/*!
LTC2418: LTC2418 - 16-Channel 24-Bit No Latency Delta-Sigma ADC

@verbatim

The LTC2414/LTC2418 are 8-/16-channel (4-/8-differential) micropower 24-bit
delta-sigma analog-to-digital converters. They operate from 2.7V to 5.5V and
include an integrated oscillator, 2ppm INL and 0.2ppm RMS noise. They use
delta-sigma technology and provide single cycle settling time for multiplexed
applications. Through a single pin, the LTC2414/LTC2418 can be configured for
better than 110dB differential mode rejection at 50Hz or 60Hz +/-2%, or they can
be driven by an external oscillator for a user-defined rejection frequency. The
internal oscillator requires no external frequency setting components.

@endverbatim

http://www.linear.com/product/LTC2418

http://www.linear.com/product/LTC2418#demoboards


Copyright 2018(c) Analog Devices, Inc.

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 - The use of this software may or may not infringe the patent rights
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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 LTC2418 LTC2418: 16-Channel 24-Bit No Latency Delta-Sigma ADC
//! @}

/*! @file
    @ingroup LTC2418
    Library for LTC2418: 16-Channel 24-Bit No Latency Delta-Sigma ADC
*/

#include <stdint.h>
#include <Arduino.h>
#include "Linduino.h"
#include "LT_SPI.h"
#include "LTC2418.h"
#include <SPI.h>

int8_t LTC2418_EOC_timeout(uint8_t cs, uint16_t miso_timeout)
// Checks for EOC with a specified timeout
{
  uint16_t timer_count = 0;             // Timer count for MISO
  output_low(cs);                       //! 1) Pull CS low
  while (1)                             //! 2) Wait for SDO (MISO) to go low
  {
    if (input(MISO) == 0) break;        //! 3) If SDO is low, break loop
    if (timer_count++>miso_timeout)     // If timeout, return 1 (failure)
    {
      output_high(cs);                  // Pull CS high
      return(1);
    }
    else
      delay(1);
  }
  return(0);
}

void LTC2418_read(uint8_t cs, uint8_t adc_command, uint32_t *adc_code)
// Reads the LTC2418
{
  LT_union_int32_4bytes data, command;
  command.LT_byte[3] = adc_command;
  command.LT_byte[2] = 0;
  command.LT_byte[1] = 0;
  command.LT_byte[0] = 0;

  output_low(cs);                                                       //! 1) Pull CS low
  spi_transfer_block(cs, command.LT_byte, data.LT_byte, (uint8_t)4);    //! 2) Transfer 4 bytes
  output_high(cs);                                                      //! 3) Pull CS high
  *adc_code = data.LT_int32;
}

float LTC2418_code_to_voltage(int32_t adc_code, float LTC2418_lsb , int32_t LTC2418_offset_code)
// Calculates the LTC2418 input bipolar voltage
{
  float adc_voltage;
  adc_code = adc_code>>6;                                           //! 1) Bit-shift ADC code to the right 6 bits
  adc_code -= 8388608;                                              //! 2) Convert ADC code from offset binary to binary
  adc_voltage=((float)adc_code+LTC2418_offset_code)*(LTC2418_lsb);  //! 3) Calculate voltage from ADC code, lsb, offset.
  return(adc_voltage);
}

void LTC2418_cal_voltage(int32_t zero_code, int32_t fs_code, float zero_voltage, float fs_voltage, float *LTC2418_lsb , int32_t *LTC2418_offset_code)
// Calibrate the lsb
{
  zero_code = zero_code >> 6;   //! 1) Bit-shift zero code to the right 6 bits
  zero_code -= 8388608;         //! 2) Convert zero code from offset binary to binary
  fs_code = fs_code >> 6;       //! 3) Bit-shift full scale code to the right 6 bits
  fs_code -= 8388608;           //! 4) Convert full scale code from offset binary to binary

  float temp_offset;
  *LTC2418_lsb = (fs_voltage-zero_voltage)/((float)(fs_code - zero_code));                              //! 5) Calculate the LSB

  temp_offset = (zero_voltage/ *LTC2418_lsb) - zero_code;                                               //! 6) Calculate Unipolar offset
  temp_offset = (temp_offset > (floor(temp_offset) + 0.5)) ? ceil(temp_offset) : floor(temp_offset);    //! 7) Round
  *LTC2418_offset_code = (int32_t)temp_offset;                                                          //! 8) Cast as int32_t
}