/*!
LTC2308: 12-Bit 8-Channel 200ksps ADC

@verbatim

The LTC2308 is an 8-channel 12-bit A/D converter with
serial I/O, and an internal reference. The ADCs typically draw only 1.3mA from a
single 5V supply. The 8-channel input multiplexer can be configured for either
single-ended or differential inputs and unipolar or bipolar conversions (or
combinations thereof). The automatic nap and sleep modes benefit power sensitive
applications.

The LTC2308's DC performance is outstanding with a +/-2LSB INL specification and
no missing codes over temperature. The signal-to-noise ratio (SNR) for the
LTC2308 is typically 89dB, with the internal reference.

@endverbatim

http://www.linear.com/product/LTC2308

http://www.linear.com/product/LTC2308#demoboards


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*/

//! @ingroup Analog_to_Digital_Converters
//! @{
//! @defgroup LTC2308 LTC2308: 12-Bit 8-Channel 200ksps ADC
//! @}

/*! @file
    @ingroup LTC2308
    Library for LTC2308: 12-Bit 8-Channel 200ksps ADC
*/

#include <Arduino.h>
#include <stdint.h>
#include "Linduino.h"
#include "LT_SPI.h"
#include "LTC2308.h"
#include <SPI.h>


// Reads the ADC  and returns 16-bit data
void LTC2308_read(uint8_t cs, uint8_t adc_command, uint16_t *adc_code)
{
  spi_transfer_word(cs, (uint16_t)(adc_command<<8), adc_code);
}


// Calculates the LTC2308 input voltage given the data, range, and unipolar/bipolar status.
float LTC2308_code_to_voltage(uint16_t adc_code, float vref, uint8_t uni_bipolar)
{
  float voltage;
  float sign = 1;

  if (uni_bipolar == LTC2308_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);
}