/*!
LTC2376-20: 20-Bit, 250Ksps ADC
LTC2377-20: 20-Bit, 500Ksps ADC
LTC2378-20: 20-Bit, 1Msps ADC

@verbatim

The following parts (DUT) are pin-compatible, 20-bit A/D converters with serial I/O, and an internal reference:
LTC2376-20: 20-Bit, 250Ksps ADC
LTC2377-20: 20-Bit, 500Ksps ADC
LTC2378-20: 20-Bit, 1Msps ADC

The DUTs typically draw only 8.4 mA from a single 2.5V supply. The automatic nap and sleep modes benefit power sensitive applications.

The DUTs DC performance is outstanding with a +/-0.5 ppm INL specification and
no missing codes over temperature. The signal-to-noise ratio (SNR) for the LTC2378 is typically 104 dB, with the internal reference.

@endverbatim

http://www.linear.com/product/LTC2376-20
http://www.linear.com/product/LTC2377-20
http://www.linear.com/product/LTC2378-20

http://www.linear.com/product/LTC2376-20#demoboards
http://www.linear.com/product/LTC2377-20#demoboards
http://www.linear.com/product/LTC2378-20#demoboards


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*/

//! @ingroup Analog_to_Digital_Converters
//! @{
//! @defgroup LTC2378 LTC2378: 16/18/20-Bit 1Msps ADC
//! @}

/*! @file
    @ingroup LTC2378
    Library for LTC2378: 16/18/20-Bit 1Msps ADC
*/

#include <Arduino.h>
#include <stdint.h>
#include "Linduino.h"
#include "LT_SPI.h"
#include "LTC2378.h"
#include <SPI.h>


// Reads from a SPI LTC2378-XX device that has no configuration word and a 32 bit output word in 2's complement format.
void LTC2378_read(uint8_t cs, int32_t *ptr_adc_code)
{
  LT_union_int16_2bytes command;    // LTC2378 data and command
  command.LT_uint16 = 0;                // Set to zero, not necessary but avoids
  // random data in scope shots.

//Form a four byte object to hold four bytes of data
  LT_union_int32_4bytes data; //instantiate the union
  data.LT_byte[3] = 0;
  data.LT_byte[2] = 0;
  data.LT_byte[1] = 0;
  data.LT_byte[0] = 0;

  spi_transfer_block(cs,command.LT_byte,data.LT_byte,4);

  *ptr_adc_code = data.LT_int32;

  return;
}


// Calculates the voltage corresponding to an adc code in 2's complement, given the reference voltage (in volts)
float LTC2378_code_to_voltage(int32_t adc_code, uint8_t gain_compression, float vref)
{
  float voltage;

  if (gain_compression == 1)
    vref = 0.8*vref;

  voltage = (float)adc_code;
  voltage = voltage / (pow(2,31)-1);    //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
  voltage = voltage * vref + 0.1;           //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)

  return(voltage);
}