Bear_BMP085.cpp

/***************************************************
  This is a library 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
 ****************************************************/

#include "Bear_BMP085.h"

//#define BMP085_DEBUG 1
BMP085::BMP085() {
}


boolean BMP085::begin(uint8_t mode) {
  if (mode > BMP085_ULTRAHIGHRES)
    mode = BMP085_ULTRAHIGHRES;
  oversampling = mode;
  Wire.begin();

  if (read8(0xD0) != 0x55) 
  {
    initSuccess =false;
    return false;
  }

  /* read calibration data */
  ac1 = read16(BMP085_CAL_AC1);
  ac2 = read16(BMP085_CAL_AC2);
  ac3 = read16(BMP085_CAL_AC3);
  ac4 = read16(BMP085_CAL_AC4);
  ac5 = read16(BMP085_CAL_AC5);
  ac6 = read16(BMP085_CAL_AC6);

  b1 = read16(BMP085_CAL_B1);
  b2 = read16(BMP085_CAL_B2);

  mb = read16(BMP085_CAL_MB);
  mc = read16(BMP085_CAL_MC);
  md = read16(BMP085_CAL_MD);
#if (BMP085_DEBUG == 1)
  Serial.print("ac1 = "); Serial.println(ac1, DEC);
  Serial.print("ac2 = "); Serial.println(ac2, DEC);
  Serial.print("ac3 = "); Serial.println(ac3, DEC);
  Serial.print("ac4 = "); Serial.println(ac4, DEC);
  Serial.print("ac5 = "); Serial.println(ac5, DEC);
  Serial.print("ac6 = "); Serial.println(ac6, DEC);

  Serial.print("b1 = "); Serial.println(b1, DEC);
  Serial.print("b2 = "); Serial.println(b2, DEC);

  Serial.print("mb = "); Serial.println(mb, DEC);
  Serial.print("mc = "); Serial.println(mc, DEC);
  Serial.print("md = "); Serial.println(md, DEC);
#endif

  return  true;
}

uint16_t BMP085::readRawTemperature(void) {
  if (!initSuccess) return 0;
  write8(BMP085_CONTROL, BMP085_READTEMPCMD);
  delay(5);
#if BMP085_DEBUG == 1
  Serial.print("Raw temp: "); Serial.println(read16(BMP085_TEMPDATA));
#endif
  return read16(BMP085_TEMPDATA);
}

uint32_t BMP085::readRawPressure(void) {
  if (!initSuccess) return 0;
  uint32_t raw;

  write8(BMP085_CONTROL, BMP085_READPRESSURECMD + (oversampling << 6));

  if (oversampling == BMP085_ULTRALOWPOWER)
    delay(5);
  else if (oversampling == BMP085_STANDARD)
    delay(8);
  else if (oversampling == BMP085_HIGHRES)
    delay(14);
  else
    delay(26);

  raw = read16(BMP085_PRESSUREDATA);

  raw <<= 8;
  raw |= read8(BMP085_PRESSUREDATA + 2);
  raw >>= (8 - oversampling);

  /* this pull broke stuff, look at it later?
    if (oversampling==0) {
     raw <<= 8;
     raw |= read8(BMP085_PRESSUREDATA+2);
     raw >>= (8 - oversampling);
    }
  */

#if BMP085_DEBUG == 1
  Serial.print("Raw pressure: "); Serial.println(raw);
#endif
  return raw;
}


int32_t BMP085::readPressure(void) {
  if (!initSuccess) return 0;
  int32_t UT, UP, B3, B5, B6, X1, X2, X3, p;
  uint32_t B4, B7;

  UT = readRawTemperature();
  UP = readRawPressure();

  /*#if BMP085_DEBUG == 1
    // use datasheet numbers!
    UT = 27898;
    UP = 23843;
    ac6 = 23153;
    ac5 = 32757;
    mc = -8711;
    md = 2868;
    b1 = 6190;
    b2 = 4;
    ac3 = -14383;
    ac2 = -72;
    ac1 = 408;
    ac4 = 32741;
    oversampling = 0;
    #endif*/

  // do temperature calculations
  X1 = (UT - (int32_t)(ac6)) * ((int32_t)(ac5)) / pow(2, 15);
  X2 = ((int32_t)mc * pow(2, 11)) / (X1 + (int32_t)md);
  B5 = X1 + X2;

#if BMP085_DEBUG == 1
  Serial.print("X1 = "); Serial.println(X1);
  Serial.print("X2 = "); Serial.println(X2);
  Serial.print("B5 = "); Serial.println(B5);
#endif

  // do pressure calcs
  B6 = B5 - 4000;
  X1 = ((int32_t)b2 * ( (B6 * B6) >> 12 )) >> 11;
  X2 = ((int32_t)ac2 * B6) >> 11;
  X3 = X1 + X2;
  B3 = ((((int32_t)ac1 * 4 + X3) << oversampling) + 2) / 4;

