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/****************************************************************************
* BMP085.cpp - BMP085/I2C (Digital Pressure Sensor) library for Arduino *
* Copyright 2010-2011 Filipe Vieira & various contributors *
* *
* This file is part of BMP085 Arduino library. *
* *
* This library is free software: you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as published *
* by the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
****************************************************************************/
/****************************************************************************
* Tested on Arduino Mega with BMP085 Breakout *
* SDA -> pin 20 (no pull up resistors) *
* SCL -> pin 21 (no pull up resistors) *
* XCLR -> not connected *
* EOC -> not connected *
* GND -> pin GND *
* VCC -> pin 3.3V *
* NOTE: SCL and SDA needs pull-up resistors for each I2C bus. *
* 2.2kOhm..10kOhm, typ. 4.7kOhm *
*****************************************************************************/
#include <Wire.h>
#include <BMP085.h>
BMP085::BMP085() {
_dev_address = BMP085_ADDR;
_pressure_waittime[0] = 5; // These are maximum convertion times.
_pressure_waittime[1] = 8; // It is possible to use pin EOC (End Of Conversion)
_pressure_waittime[2] = 14;// to check if conversion is finished (logic 1)
_pressure_waittime[3] = 26;// or running (logic 0) insted of waiting for convertion times.
_cm_Offset = 0;
_Pa_Offset = 0; // 1hPa = 100Pa = 1mbar
oldEMA = 0;
}
void BMP085::init() {
init(MODE_STANDARD, 0, true);
}
void BMP085::init(byte _BMPMode, int32_t _initVal, bool _Unitmeters){
getCalData(); // initialize cal data
calcTrueTemperature(); // initialize b5
setMode(_BMPMode);
_Unitmeters ? setLocalAbsAlt(_initVal) : setLocalPressure(_initVal);
}
byte BMP085::getDevAddr() {
return _dev_address;
}
byte BMP085::getMode(){
return _oss;
}
void BMP085::setMode(byte _BMPMode){
_oss = _BMPMode;
}
void BMP085::setLocalPressure(int32_t _Pa){
int32_t tmp_alt;
_param_datum = _Pa;
getAltitude(&tmp_alt); // calc altitude based on current pressure
_param_centimeters = tmp_alt;
}
void BMP085::setLocalAbsAlt(int32_t _centimeters){
int32_t tmp_Pa;
_param_centimeters = _centimeters;
getPressure(&tmp_Pa); // calc pressure based on current altitude
_param_datum = tmp_Pa;
}
void BMP085::setAltOffset(int32_t _centimeters){
_cm_Offset = _centimeters;
}
void BMP085::sethPaOffset(int32_t _Pa){
_Pa_Offset = _Pa;
}
void BMP085::zeroCal(int32_t _Pa, int32_t _centimeters){
setAltOffset(_centimeters - _param_centimeters);
sethPaOffset(_Pa - _param_datum);
}
void BMP085::getPressure(int32_t *_Pa){
long TruePressure;
calcTruePressure(&TruePressure);
*_Pa = TruePressure / pow((1 - (float)_param_centimeters / 4433000), 5.255) + _Pa_Offset;
// converting from float to int32_t truncates toward zero, 1010.999985 becomes 1010 resulting in 1 Pa error (max).
// Note that BMP085 abs accuracy from 700...1100hPa and 0..+65ºC is +-100Pa (typ.)
}
void BMP085::getAltitude(int32_t *_centimeters){
long TruePressure;
calcTruePressure(&TruePressure);
*_centimeters = 4433000 * (1 - pow((TruePressure / (float)_param_datum), 0.1903)) + _cm_Offset;
// converting from float to int32_t truncates toward zero, 100.999985 becomes 100 resulting in 1 cm error (max).
