Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

Linear Technology DC1678A Demonstration Board. More...

Detailed Description

Linear Technology DC1678A Demonstration Board.

LTC2654: Quad SPI 16-/12-Bit Rail-to-Rail DACs with 10ppm/C Max Reference.

NOTES
  Setup:
   Set the terminal baud rate to 115200 and select the newline terminator.
   The program displays calculated voltages which are based on the voltage
   of the reference used, be it internal or external. A precision voltmeter
   is needed to verify the actual measured voltages against the calculated
   voltage displayed. If an external reference is used, a precision voltage
   source is required to apply the external reference voltage. A
   precision voltmeter is also required to measure the external reference
   voltage. No external power supply is required. Any assembly option
   may be used: DC1678A-A, DC1678A-B, DC1678A-C, DC1678A-D.


  Explanation of Commands:
   1- Select DAC: Select one of four DACs to test : A, B, C, D.

   2- Write to DAC input register: Value is stored in the DAC for updating
      later, allowing multiple channels to be updated at once, either
      through a software "Update All" command or by asserting the LDAC# pin.
      User will be prompted to enter either a code in hex or decimal, or a
      voltage. If a voltage is entered, a code will be calculated based on
      the active scaling and reference parameters - ideal values if no
      calibration was ever stored.

   3- Write and Update: Similar to item 1, but DAC is updated immediately.

   4- Update DAC: Copies the value from the input register into the DAC
      Register. Note that a "write and update" command writes the code to
      BOTH the input register and DAC register, so subsequent "update"
      commands will simply re-copy the same data (no change in output.)

   5- Power Down DAC: Disable DAC output. Power supply current is reduced.
      DAC code present in DAC registers at time of shutdown are preserved.

   6- Set reference mode, either internal or external: Selecting external
      mode prompts for the external reference voltage, which is used directly
      if no individual DAC calibration is stored. The selection and entered
      voltage are stored to EEPROM so it is persistent across reset / power cycles.

   7- Calibrate DAC: Use a precision voltmeter to obtain and enter VOUT
      readings taken with different DAC codes. Set reference mode FIRST,
      as values are stored separately for internal and external reference
      mode. Entries are used to calculate the closest code to send to the
      DAC to achieve an entered voltage.

   8- Enable / Disable calibration: Switch between stored calibration
      values and defaults. Calibration parameters are stored separately for
      internal and external reference modes. Ideal calibration will be used
      if the calibration parameter valid key is not set.

USER INPUT DATA FORMAT:
 decimal : 1024
 hex     : 0x400
 octal   : 02000  (leading 0 "zero")
 binary  : B10000000000
 float   : 1024.0

http://www.linear.com/product/LTC2654

http://www.linear.com/product/LTC2654#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:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • 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.
  • 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, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, 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.

Definition in file DC1678A.ino.

Go to the source code of this file.

Functions

static int8_t restore_calibration ()
 Read stored calibration parameters from nonvolatile EEPROM on demo board. More...
 
static void store_calibration ()
 Store measured calibration parameters to nonvolatile EEPROM on demo board. More...
 
static void print_title ()
 Prints the title block when program first starts. More...
 
static void print_prompt (int16_t selected_dac)
 Prints main menu. More...
 
static int16_t prompt_voltage_or_code ()
 Prompt user to enter a voltage or digital code to send to DAC. More...
 
static uint16_t get_voltage (float LTC2654_lsb, int16_t LTC2654_offset)
 Get voltage from user input, calculate DAC code based on lsb, offset. More...
 
static uint16_t get_code ()
 Get code to send to DAC directly, in decimal, hex, or binary. More...
 
static void calibrate_dac (uint8_t index)
 Calibrate the selected DAC using a voltmeter. More...
 
static void menu_1_select_dac (int16_t *selected_dac)
 Select which DAC to operate on. More...
 
static void menu_2_write_to_input_register (int16_t selected_dac)
 Write data to input register, but do not update DAC output. More...
 
static void menu_3_write_and_update_dac (int16_t selected_dac)
 Write data to DAC register (which updates output immediately) More...
 
static void menu_4_update_power_up_dac (int16_t selected_dac)
 Update DAC with data that is stored in input register, power up if sleeping. More...
 
static void menu_5_power_down_dac (int16_t selected_dac)
 Power down DAC. More...
 
static void menu_6_set_reference_mode (void)
 Set reference mode and store to EEPROM. More...
 
static void menu_7_calibrate_dacs ()
 Calibrate all DACs by measuring two known outputs. More...
 
static void menu_8_enable_calibration ()
 Enable / Disable calibration. More...
 
static void setup ()
 Initialize Linduino. More...
 
static void loop ()
 Repeats Linduino loop. More...
 

Macros

#define EEPROM_CAL_KEY_INT   0x5678
 Calibration associated with internal reference. More...
 
