File content as of revision 0:ad2afb285975:

/*
   * 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);
  }
  
  /**
   * @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);
  }
  
  /**
   * @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 Update results
   */
  void BMP085::update () {
      long t, p, ut, up, x1, x2, x3, b3, b5, b6;
      unsigned long b4, b7;
  
      twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
      wait(0.01);
      ut = twi_readshort(WEATHER_BMP085, 0xf6);
  
      twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
      wait(0.05);
      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;
  }
  
  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();
  }