LTC2380-24 - 24-Bit, 1.5Msps/2Msps, Low Power SAR ADC with Integrated Digital Filter

/*!
LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter

@verbatim


@endverbatim
http://www.linear.com/product/LTC2380-24

REVISION HISTORY
$Revision: 4437 $
$Date: 2015-12-01 08:26:42 -0800 (Tue, 01 Dec 2015) $

Copyright (c) 2013, Linear Technology Corp.(LTC)
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation are those
of the authors and should not be interpreted as representing official policies,
either expressed or implied, of Linear Technology Corp.

The Linear Technology Linduino is not affiliated with the official Arduino team.
However, the Linduino is only possible because of the Arduino team's commitment
to the open-source community.  Please, visit http://www.arduino.cc and
http://store.arduino.cc , and consider a purchase that will help fund their
ongoing work.
*/

/*! @file
    @ingroup LTC2380-24
*/

#include <stdint.h>
#include "Linduino.h"
#include "LT_SPI.h"
#include "UserInterface.h"
#include "LT_I2C.h"
#include <SPI.h>
#include "LTC2380_24.h"

#ifndef LTC2380_CNV
#define LTC2380_CNV QUIKEVAL_CS
#endif

// Function Declaration
void print_title();                                         // Print the title block
void print_prompt();
void menu_1_read_input();
void menu_2_select_gain_compression();
void configureCNV();

// Global variables
static uint8_t LTC2380_dgc = 0;         //!< Default set for no gain compression
float LTC2380_vref  = 10;
float voltage;

//! Initialize Linduino
void setup()
{
  quikeval_SPI_init();           // Configure the spi port for 4MHz SCK
  quikeval_SPI_connect();        // Connect SPI to main data port
  Serial.begin(115200);          // Initialize the serial port to the PC

  configureCNV();

  print_title();
  print_prompt();
}

//! Repeats Linduino loop
void loop()
{
  uint16_t user_command;
  if (Serial.available())
  {
    user_command = read_int();        // Read the user command
    if (user_command != 'm')
      Serial.println(user_command);   // Prints the user command to com port
    switch (user_command)
    {
      case 1:
        menu_1_read_input();
        break;
      case 2:
        menu_2_select_gain_compression();
        break;
      default:
        Serial.println("  Invalid Option");
        break;
    }
    Serial.println();
    print_prompt();
  }
}

//! Read Input voltage
//! @return void
void menu_1_read_input()
{
  int32_t adc_code;                           // The LTC2380 code
  float adc_voltage;
  int16_t cycles;

  LTC2380_read(&adc_code, &cycles);
  adc_voltage = LTC2380_code_to_voltage(adc_code, LTC2380_dgc, LTC2380_vref);    // Convert the received code to voltage

  Serial.print("\n24-bit decimal data: 0x ");
  Serial.println(adc_code & 0xFFFFFF, HEX);
  Serial.print("Voltage calculated: ");
  Serial.print(adc_voltage);
  Serial.println(" V");
  Serial.print("No:of averaging cycles: ");
  Serial.println(cycles + 1);
  Serial.println();
}

//! Select gain compression
//! @return void
void menu_2_select_gain_compression()
{
  uint8_t user_command;
  Serial.println(F("  0 = No Gain Compression"));
  Serial.println(F("  1 = Gain Compression"));
  Serial.print(F("  Enter a Command, based upon the position of jumper JP6: "));

  user_command = read_int();    // Read user input
  Serial.println(user_command);   // Prints the user command to com port
  switch (user_command)
  {
    case 0:
      Serial.println(F("  No Gain compression"));
      LTC2380_dgc = 0;
      break;
    case 1:
      Serial.println(F("  Gain compression"));
      LTC2380_dgc = 1;
      break;
    default:
      {
        Serial.println("  Invalid Option");
        return;
      }
      break;
  }
}

//! Prints main menu.
void print_prompt()
{
  Serial.println(F("*************************"));
  Serial.println(F("1-Read ADC Input"));
  Serial.println(F("2-Select No Gain Compression / Gain Compression (default is no compression)"));
  Serial.print(F("Enter a command:"));
}

//! Prints the title block when program first starts.
void print_title()
{
  Serial.println();
  Serial.println(F("*****************************************************************"));
  Serial.println(F("* DC2289A Demonstration Program                                 *"));
  Serial.println(F("*                                                               *"));
  Serial.println(F("* This program demonstrates how to read data                    *"));
  Serial.println(F("* from LTC2380-24 bit part.                                     *"));
  Serial.println(F("*                                                               *"));
  Serial.println(F("* Set the baud rate to 115200 and select the newline terminator.*"));
  Serial.println(F("*                                                               *"));
  Serial.println(F("*****************************************************************"));
}