#define EEPROM_CAL_KEY_EXT   0x9ABC
 Calibration associated with external reference. More...
 
#define REF_INTERNAL   LTC2654_CMD_INTERNAL_REFERENCE
 Stored reference state is Internal. More...
 
#define REF_EXTERNAL   LTC2654_CMD_EXTERNAL_REFERENCE
 Stored reference state is External. More...
 
#define STORED_REF_STATE_BASE   EEPROM_CAL_STATUS_ADDRESS
 Base address of the stored reference state. More...
 
#define INT_CAL_VALID_BASE   STORED_REF_STATE_BASE + 2
 Base address of the "internal ref calibration valid" flag. More...
 
#define INT_CAL_PARAMS_BASE   INT_CAL_VALID_BASE + 2
 Base address of the internal ref calibration parameters. More...
 
#define EXT_CAL_VALID_BASE   INT_CAL_PARAMS_BASE + 32
 Base address of the "external ref calibration valid" flag. More...
 
#define EXT_CAL_PARAMS_BASE   EXT_CAL_VALID_BASE + 2
 Base address of the external ref calibration parameters. More...
 
#define EXT_REF_V_BASE   EXT_CAL_PARAMS_BASE + 32
 Base address of the stored external reference voltage. More...
 

Enumerations

enum  { PROMPT_VOLTAGE = 0, PROMPT_CODE = 1 }
 Used to keep track to print voltage or print code. More...
 

Variables

static uint8_t demo_board_connected
 Set to 1 if the board is connected. More...
 
static uint8_t shift_count = 0
 The data align shift count. More...
 
static uint8_t reference_mode
 Tells whether to set internal or external reference. More...
 
static float reference_voltage
 Reference voltage, either internal or external. More...
 
static int16_t LTC2654_offset [5]
 DAC offset - index 4 for "all DACs". More...
 
static float LTC2654_lsb [5]
 The LTC2654 lsb - index 4 for "all DACs". More...
 
const uint8_t address_map [5] = {LTC2654_DAC_A, LTC2654_DAC_B, LTC2654_DAC_C, LTC2654_DAC_D, LTC2654_DAC_ALL}
 Lookup table for DAC address. More...
 

Function Documentation

◆ calibrate_dac()

static void calibrate_dac ( uint8_t  index)
static

Calibrate the selected DAC using a voltmeter.

The routine does a linear curve fit given two data points.

Definition at line 602 of file DC1678A.ino.

◆ get_code()

static uint16_t get_code ( )
static

Get code to send to DAC directly, in decimal, hex, or binary.

Returns
code from user

Definition at line 540 of file DC1678A.ino.

◆ get_voltage()

static uint16_t get_voltage ( float  LTC2654_lsb,
int16_t  LTC2654_offset 
)
static

Get voltage from user input, calculate DAC code based on lsb, offset.

Returns
the DAC code

Definition at line 526 of file DC1678A.ino.

◆ loop()

static void loop ( void  )
static

Repeats Linduino loop.

Definition at line 197 of file DC1678A.ino.

◆ menu_1_select_dac()

static void menu_1_select_dac ( int16_t *  selected_dac)
static

Select which DAC to operate on.

Definition at line 251 of file DC1678A.ino.

◆ menu_2_write_to_input_register()

static void menu_2_write_to_input_register ( int16_t  selected_dac)
static

Write data to input register, but do not update DAC output.

Definition at line 263 of file DC1678A.ino.

◆ menu_3_write_and_update_dac()

static void menu_3_write_and_update_dac ( int16_t  selected_dac)
static

Write data to DAC register (which updates output immediately)

Definition at line 276 of file DC1678A.ino.

◆ menu_4_update_power_up_dac()

static void menu_4_update_power_up_dac ( int16_t  selected_dac)
static

Update DAC with data that is stored in input register, power up if sleeping.

Definition at line 289 of file DC1678A.ino.

◆ menu_5_power_down_dac()

static void menu_5_power_down_dac ( int16_t  selected_dac)
static

Power down DAC.

Definition at line 296 of file DC1678A.ino.

◆ menu_6_set_reference_mode()

static void menu_6_set_reference_mode ( void  )
static

Set reference mode and store to EEPROM.

Definition at line 303 of file DC1678A.ino.

◆ menu_7_calibrate_dacs()

static void menu_7_calibrate_dacs ( )
static

Calibrate all DACs by measuring two known outputs.

Definition at line 327 of file DC1678A.ino.

◆ menu_8_enable_calibration()

static void menu_8_enable_calibration ( )
static

Enable / Disable calibration.

Use with caution - behavior is undefined if you enable calibration and an actual calibration cycle has not been performed.

Definition at line 340 of file DC1678A.ino.

