//
//    FILE: DS18B20.cpp
//  AUTHOR: Rob.Tillaart@gmail.com
// VERSION: 0.1.0
//    DATE: 2017-07-25
//
// PUPROSE: library for DS18B20 temperature sensor with minimal footprint
//
// HISTORY:
// 0.1.0 = 2017-07-25 initial version

#include "Arduino.h"
#include "DS18B20.h"

// OneWire commands
#define STARTCONVO      0x44
#define READSCRATCH     0xBE
#define WRITESCRATCH    0x4E

// Scratchpad locations
#define TEMP_LSB        0
#define TEMP_MSB        1
// #define HIGH_ALARM_TEMP 2
// #define LOW_ALARM_TEMP  3
// #define CONFIGURATION   4
// #define INTERNAL_BYTE   5
// #define COUNT_REMAIN    6
// #define COUNT_PER_C     7
// #define SCRATCHPAD_CRC  8

// Device resolution
#define TEMP_9_BIT  0x1F //  9 bit
#define TEMP_10_BIT 0x3F // 10 bit
#define TEMP_11_BIT 0x5F // 11 bit
#define TEMP_12_BIT 0x7F // 12 bit


DS18B20::DS18B20(OneWire* _oneWire)
{
  _wire = _oneWire;
}

bool DS18B20::begin(void)
{
  _wire->reset_search();
  _wire->search(deviceAddress);
  return (_wire->crc8(deviceAddress, 7) == deviceAddress[7]);
}

void DS18B20::readScratchPad(uint8_t *scratchPad, uint8_t fields)
{
  _wire->reset();
  _wire->select(deviceAddress);
  _wire->write(READSCRATCH);

  for(uint8_t i=0; i < fields; i++)
  {
    scratchPad[i] = _wire->read();
  }
  _wire->reset();
}

bool DS18B20::isConversionComplete(void)
{
  return (_wire->read_bit() == 1);
}	

void DS18B20::requestTemperatures(void)
{
  _wire->reset();
  _wire->skip();
  _wire->write(STARTCONVO, 0);
}

float DS18B20::getTempC(void)
{
  ScratchPad scratchPad;
  readScratchPad(scratchPad, 2);

  int16_t rawTemperature = (((int16_t)scratchPad[TEMP_MSB]) << 8) | scratchPad[TEMP_LSB];

  float temp = 0.0625 * rawTemperature;
  if (temp < -55) return DEVICE_DISCONNECTED;
  return temp;
}

void DS18B20::setResolution(uint8_t newResolution)
{
  _wire->reset();
  _wire->select(deviceAddress);
  _wire->write(WRITESCRATCH);
  // two dummy values for LOW & HIGH ALARM
  _wire->write(0);
  _wire->write(100);
  switch (newResolution)
  {
  case 12:
    _wire->write(TEMP_12_BIT);
    break;
  case 11:
    _wire->write(TEMP_11_BIT);
    break;
  case 10:
    _wire->write(TEMP_10_BIT);
    break;
  case 9:
  default:
    _wire->write(TEMP_9_BIT);
    break;
  }
  _wire->reset();
}

//  END OF FILE