BMP085NB.cpp

#include <BMP085NB.h>
#include <Wire.h>

void BMP085NB::pollData (int *temperature, long *pressure, float *alti) {	
  switch (pressureState){
    case 0:
	  pressureState = 1;
	  newData = false;
	  timer = millis();
      StartUT();            
    break;
    case 1:
      if (millis() - timer >= 5) {
        pressureState = 2;
		ut = ReadUT();	
        *temperature = Temperature(ut);        
      }
    break;
    case 2:
      timer1 = millis();
      StartUP();      
      pressureState = 3;
    break;    
    case 3:			  
      if (millis() - timer1 >= 2 + (3<<OSS)) {	          
        up = ReadUP();
        *pressure = Pressure(up);
        *alti = Altitude(*pressure);
		newData = true;
		pressureState = 0;
      }
    break;
	default:
	break;
  }
}

void BMP085NB::setSeaLevelPressure (long seaLevelPressure) {
	slp = seaLevelPressure;
}

short BMP085NB::Temperature(unsigned int ut){ 
  x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
  x2 = ((long)mc << 11)/(x1 + md);
  b5 = x1 + x2;

  return ((b5 + 8)>>4);
}

long BMP085NB::Pressure(unsigned long up) {
  //calculate true pressure
  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;
}

float BMP085NB::Altitude(long pres){
  return (float)44330 * (1 - pow(((float) pres / slp), 0.190295));
}

void BMP085NB::StartUT() {
  writeRegister(0xf4,0x2e);
}

void BMP085NB::StartUP() {
  writeRegister(0xf4,0x34+(OSS<<6));
}

unsigned int BMP085NB::ReadUT() {
  return readIntRegister(0xf6);
}

unsigned long BMP085NB::ReadUP() {  
  unsigned char msb, lsb, xlsb;
  
  Wire.beginTransmission(I2C_ADDRESS);
  Wire.write(0xf6);  // register to read
  Wire.endTransmission();

  Wire.requestFrom(I2C_ADDRESS, 3); // request three bytes
  while(Wire.available() < 3); // wait until data available
  msb = Wire.read();
  lsb = Wire.read();
  xlsb = Wire.read();
  
  return (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);
}

void BMP085NB::initialize () {
  pressureState = 0;
  newData = false;
  slp = SEA_LEVEL_PRESSURE;  
  ac1 = readIntRegister(0xAA);
  ac2 = readIntRegister(0xAC);
  ac3 = readIntRegister(0xAE);
  ac4 = readIntRegister(0xB0);
  ac5 = readIntRegister(0xB2);
  ac6 = readIntRegister(0xB4);
  b1 = readIntRegister(0xB6);
  b2 = readIntRegister(0xB8);
  mb = readIntRegister(0xBA);
  mc = readIntRegister(0xBC);
  md = readIntRegister(0xBE);
}

void BMP085NB::writeRegister(unsigned char r, unsigned char v)
{ 
  Wire.beginTransmission(I2C_ADDRESS);
  Wire.write(r);
  Wire.write(v);
  Wire.endTransmission();
}

int BMP085NB::readIntRegister(unsigned char r)
{
  unsigned char msb, lsb;
  Wire.beginTransmission(I2C_ADDRESS);
  Wire.write(r);  // register to read
  Wire.endTransmission();
  Wire.requestFrom(I2C_ADDRESS, 2); // request two bytes
  while(!Wire.available()); // wait until data available
  msb = Wire.read();
  while(!Wire.available()); // wait until data available
  lsb = Wire.read();
  return (((int)msb<<8) | ((int)lsb));
	
}