/*!
LTC2309: 8-channel, 12-Bit SAR ADC with I2C interface
LTC2301: 1-Channel, 12-Bit ADCs with I2C Compatible Interface

@verbatim

The LTC2309 is a low noise, low power, 8-channel, 12-bit successive
approximation ADC with an I2C compatible serial interface. This ADC includes an
internal reference and a fully differential sample-and-hold circuit to reduce
common mode noise. The LTC2309 operates from an internal clock to achieve a fast
1.3 microsecond conversion time.

The LTC2309 operates from a single 5V supply and draws just 300 microamps at a
throughput rate of 1ksps. The ADC enters nap mode when not converting, reducing
the power dissipation.

@endverbatim

http://www.linear.com/product/LTC2309
http://www.linear.com/product/LTC2301

http://www.linear.com/product/LTC2309#demoboards
http://www.linear.com/product/LTC2301#demoboards


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 - The use of this software may or may not infringe the patent rights
   of one or more patent holders.  This license does not release you
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THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
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*/

//! @ingroup Analog_to_Digital_Converters
//! @{
//! @defgroup LTC2309 LTC2309: 8-channel, 12-Bit SAR ADC with I2C interface
//! @}

/*! @file
    @ingroup LTC2309
    Library for LTC2309: 8-channel, 12-Bit SAR ADC with I2C interface
*/

#include <Arduino.h>
#include <stdint.h>
#include "Linduino.h"
#include "LT_I2C.h"
#include "LTC2309.h"
#include <Wire.h>

// Commands
// Construct a channel / uni/bipolar by bitwise ORing one choice from the channel configuration
// and one choice from the command.

// Example - read channel 3 single-ended
// adc_command = LTC2309_CH3 | LTC2309_UNIPOLAR_MODE;

// Example - read voltage between channels 5 and 4 with 4 as positive polarity and in bipolar mode.
// adc_command = LTC2309_P4_N5 | LTC2309_BIPOLAR_MODE;


// Reads 12 bits in binary format
int8_t LTC2309_read(uint8_t i2c_address, uint8_t adc_command, uint16_t *ptr_adc_code)
{
  int8_t ack = 0;
  LT_union_int16_2bytes data;

  data.LT_byte[1] = 0;
  data.LT_byte[0] = 0;

  ack = i2c_read_word_data(i2c_address, adc_command, &data.LT_uint16);

  *ptr_adc_code = data.LT_uint16; //note the 12 bits of data are left justified

  return(ack);
}


// Calculates the LTC2309 input unipolar voltage.
float LTC2309_code_to_voltage(uint16_t adc_code, float vref, uint8_t uni_bipolar)
{
  float voltage;
  float sign = 1;

  if (uni_bipolar == LTC2309_UNIPOLAR_MODE)
  {
    voltage = (float)adc_code;
    voltage = voltage / (pow(2,16)-1);    //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
  }
  else
  {
    vref = vref/2;
    if ((adc_code & 0x8000) == 0x8000)  //adc code is < 0
    {
      adc_code = (adc_code ^ 0xFFFF)+1;                                    //! Convert ADC code from two's complement to binary
      sign = -1;
    }
    voltage = sign*(float)adc_code;
    voltage = voltage / (pow(2,15)-1);    //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
  }
  voltage = voltage * vref;           //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)


  return(voltage);
}