#if BMP085_DEBUG == 1
  Serial.print("B6 = "); Serial.println(B6);
  Serial.print("X1 = "); Serial.println(X1);
  Serial.print("X2 = "); Serial.println(X2);
  Serial.print("B3 = "); Serial.println(B3);
#endif

  X1 = ((int32_t)ac3 * B6) >> 13;
  X2 = ((int32_t)b1 * ((B6 * B6) >> 12)) >> 16;
  X3 = ((X1 + X2) + 2) >> 2;
  B4 = ((uint32_t)ac4 * (uint32_t)(X3 + 32768)) >> 15;
  B7 = ((uint32_t)UP - B3) * (uint32_t)( 50000UL >> oversampling );

#if BMP085_DEBUG == 1
  Serial.print("X1 = "); Serial.println(X1);
  Serial.print("X2 = "); Serial.println(X2);
  Serial.print("B4 = "); Serial.println(B4);
  Serial.print("B7 = "); Serial.println(B7);
#endif

  if (B7 < 0x80000000) {
    p = (B7 * 2) / B4;
  } else {
    p = (B7 / B4) * 2;
  }
  X1 = (p >> 8) * (p >> 8);
  X1 = (X1 * 3038) >> 16;
  X2 = (-7357 * p) >> 16;

#if BMP085_DEBUG == 1
  Serial.print("p = "); Serial.println(p);
  Serial.print("X1 = "); Serial.println(X1);
  Serial.print("X2 = "); Serial.println(X2);
#endif

  p = p + ((X1 + X2 + (int32_t)3791) >> 4);
#if BMP085_DEBUG == 1
  Serial.print("p = "); Serial.println(p);
#endif
  return p;
}


float BMP085::readTemperature(void) {
  if (!initSuccess) return 0;
  int32_t UT, X1, X2, B5;     // following ds convention
  float temp;

  UT = readRawTemperature();

#if BMP085_DEBUG == 1
  // use datasheet numbers!
  UT = 27898;
  ac6 = 23153;
  ac5 = 32757;
  mc = -8711;
  md = 2868;
#endif

  // step 1
  X1 = (UT - (int32_t)ac6) * ((int32_t)ac5) / pow(2, 15);
  X2 = ((int32_t)mc * pow(2, 11)) / (X1 + (int32_t)md);
  B5 = X1 + X2;
  temp = (B5 + 8) / pow(2, 4);
  temp /= 10;

  return temp;
}

float BMP085::readAltitude(float sealevelPressure) {
  if (!initSuccess) return 0;
  float altitude;

  float pressure = readPressure();

  altitude = 44330 * (1.0 - pow(pressure / sealevelPressure, 0.1903));

  return altitude;
}


/*********************************************************************/

uint8_t BMP085::read8(uint8_t a) {
  if (!initSuccess) return 0;
  uint8_t ret;

  Wire.beginTransmission(BMP085_I2CADDR); // start transmission to device
#if (ARDUINO >= 100)
  Wire.write(a); // sends register address to read from
#else
  Wire.send(a); // sends register address to read from
#endif
  Wire.endTransmission(); // end transmission

  // Wire.beginTransmission(BMP085_I2CADDR); // start transmission to device
  Wire.requestFrom(BMP085_I2CADDR, 1);// send data n-bytes read
#if (ARDUINO >= 100)
  ret = Wire.read(); // receive DATA
#else
  ret = Wire.receive(); // receive DATA
#endif
  // Wire.endTransmission(); // end transmission

  return ret;
}

uint16_t BMP085::read16(uint8_t a) {
  if (!initSuccess) return 0;
  uint16_t ret;

  Wire.beginTransmission(BMP085_I2CADDR); // start transmission to device
#if (ARDUINO >= 100)
  Wire.write(a); // sends register address to read from
#else
  Wire.send(a); // sends register address to read from
#endif
  Wire.endTransmission(true); // end transmission

  //Wire.beginTransmission(BMP085_I2CADDR); // start transmission to device
  Wire.requestFrom(BMP085_I2CADDR, 2);// send data n-bytes read
#if (ARDUINO >= 100)
  ret = Wire.read(); // receive DATA
  ret <<= 8;
  ret |= Wire.read(); // receive DATA
#else
  ret = Wire.receive(); // receive DATA
  ret <<= 8;
  ret |= Wire.receive(); // receive DATA
#endif
  //Wire.endTransmission(); // end transmission

  return ret;
}

void BMP085::write8(uint8_t a, uint8_t d) {
  if (!initSuccess) return ;
  Wire.beginTransmission(BMP085_I2CADDR); // start transmission to device
#if (ARDUINO >= 100)
  Wire.write(a); // sends register address to read from
  Wire.write(d);  // write data
#else
  Wire.send(a); // sends register address to read from
  Wire.send(d);  // write data
#endif
  Wire.endTransmission(true); // end transmission
}