File content as of revision 7:8545a1d1d1e4:

/*
MS5611-01BA.cpp - Interfaces a Measurement Specialities MS5611-01BA with Arduino
See http://www.meas-spec.com/downloads/MS5611-01BA01.pdf for the device datasheet

Copyright (C) 2011 Fabio Varesano <fvaresano@yahoo.it>

Development of this code has been supported by the Department of Computer Science,
Universita' degli Studi di Torino, Italy within the Piemonte Project
http://www.piemonte.di.unito.it/


This program is free software: you can redistribute it and/or modify
it under the terms of the version 3 GNU General Public License as
published by the Free Software Foundation.

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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "mbed.h"
#include "MS561101BA.h"
#define CONVERSION_TIME 12000l // conversion time in microseconds

MS561101BA::MS561101BA():i2c(I2C_SDA,I2C_SCL){
}

MS561101BA::MS561101BA(I2C _i2c):i2c(_i2c) {
  ;
}

void MS561101BA::init(uint8_t address) {  
lastPresConv=0;
lastTempConv=0;
  t.start();
  _addr =  address;
 
  reset(); // reset the device to populate its internal PROM registers
  wait_ms(500); // some safety time
  readPROM(); // reads the PROM into object variables for later use
}

float MS561101BA::getPressure(uint8_t OSR) {
  // see datasheet page 7 for formulas
  
  uint32_t rawPress = rawPressure(OSR);
  if(rawPress == NULL) {
    return NULL;
  }
  
  int32_t dT = getDeltaTemp(OSR);
  if(dT == NULL) {
    return NULL;
  }
  
  int64_t off  = ((uint32_t)_Cal[1] <<16) + (((int64_t)dT * _Cal[3]) >> 7);
  int64_t sens = ((uint32_t)_Cal[0] <<15) + (((int64_t)dT * _Cal[2]) >> 8);
  return ((( (rawPress * sens ) >> 21) - off) >> 15) / 100.0;
}

float MS561101BA::getTemperature(uint8_t OSR) {
  // see datasheet page 7 for formulas
  int64_t dT = getDeltaTemp(OSR);
  
  if(dT != NULL) {
    return (2000 + ((dT * _Cal[5]) >> 23)) / 100.0;
  }
  else {
    return NULL;
  }
}

int32_t MS561101BA::getDeltaTemp(uint8_t OSR) {
  uint32_t rawTemp = rawTemperature(OSR);
  if(rawTemp != NULL) {
    return (int32_t)(rawTemp - ((uint32_t)_Cal[4] << 8));
  }
  else {
    return NULL;
  }
}

//TODO: avoid duplicated code between rawPressure and rawTemperature methods
//TODO: possible race condition between readings.. serious headache doing this.. help appreciated!

uint32_t MS561101BA::rawPressure(uint8_t OSR) {
  uint32_t now = t.read_us();
  if(lastPresConv != 0 && (now - lastPresConv) >= CONVERSION_TIME) {
    lastPresConv = 0;
    pressCache = getConversion(MS561101BA_D1 + OSR);
  }
  else {
    if(lastPresConv == 0 && lastTempConv == 0) {
      startConversion(MS561101BA_D1 + OSR);
      lastPresConv = now;
    }
  }
  return pressCache;
}

uint32_t MS561101BA::rawTemperature(uint8_t OSR) {
  unsigned long now = t.read_us();
  if(lastTempConv != 0 && (now - lastTempConv) >= CONVERSION_TIME) {
    lastTempConv = 0;
    tempCache = getConversion(MS561101BA_D2 + OSR);
  }
  else {
    if(lastTempConv == 0 && lastPresConv == 0) { // no conversions in progress
      startConversion(MS561101BA_D2 + OSR);
      lastTempConv = now;
    }
  }
  return tempCache;
}


// see page 11 of the datasheet
void MS561101BA::startConversion(uint8_t command) {
  // initialize pressure conversion
  i2c.start();
  i2c.write(_addr<<1);
  i2c.write(command);
  i2c.stop();
}

uint32_t MS561101BA::getConversion(uint8_t command) {
  uint32_t conversion = 0;
  
  // start read sequence
  /*Wire.beginTransmission(_addr);
  Wire.write(0);
  Wire.endTransmission();*/
  i2c.start();
  i2c.write(_addr<<1);
  i2c.write(0);
  i2c.stop();
  
  //Wire.beginTransmission(_addr);
  //Wire.requestFrom(_addr, (uint8_t) MS561101BA_D1D2_SIZE);
  char cobuf[3];
  if (i2c.read((_addr<<1)+1, cobuf, MS561101BA_D1D2_SIZE)!=0) {conversion=0xFFFFFFFF;}else{
    conversion = (cobuf[0] << 16) + (cobuf[1] << 8) + cobuf[2];
  }
  return conversion;
}


/**
 * Reads factory calibration and store it into object variables.
*/
int MS561101BA::readPROM() {
  for (int i=0;i<MS561101BA_PROM_REG_COUNT;i++) {
    /*Wire.beginTransmission(_addr);
    Wire.write(MS561101BA_PROM_BASE_ADDR + (i * MS561101BA_PROM_REG_SIZE));
    Wire.endTransmission();*/
    i2c.start();
    i2c.write(_addr<<1);
    i2c.write(MS561101BA_PROM_BASE_ADDR + (i * MS561101BA_PROM_REG_SIZE));
    i2c.stop();
    
    char tmp[2];
    if (i2c.read((_addr<<1)+1, tmp, MS561101BA_PROM_REG_SIZE)!=0) return -1;
    _Cal[i] = tmp[0]<<8 | tmp[1];
    wait_ms(200);
  }
  return 0;
}


/**
 * Send a reset command to the device. With the reset command the device
 * populates its internal registers with the values read from the PROM.
*/
void MS561101BA::reset() {
  /*Wire.beginTransmission(_addr);
  Wire.write(MS561101BA_RESET);
  Wire.endTransmission();*/
  i2c.start();
  i2c.write(_addr<<1);
  i2c.write(MS561101BA_RESET);
  i2c.stop();
}