);
ac6 = bmp085ReadInt(0xB4);
b1 = bmp085ReadInt(0xB6);
b2 = bmp085ReadInt(0xB8);
mb = bmp085ReadInt(0xBA);
mc = bmp085ReadInt(0xBC);
md = bmp085ReadInt(0xBE);
}
//----------------------------------------------------------------------------------------------------------
// Calculate temperature given ut.
// Value returned will be in units of 0.1 deg C
short bmp085GetTemperature(unsigned short ut)
{
long x1, x2;
x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
x2 = ((long)mc << 11)/(x1 + md);
b5 = x1 + x2;
return ((b5 + 8)>>4);
}
//----------------------------------------------------------------------------------------------------------
// Calculate pressure given up
// calibration values must be known
// b5 is also required so bmp085GetTemperature(...) must be called first.
// Value returned will be pressure in units of Pa.
long bmp085GetPressure(unsigned long up)
{
long x1, x2, x3, b3, b6, p;
unsigned long b4, b7;
b6 = b5 - 4000;
// Calculate B3
x1 = (b2 * (b6 * b6)>>12)>>11;
x2 = (ac2 * b6)>>11;
x3 = x1 + x2;
b3 = (((((long)ac1)*4 + x3)<<OSS) + 2)>>2;
// Calculate B4
x1 = (ac3 * b6)>>13;
x2 = (b1 * ((b6 * b6)>>12))>>16;
x3 = ((x1 + x2) + 2)>>2;
b4 = (ac4 * (unsigned long)(x3 + 32768))>>15;
b7 = ((unsigned long)(up - b3) * (50000>>OSS));
if (b7 < 0x80000000)
p = (b7<<1)/b4;
else
p = (b7/b4)<<1;
x1 = (p>>8) * (p>>8);
x1 = (x1 * 3038)>>16;
x2 = (-7357 * p)>>16;
p += (x1 + x2 + 3791)>>4;
return p;
}
//----------------------------------------------------------------------------------------------------------
// Read 1 byte from the BMP085 at 'address'
char bmp085Read(unsigned char address)
{
unsigned char data;
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 1);
while(!Wire.available())
;
return Wire.read();
}
//----------------------------------------------------------------------------------------------------------
// Read 2 bytes from the BMP085
// First byte will be from 'address'
// Second byte will be from 'address'+1
short bmp085ReadInt(unsigned char address)
{
unsigned char msb, lsb;
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 2);
while(Wire.available()<2)
;
msb = Wire.read();
lsb = Wire.read();
return (short) msb<<8 | lsb;
}
//----------------------------------------------------------------------------------------------------------
// Read the uncompensated temperature value
unsigned short bmp085ReadUT()
{
unsigned short ut;
// Write 0x2E into Register 0xF4
// This requests a temperature reading
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF4);
Wire.write(0x2E);
Wire.endTransmission();
// Wait at least 4.5ms
delay(5);
// Read two bytes from registers 0xF6 and 0xF7
ut = bmp085ReadInt(0xF6);
return ut;
}
//----------------------------------------------------------------------------------------------------------
// Read the uncompensated pressure value
unsigned long bmp085ReadUP()
{
unsigned char msb, lsb, xlsb;
unsigned long up = 0;
// Write 0x34+(OSS<<6) into register 0xF4
// Request a pressure reading w/ oversampling setting
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF4);
Wire.write(0x34 + (OSS<<6));
Wire.endTransmission();
// Wait for conversion, delay time dependent on OSS
delay(2 + (3<<OSS));
// Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF6);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 3);
// Wait for data to become available
while(Wire.available() < 3)
;
msb = Wire.read();
lsb = Wire.read();
xlsb = Wire.read();
up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);
return up;
}
//----------------------------------------------------------------------------------------------------------