//! Function to configure CNV pin as an output
void configureCNV()
{
  DDRB = DDRB | B00000100;       // Setting PB2 (CS) as output, connected to CNV pin.
}

/*!
LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter

@verbatim



@endverbatim

http://www.linear.com/product/LTC2380-24

REVISION HISTORY
$Revision: 4437 $
$Date: 2015-12-01 08:26:42 -0800 (Tue, 01 Dec 2015) $

Copyright (c) 2013, Linear Technology Corp.(LTC)
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation are those
of the authors and should not be interpreted as representing official policies,
either expressed or implied, of Linear Technology Corp.

The Linear Technology Linduino is not affiliated with the official Arduino team.
However, the Linduino is only possible because of the Arduino team's commitment
to the open-source community.  Please, visit http://www.arduino.cc and
http://store.arduino.cc , and consider a purchase that will help fund their
ongoing work.
*/

/*! @file
    @ingroup LTC2380-24
    Header for LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter
*/

#ifndef LTC2380_H
#define LTC2380_H

#include <SPI.h>

//! Define the SPI CS pin
#ifndef LTC2380_CS
#define LTC2380_CS QUIKEVAL_CS
#endif

//! @name LTC2380 Channel Address
//! @{
// Channel Address
#define LTC2380_ADDRESS             0x00
//!@}


//! Reads the LTC2380 and returns 32-bit data in 2's complement format
//! @return void
void LTC2380_read(int32_t *ptr_adc_code,    //!< Returns code read from ADC (from previous conversion)
                  int16_t *ptr_cycles
                 );


//! Calculates the LTC2380 input voltage given the binary data and lsb weight.
//! @return Floating point voltage
float LTC2380_code_to_voltage(int32_t adc_code,                   //!< Raw ADC code
                              uint8_t gain_compression,
                              float vref              //!< Reference voltage
                             );

#endif  //  LTC2380_H

/*!
LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter

@verbatim


@endverbatim

http://www.linear.com/product/LTC2380-24

REVISION HISTORY
$Revision: 4437 $
$Date: 2015-12-01 08:26:42 -0800 (Tue, 01 Dec 2015) $

Copyright (c) 2013, Linear Technology Corp.(LTC)
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation are those
of the authors and should not be interpreted as representing official policies,
either expressed or implied, of Linear Technology Corp.

The Linear Technology Linduino is not affiliated with the official Arduino team.
However, the Linduino is only possible because of the Arduino team's commitment
to the open-source community.  Please, visit http://www.arduino.cc and
http://store.arduino.cc , and consider a purchase that will help fund their
ongoing work.
*/

//! @defgroup LTC2380-24 LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter

/*! @file
    @ingroup LTC2380-24
    Library for LTC2380-24: Low Noise, High Speed, 24-Bit SAR ADC With Digital Filter
*/

#include <Arduino.h>
#include <stdint.h>
#include "Linduino.h"
#include "LT_SPI.h"
#include "LTC2380_24.h"
#include <SPI.h>
#include "UserInterface.h"

// Reads from a SPI LTC2380-XX device that has no configuration word and a 32 bit output word in 2's complement format.
void LTC2380_read(int32_t *ptr_adc_code, int16_t *ptr_cycles)
{
  int N;
  int negative;

  Serial.print("\nEnter the number of CNV pulses: ");
  while (Serial.available());
  N = read_int();
  while (N--)       // PB2 (CS) pin is connected to CNV pin.
  {
    PORTB |=  B00000100;  // Pull CNV pin high
    __asm__("nop\n\t");
    PORTB &=  B11111011;  // Pull CNV pin low
    __asm__("nop\n\t");
  }

  LT_union_int16_2bytes cycles;    // LTC2380 data and command
  cycles.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;

  data.LT_byte[2] = spi_read(0);
  data.LT_byte[1] = spi_read(0);
  data.LT_byte[0] = spi_read(0);
  cycles.LT_byte[1] = spi_read(0);
  cycles.LT_byte[0] = spi_read(0);

  negative = (data.LT_byte[2] & 0x80) != 0;
  if (negative)
  {
    data.LT_byte[3] = 0xFF;
  }
  *ptr_adc_code = data.LT_int32;
  *ptr_cycles = cycles.LT_int16;

  return;
}

// Calculates the voltage corresponding to an adc code in 2's complement, given the reference voltage (in volts)
float LTC2380_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(2,24)-1);    //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
  voltage = voltage * vref;           //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)

  return(voltage);
}