◆ print_prompt()

static void print_prompt ( int16_t  selected_dac)
static

Prints main menu.

Definition at line 568 of file DC1678A.ino.

◆ print_title()

static void print_title ( void  )
static

Prints the title block when program first starts.

Definition at line 553 of file DC1678A.ino.

◆ prompt_voltage_or_code()

static int16_t prompt_voltage_or_code ( )
static

Prompt user to enter a voltage or digital code to send to DAC.

Returns
user input

Definition at line 510 of file DC1678A.ino.

◆ restore_calibration()

static int8_t restore_calibration ( )
static

Read stored calibration parameters from nonvolatile EEPROM on demo board.

Returns
Return 1 if successful, 0 if not

Definition at line 368 of file DC1678A.ino.

◆ setup()

static void setup ( void  )
static

Initialize Linduino.

Definition at line 179 of file DC1678A.ino.

◆ store_calibration()

static void store_calibration ( )
static

Store measured calibration parameters to nonvolatile EEPROM on demo board.

Definition at line 482 of file DC1678A.ino.

Macro Definition Documentation

◆ EEPROM_CAL_KEY_EXT

#define EEPROM_CAL_KEY_EXT   0x9ABC

Calibration associated with external reference.

Definition at line 120 of file DC1678A.ino.

◆ EEPROM_CAL_KEY_INT

#define EEPROM_CAL_KEY_INT   0x5678

Calibration associated with internal reference.

Definition at line 119 of file DC1678A.ino.

◆ EXT_CAL_PARAMS_BASE

#define EXT_CAL_PARAMS_BASE   EXT_CAL_VALID_BASE + 2

Base address of the external ref calibration parameters.

Definition at line 133 of file DC1678A.ino.

◆ EXT_CAL_VALID_BASE

#define EXT_CAL_VALID_BASE   INT_CAL_PARAMS_BASE + 32

Base address of the "external ref calibration valid" flag.

Definition at line 132 of file DC1678A.ino.

◆ EXT_REF_V_BASE

#define EXT_REF_V_BASE   EXT_CAL_PARAMS_BASE + 32

Base address of the stored external reference voltage.

Definition at line 134 of file DC1678A.ino.

◆ INT_CAL_PARAMS_BASE

#define INT_CAL_PARAMS_BASE   INT_CAL_VALID_BASE + 2

Base address of the internal ref calibration parameters.

Definition at line 131 of file DC1678A.ino.

◆ INT_CAL_VALID_BASE

#define INT_CAL_VALID_BASE   STORED_REF_STATE_BASE + 2

Base address of the "internal ref calibration valid" flag.

Definition at line 130 of file DC1678A.ino.

◆ REF_EXTERNAL

#define REF_EXTERNAL   LTC2654_CMD_EXTERNAL_REFERENCE

Stored reference state is External.

Definition at line 126 of file DC1678A.ino.

◆ REF_INTERNAL

#define REF_INTERNAL   LTC2654_CMD_INTERNAL_REFERENCE

Stored reference state is Internal.

Definition at line 125 of file DC1678A.ino.

◆ STORED_REF_STATE_BASE

#define STORED_REF_STATE_BASE   EEPROM_CAL_STATUS_ADDRESS

Base address of the stored reference state.

Definition at line 129 of file DC1678A.ino.

Enumeration Type Documentation

◆ anonymous enum

anonymous enum

Used to keep track to print voltage or print code.

Enumerator
PROMPT_VOLTAGE 

0

PROMPT_CODE 

1

Definition at line 172 of file DC1678A.ino.

Variable Documentation

◆ address_map

Lookup table for DAC address.

Allows the "All DACs" address to be indexed right after DAC D in loops. This technique is very useful for devices with non-monotonic channel addresses. Map entered option 0..2 to DAC address

Definition at line 169 of file DC1678A.ino.

◆ demo_board_connected

uint8_t demo_board_connected
static

Set to 1 if the board is connected.

Definition at line 156 of file DC1678A.ino.

◆ LTC2654_lsb

float LTC2654_lsb[5]
static

The LTC2654 lsb - index 4 for "all DACs".

Definition at line 163 of file DC1678A.ino.

◆ LTC2654_offset

int16_t LTC2654_offset[5]
static

DAC offset - index 4 for "all DACs".

Definition at line 162 of file DC1678A.ino.

◆ reference_mode

uint8_t reference_mode
static

Tells whether to set internal or external reference.

Definition at line 158 of file DC1678A.ino.

◆ reference_voltage

float reference_voltage
static

Reference voltage, either internal or external.

Definition at line 161 of file DC1678A.ino.

◆ shift_count

uint8_t shift_count = 0
static

The data align shift count.

For 16-bit=0, for 12-bits=4

Definition at line 157 of file DC1678A.ino.