/*!
LTC2302: 12-Bit, 1-Channel 500ksps SAR ADC with SPI Interface.

@verbatim

The LTC2302 is a single-channel 12-bit A/D converter with with serial I/O.
The part can be configured to operate on unipolar or bipolar modes. The
automatic sleep mode benefits power sensitive applications.

SPI DATA FORMAT (MSB First):

            Byte #1                           Byte #2
Data In  :   X  OS   X   X  UNI  X    X   X    X   X   X   X   X   X   X   X
Data Out :  D15 D14 D13 D12 D11 D10  D9  D8   D7  D6  D5  D4  D3  D2  D1  D0

OS   : ODD/Sign Bit
UNI  : Unipolar/Bipolar Bit
Dx   : Data Bits
X    : Don't care

@endverbatim

http://www.linear.com/product/LTC2302

http://www.linear.com/product/LTC2302#demoboards


Copyright 2018(c) Analog Devices, Inc.

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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 LTC2302 LTC2302: 12-Bit, 1-Channel 500ksps SAR ADC with SPI Interface.
//! @}

/*! @file
    @ingroup LTC2302
    Library for LTC2302: 12-Bit, 1-Channel 500ksps SAR ADC with SPI Interface.
*/

#include "LT_SPI.h"
#include <SPI.h>
#include "LTC2302.h"

// Reads the ADC  and returns 16-bit data
void LTC2302_read(uint8_t cs, uint16_t adc_command, uint16_t *adc_code)
{
  spi_transfer_word(cs, (uint16_t)(adc_command), adc_code);
  spi_transfer_word(cs, (uint16_t)(adc_command), adc_code); // Throws out last reading and starts a new connection
}

// Calculates the LTC2302 input voltage given the data, range, and unipolar/bipolar status.
float LTC2302_code_to_voltage(uint16_t adc_code, float vref, uint8_t uni_bipolar)
{
  float voltage;
  float sign = 1;

  if (uni_bipolar == LTC2302_UNIPOLAR)
  {
    voltage = (float)adc_code;
    voltage = vref * voltage / (4095);          //! This calculates the actual voltage at the input (in volts)
  }
  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 = vref * voltage / 2047;           //! This calculates the actual voltage at the input (in volts)
  }

  return(voltage);
}