}
void BMP085::getTemperature(int32_t *_Temperature) {
calcTrueTemperature(); // force b5 update
*_Temperature = ((b5 + 8) >> 4);
}
void BMP085::calcTrueTemperature(){
long ut,x1,x2;
//read Raw Temperature
writemem(CONTROL, READ_TEMPERATURE);
delayMicroseconds(4500); // min. 4.5ms read Temp delay
readmem(CONTROL_OUTPUT, 2, _buff);
ut = ((long)_buff[0] << 8 | ((long)_buff[1])); // uncompensated temperature value
// calculate temperature
x1 = ((long)ut - ac6) * ac5 >> 15;
x2 = ((long)mc << 11) / (x1 + md);
b5 = x1 + x2;
}
void BMP085::calcTruePressure(long *_TruePressure) {
long up,x1,x2,x3,b3,b6,p;
unsigned long b4,b7;
int32_t tmp;
#if AUTO_UPDATE_TEMPERATURE
calcTrueTemperature(); // b5 update
#endif
//read Raw Pressure
writemem(CONTROL, READ_PRESSURE+(_oss << 6));
delay(_pressure_waittime[_oss]);
readmem(CONTROL_OUTPUT, 3, _buff);
up = ((((long)_buff[0] <<16) | ((long)_buff[1] <<8) | ((long)_buff[2])) >> (8-_oss)); // uncompensated pressure value
// calculate true pressure
b6 = b5 - 4000; // b5 is updated by calcTrueTemperature().
x1 = (b2* (b6 * b6 >> 12)) >> 11;
x2 = ac2 * b6 >> 11;
x3 = x1 + x2;
tmp = ac1;
tmp = (tmp * 4 + x3) << _oss;
b3 = (tmp + 2) >> 2;
x1 = ac3 * b6 >> 13;
x2 = (b1 * (b6 * b6 >> 12)) >> 16;
x3 = ((x1 + x2) + 2) >> 2;
b4 = (ac4 * (uint32_t) (x3 + 32768)) >> 15;
b7 = ((uint32_t)up - b3) * (50000 >> _oss);
p = b7 < 0x80000000 ? (b7 << 1) / b4 : (b7 / b4) << 1;
x1 = (p >> 8) * (p >> 8);
x1 = (x1 * 3038) >> 16;
x2 = (-7357 * p) >> 16;
*_TruePressure = p + ((x1 + x2 + 3791) >> 4);
}
void BMP085::dumpCalData() {
Serial.println("---cal data start---");
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);
Serial.println("---cal data end---");
}
//PRIVATE methods
void BMP085::getCalData() {
readmem(CAL_AC1, 2, _buff);
ac1 = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_AC2, 2, _buff);
ac2 = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_AC3, 2, _buff);
ac3 = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_AC4, 2, _buff);
ac4 = ((unsigned int)_buff[0] <<8 | ((unsigned int)_buff[1]));
readmem(CAL_AC5, 2, _buff);
ac5 = ((unsigned int)_buff[0] <<8 | ((unsigned int)_buff[1]));
readmem(CAL_AC6, 2, _buff);
ac6 = ((unsigned int)_buff[0] <<8 | ((unsigned int)_buff[1]));
readmem(CAL_B1, 2, _buff);
b1 = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_B2, 2, _buff);
b2 = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_MB, 2, _buff);
mb = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_MC, 2, _buff);
mc = ((int)_buff[0] <<8 | ((int)_buff[1]));
readmem(CAL_MD, 2, _buff);
md = ((int)_buff[0] <<8 | ((int)_buff[1]));
}
void BMP085::writemem(uint8_t _addr, uint8_t _val) {
Wire.beginTransmission(_dev_address); // start transmission to device
Wire.send(_addr); // send register address
Wire.send(_val); // send value to write
Wire.endTransmission(); // end transmission
}
void BMP085::readmem(uint8_t _addr, uint8_t _nbytes, uint8_t __buff[]) {
Wire.beginTransmission(_dev_address); // start transmission to device
Wire.send(_addr); // sends register address to read from
Wire.endTransmission(); // end transmission
Wire.beginTransmission(_dev_address); // start transmission to device
Wire.requestFrom(_dev_address, _nbytes);// send data n-bytes read
uint8_t i = 0;
while (Wire.available()) {
__buff[i] = Wire.receive(); // receive DATA
i++;
}
Wire.endTransmission(); // end transmission
}