File content as of revision 0:d07617f8ede9:

/*
 * mbed library to use a Bosch Sensortec BMP085 sensor
 * Copyright (c) 2010 Hiroshi Suga
 * Released under the MIT License: http://mbed.org/license/mit
 */

/** @file BMP085.cpp
 * @brief mbed library to use a Bosch Sensortec BMP085 sensor
 * barometric pressure sensor BMP085 (Bosch Sensortec)
 * interface: I2C digital
 */

#include "mbed.h"
#include "BMP085.h"

#define WEATHER_BMP085 0xee
#define xpow(x, y) ((long)1 << y)

/**
 * @brief Initializes interface (private I2C)
 * @param p_sda port of I2C SDA
 * @param p_scl port of I2C SCL
 * @param p_oss parameter of OSS
 */
BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) 
{
    init(p_oss);
    ok=0;
}

/**
 * @brief Initializes interface (public I2C)
 * @param p_i2c instance of I2C class
 * @param p_oss parameter of OSS
 */
BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) 
{ 
    init(p_oss);
    ok=0;
}

/**
 * @brief Get temperature
 * @return temperature (`C)
 */
float BMP085::get_temperature() 
{
    return temperature;
}

/**
 * @brief Get pressure
 * @return pressure (hPa)
 */
float BMP085::get_pressure() 
{
    return pressure;
}
/**
 * @brief Get altitude e
 * @return altitude (m)
 */
float BMP085::get_altitude() 
{
    return altitude;
}


/**
 * @brief Update results
 */
void BMP085::update () 
{
   static long t, p, ut, up, x1, x2, x3, b3, b5, b6;
   static unsigned long b4, b7;
   static unsigned int nbtick=0;

    switch(nbtick){
        case 0 : twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
                 nbtick=1;
                 break;
        case 1 : ut = twi_readshort(WEATHER_BMP085, 0xf6);
                 twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
                 nbtick=2;
                 break;
        case 2 :
        case 3 :
        case 4 :
        case 5 :
        case 6 :
        //case 7 : 
                 nbtick++;
                 break;
        case 7 : up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);
                 x1 = (ut - ac6) * ac5 / xpow(2, 15);
                 x2 = (long)mc * xpow(2, 11) / (x1 + md);
                 b5 = x1 + x2;
                 t = (b5 + 8) / xpow(2, 4);
                 temperature = (float)t / 10.0;
                 b6 = b5 - 4000;
                 x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);
                 x2 = ac2 * b6 / xpow(2, 11);
                 x3 = x1 + x2;
                 b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;
                 x1 = ac3 * b6 / xpow(2, 13);
                 x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);
                 x3 = ((x1 + x2) + 2) / xpow(2, 2);
                 b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15);
                 b7 = ((unsigned long)up - b3) * (50000 >> oss);
                 if (b7 < (unsigned long)0x80000000) {
                        p = (b7 * 2) / b4;
                 } else {
                        p = (b7 / b4) * 2;
                 }
                 x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));
                 x1 = (x1 * 3038) / xpow(2, 16);
                 x2 = (-7357 * p) / xpow(2, 16);
                 p = p + (x1 + x2 + 3791) / xpow(2, 4);
                 pressure = (float)p / 100.0;
                 ok=1;
                 nbtick=0;
                 break;
         default: nbtick=0; 
                  break;
      }
    /*float To=231; // 298    273,15 + 25
    float ho=0;
    float Po=102400; //101325
    //ecuacion
    float c=(To-0.0065*ho);
    float e=(p/Po);
    float d=exp(0.19082*log(e));  
    float b=c*d;
    altitude = 153.84615*(To-b); 
    
   /*altitude = (float)44330 * (1 - pow(((float) pressure/Po), 0.190295));
    float A = pressure/1024.00;
    float B = 1/5.25588;
    altitude = pow(A,B);
    altitude = 1 - altitude;
    altitude = altitude /0.0000225577;*/
    
    


    
}

void BMP085::init (BMP085_oss p_oss) {
    ac1 = twi_readshort(WEATHER_BMP085, 0xaa);
    ac2 = twi_readshort(WEATHER_BMP085, 0xac);
    ac3 = twi_readshort(WEATHER_BMP085, 0xae);
    ac4 = twi_readshort(WEATHER_BMP085, 0xb0);
    ac5 = twi_readshort(WEATHER_BMP085, 0xb2);
    ac6 = twi_readshort(WEATHER_BMP085, 0xb4);
    b1 = twi_readshort(WEATHER_BMP085, 0xb6);
    b2 = twi_readshort(WEATHER_BMP085, 0xb8);
    mb = twi_readshort(WEATHER_BMP085, 0xba);
    mc = twi_readshort(WEATHER_BMP085, 0xbc);
    md = twi_readshort(WEATHER_BMP085, 0xbe);
    oss = p_oss;
}

unsigned short BMP085::twi_readshort (int id, int addr) {
    unsigned short i;

    i2c.start();
    i2c.write(id);
    i2c.write(addr);

    i2c.start();
    i2c.write(id | 1);
    i = i2c.read(1) << 8;
    i |= i2c.read(0);
    i2c.stop();

    return i;
}

unsigned long BMP085::twi_readlong (int id, int addr) {
    unsigned long i;

    i2c.start();
    i2c.write(id);
    i2c.write(addr);

    i2c.start();
    i2c.write(id | 1);
    i = i2c.read(1) << 16;
    i |= i2c.read(1) << 8;
    i |= i2c.read(0);
    i2c.stop();

    return i;
}

void BMP085::twi_writechar (int id, int addr, int dat)
 {

    i2c.start();
    i2c.write(id);
    i2c.write(addr);
    i2c.write(dat);
    i2c.stop();
}