/*!
LTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10

@verbatim

The LTC2421/LTC2422 are 1- and 2-channel 2.7V to 5.5V micropower 20-bit analog-
to-digital converters with an integrated oscillator, 8ppm INL and 1.2ppm RMS
noise. These ultrasmall devices use delta-sigma technology and a new digital
filter architecture that settles in a single cycle. This eliminates the latency
found in conventional delta-sigma converters and simplifies multiplexed
applications. Through a single pin, the LTC2421/LTC2422 can be configured for
better than 110dB rejection at 50Hz or 60Hz +/-2%, or can be driven by an
external oscillator for a user defined rejection frequency in the range 1Hz to
120Hz. The internal oscillator requires no external frequency setting
components.

@endverbatim

http://www.linear.com/product/LTC2422

http://www.linear.com/product/LTC2422#demoboard


Copyright 2018(c) Analog Devices, Inc.

All rights reserved.

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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
   from the requirement that you obtain separate licenses from these
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 - Use of the software either in source or binary form, must be run
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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 LTC2422 LTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10
//! @}

/*! @file
    @ingroup LTC2422
    Library for LLTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10
*/

#include <stdint.h>
#include <Arduino.h>
#include "Linduino.h"
//#include "LT_I2C.h"
#include "LT_SPI.h"
#include "LTC2422.h"
#include <SPI.h>

uint8_t LTC2422_EOC_timeout(uint8_t cs, uint16_t miso_timeout)
// Checks for EOC with a specified timeout (ms)
{
  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);
  }
  output_high(cs);                      // Pull CS high
  return(0);
}

// Read ADC code from the LTC2422. Does not wait for end-of-conversion.
// To automatically wait for conversion to complete, use the LTC2422_EOC_timeout before this function..
void LTC2422_adc_read(uint8_t cs, uint8_t *adc_channel, int32_t *code)
{
  LT_union_int32_4bytes data, command;      // LTC2422 data

  command.LT_int32 = 0x00000000;

  spi_transfer_block(LTC2422_CS, command.LT_byte , data.LT_byte, (uint8_t)3);
  if (data.LT_byte[2] & 0x40) // Obtains Channel Number
  {
    *adc_channel = 1;
  }
  else
  {
    *adc_channel = 0;
  }
  data.LT_byte[2] &= 0x3F;                  // Clear channel bit here so code to voltage function doesn't have to.
  data.LT_byte[3] = 0x00;                   // Make sure MS Byte is zero, data is right-justified.
  *code = data.LT_int32;                    // Return data
}

// Calculates the voltage given the ADC code and lsb weight.
float LTC2422_code_to_voltage(int32_t adc_code, float LTC2422_lsb)
{
  float adc_voltage;
  adc_code -= 0x00200000;                         //! 1) Subtract offset
  adc_voltage=((float)adc_code)*LTC2422_lsb;      //! 2) Calculate voltage from ADC code and lsb
  return(adc_voltage);
}

// Calculates the lsb weight from the given reference voltage.
void LTC2422_calculate_lsb(float LTC2422_reference_voltage, float *LTC2422_lsb)
{
  *LTC2422_lsb = LTC2422_reference_voltage/(1048575);        //! 1) Calculate the LSB, ref_voltage /(2^20-1)
}