Exemple code I2C bmp085 pressure sensor

.from: https://github.com/codebendercc/arduino-files/blob/master/extra-libraries/ArduSat-I2Csensors/bmp085.cpp

X=========================X bmp085.h X=========================X

/*

bmp085.h

libary for using the I2C bmp085 pressure sensor

(c) Written by Jeroen Cappaert for NanoSatisfi, August 2012

*/

#ifndef bmp085_h

#define bmp085_h

#include <Arduino.h>

#define BAR_ADDR 0x77 // Barometric pressure sensor I2C address

class bmp085

{

 public:

   //constructor

    bmp085();

    //functions

    void configBaro();

    int bmp085ReadInt(int device, byte address);

    unsigned int baroReadUT();

    unsigned long baroReadUP();

    float getTempFromBaro(unsigned int ut);

    long getPressFromBaro(unsigned long up);

    void getBmpData(float bmp[]);

    //variables

    int ac1;

    int ac2;

    int ac3;

    unsigned int ac4;

    unsigned int ac5;

    unsigned int ac6;

    int b1;

    int b2;

    int mb;

    int mc;

    int md;

    int barOSS;

    long b5;

  private:

};

#endif

X=========================X bmp085.cpp X=========================X

/*

bmp085.cpp

libary for using the I2C bmp085 pressure sensor

(c) Written by Jeroen Cappaert for NanoSatisfi, August 2012

*/

#include <Arduino.h>

#include "bmp085.h"

#include <Wire.h>

//Constructor

bmp085::bmp085()

{

  barOSS = 2;

}

//configure barometer

void bmp085::configBaro()

{

  ac1 = bmp085ReadInt(BAR_ADDR, 0xAA);

  ac2 = bmp085ReadInt(BAR_ADDR, 0xAC);

  ac3 = bmp085ReadInt(BAR_ADDR, 0xAE);

  ac4 = bmp085ReadInt(BAR_ADDR, 0xB0);

  ac5 = bmp085ReadInt(BAR_ADDR, 0xB2);

  ac6 = bmp085ReadInt(BAR_ADDR, 0xB4);

  b1 = bmp085ReadInt(BAR_ADDR, 0xB6);

  b2 = bmp085ReadInt(BAR_ADDR, 0xB8);

  mb = bmp085ReadInt(BAR_ADDR, 0xBA);

  mc = bmp085ReadInt(BAR_ADDR, 0xBC);

  md = bmp085ReadInt(BAR_ADDR, 0xBE);

}

// user function: get pressure and temperature from sensor with one command

void bmp085::getBmpData(float bmp[])

{

 bmp[0] = getTempFromBaro(baroReadUT());

 bmp[1] = getPressFromBaro(baroReadUP());

}

// calculate temperature given ut

float bmp085::getTempFromBaro(unsigned int ut)

{

  long x1, x2;

  

  x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;

  x2 = ((long)mc << 11)/(x1 + md);

  b5 = x1 + x2;

  return (float) ((b5 + 8)>>4)/10.;

}

// 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 bmp085::getPressFromBaro(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)<<barOSS) + 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>>barOSS));

  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 uncorrected temperature value from bmp085

unsigned int bmp085::baroReadUT()

{

  unsigned int ut;

  

  // Write 0x2E into Register 0xF4

  // This requests a temperature reading

  Wire.beginTransmission(BAR_ADDR);

  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(BAR_ADDR,0xF6);

  return ut;

}

// read uncorrected pressure value from bmp085

unsigned long bmp085::baroReadUP()

{

  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(BAR_ADDR);

  Wire.write(0xF4);

  Wire.write(0x34 + (barOSS<<6));

  Wire.endTransmission();

  

  // Wait for conversion, delay time dependent on OSS

  delay(2 + (3<<barOSS));

  

  // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)

  Wire.beginTransmission(BAR_ADDR);

  Wire.write(0xF6);

  Wire.endTransmission();

  Wire.requestFrom(BAR_ADDR,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-barOSS);

  

  return up;

}

// read integer on bmp085

int bmp085::bmp085ReadInt(int device, byte address)

{

  unsigned char msb, lsb;

  

  Wire.beginTransmission(device);

  Wire.write(address);

  Wire.endTransmission();

  

  Wire.requestFrom(device, 2);

  while(Wire.available()<2)

    ;

  msb = Wire.read();

  lsb = Wire.read();

  

  return (int) msb<<8 | lsb;

}

X=========================X X=========================X