/*
 *  lm75a.cpp: part of the "VoluMaster(tm)" system
 *
 *  An open-source arduino controller-based digital volume control and input/output selector
 *
 *
 *  LICENSE
 *  -------
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 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 "lm75a.h"

#include <Wire.h>
#include <stdio.h>  //not needed yet
#include <string.h> //needed for strlen()
#include <inttypes.h>

#include "WConstants.h"  //all things wiring / arduino


#include "config.h"





// ctor
LM75A::LM75A( uint8_t passed_i2c_addr )
{
  my_dev_addr = passed_i2c_addr;
}




void
LM75A::init( void )
{
}




#if 0
void
LM75A::set( uint8_t reg, uint8_t val )
{
  Wire.beginTransmission(my_dev_addr);

  Wire.send(reg);
  Wire.send(val);

  Wire.endTransmission();
}
#endif




float
LM75A::get_temp( void ) 
{
  unsigned int val = 0;
  unsigned int shifted = 0;
  float val_f = 0.0;
  

  Wire.beginTransmission(my_dev_addr);
  Wire.send(0x00);  // 0 = 'temperature register' and this implies that we expect 2 bytes (msb, lsb) in return to our request
  Wire.endTransmission();


  Wire.requestFrom((uint8_t)my_dev_addr, (uint8_t)2);  // read 2 bytes
  while (Wire.available() < 2) { }  // note the null loop!
  
  val = (Wire.receive() << 8);          // MSB
  val |= Wire.receive();                // LSB
  
  // now, deal with the funky lm75a bit-shifting
  shifted = (val >> 5);
  
  // NOTE!!! I'm making a big assumption here; that the MS bit (highest bit in MS byte) is not 1 and therefore this is not
  // a 2's compliment number.  this only happens when you are below 0 in binary value (0 binary == 0C, 1 binary == 0.125C, etc)
  // for room temperature electronics, we should rarely see freezing temperatures (lol)
  
  val_f = (float)shifted * 0.125;

  return val_f;
}