/*!
LTC1867: 16-bit 8-channel 200ksps ADC

@verbatim

The LTC1863/LTC1867 are pin-compatible, 8-channel 12-/16-bit A/D converters
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 LTC1867's DC performance is outstanding with a +/-2LSB INL specification and
no missing codes over temperature. The signal-to-noise ratio (SNR) for the
LTC1867 is typically 89dB, with the internal reference.

SPI DATA FORMAT (MSB First):

            Byte #1                           Byte #2
Data Out :  D15 D14 D13 D12 D11 D10 D9  D8    D7  D6  D5  D4  D3  D2  D1  D0
Data In  :  SD  OS  S1  S0  COM UNI SLP X     X   X   X   X   X   X   X   X

SD   : Single/Differential Bit
OS   : ODD/Sign Bit
Sx   : Address Select Bit
COM  : CH7/COM Configuration Bit
UNI  : Unipolar/Bipolar Bit
SLP  : Sleep Mode Bit
Dx   : Data Bits
X    : Don't care


Example Code:

Read Channel 0 in Single-Ended Unipolar mode when input is with respect to GND

    adc_command = LTC1867_CH0 | LTC1867_UNIPOLAR_MODE;  // Build ADC command for channel 0
    LTC1867_read(LTC1867_CS, adc_command, &adc_code);   // Throws out last reading
    LTC1867_read(LTC1867_CS, adc_command, &adc_code);   // Obtains the current reading and stores to adc_code variable

    // Convert adc_code to voltage
    adc_voltage = LTC1867_unipolar_code_to_voltage(adc_code, LTC1867_lsb, LTC1867_offset_unipolar_code);

@endverbatim

http://www.linear.com/product/LTC1867

http://www.linear.com/product/LTC1867#demoboards


Copyright 2018(c) Analog Devices, Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
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   notice, this list of conditions and the following disclaimer.
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   notice, this list of conditions and the following disclaimer in
   the documentation and/or other materials provided with the
   distribution.
 - Neither the name of Analog Devices, Inc. nor the names of its
   contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.
 - 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
   patent holders to use this software.
 - Use of the software either in source or binary form, must be run
   on or directly connected to an Analog Devices Inc. component.

THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
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*/

/*! @file
    @ingroup LTC1867
    Header for LTC1867: 16-bit 8-channel 200ksps ADC
*/

#ifndef LTC1867_H
#define LTC1867_H

#include <SPI.h>

//! Define the SPI CS pin
#ifndef LTC1867_CS
#define LTC1867_CS QUIKEVAL_CS
#endif

//! @name LTC1867 Single-Ended Channel Addresses, COM=GND
//! @{
// Single-Ended Channel Address When CH7/COM Pin Is used As CH7
#define LTC1867_CH0             0x80
#define LTC1867_CH1             0xC0
#define LTC1867_CH2             0x90
#define LTC1867_CH3             0xD0
#define LTC1867_CH4             0xA0
#define LTC1867_CH5             0xE0
#define LTC1867_CH6             0xB0
#define LTC1867_CH7             0xF0
//!@}

//! @name LTC1867 Differential Channel Addresses
//! @{
// Differential Channel Address When CH7/COM Pin Is Used As CH7
#define LTC1867_P0_N1           0x00
#define LTC1867_P1_N0           0x40

#define LTC1867_P2_N3           0x10
#define LTC1867_P3_N2           0x50

#define LTC1867_P4_N5           0x20
#define LTC1867_P5_N4           0x60

#define LTC1867_P6_N7           0x30
#define LTC1867_P7_N6           0x70
//!@}

//! @name LTC1867 Single-Ended Channel Addresses, COM=CH7
//! @{
// Channel Address When CH7/COM Pin Is Used As Common
#define LTC1867_CH0_7COM        0x88
#define LTC1867_CH1_7COM        0xC8
#define LTC1867_CH2_7COM        0x98
#define LTC1867_CH3_7COM        0xD8
#define LTC1867_CH4_7COM        0xA8
#define LTC1867_CH5_7COM        0xE8
#define LTC1867_CH6_7COM        0xB8
//!@}

//! @name LTC1867 Sleep / Unipolar/Bipolar config bits
//! @{
// Sleep Mode Command
#define LTC1867_SLEEP_MODE      0x02
#define LTC1867_EXIT_SLEEP_MODE 0x00
#define LTC1867_UNIPOLAR_MODE   0x04  // Bitwise OR with channel commands for unipolar mode
#define LTC1867_BIPOLAR_MODE    0x00
//!@}

/*
  Example command
  adc_command = LTC1867_P0_N1;                             // Differential Bipolar Mode with CH0 as positive and CH1 as negative.
  adc_command = LTC1867_P0_N1 | LTC1867_UNIPOLAR_MODE;     // Differential Unipolar Mode with CH0 as positive and CH1 as negative.
 */

//! Reads the ADC and returns 16-bit data
//! @return void
void LTC1867_read(uint8_t cs,           //!< Chip Select Pin
                  uint8_t adc_command,  //!< Channel address, config bits ORed together
                  uint16_t *adc_code    //!< Returns code read from ADC (from previous conversion)
                 );


//! Calculates the LTC1867 input's unipolar voltage given the binary data and lsb weight.
//! @return Floating point voltage
float LTC1867_unipolar_code_to_voltage(uint16_t adc_code,                   //!< Raw ADC code
                                       float LTC1867_lsb,                   //!< LSB value (volts)
                                       int32_t LTC1867_offset_unipolar_code //!< Offset code
                                      );

//! Calculates the LTC1867 input's bipolar voltage given the two's compliment data and lsb weight
//! @return  Floating point voltage
float LTC1867_bipolar_code_to_voltage(uint16_t adc_code,                   //!< Raw ADC code
                                      float LTC1867_lsb,                   //!< LSB value (volts)
                                      int32_t LTC1867_offset_bipolar_code  //!< Offset code
                                     );

//! Calibrate the offset and LSB voltage given two measured offset codes, and a full-scale voltage with the corresponding code.
//! @return Void
void LTC1867_cal_voltage(uint16_t zero_unipolar_code,                      //!< Code from a unipolar zero reading
                         uint16_t zero_bipolar_code,                       //!< Code from a bipolar zero reading
                         uint16_t fs_code,                                 //!< full-scale code
                         float zero_voltage,                               //!< Measured zero voltage
                         float fs_voltage,                                 //!< Measured full-scale voltage
                         float *LTC1867_lsb,                               //!< Return LSB value (volts)
                         int32_t *LTC1867_offset_unipolar_code,            //!< Return Unipolar Offset code, in floating point
                         int32_t *LTC1867_offset_bipolar_code              //!< Return Bipolar Offset code, in floating point
                        );

#endif  //  LTC1867_H