Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

Linear Technology DC1703A Demonstration Board. More...

Detailed Description

Linear Technology DC1703A Demonstration Board.

LTC2655: Quad I2C 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:
   DC1703A-A, DC1703A-B, DC1703A-C, DC1703A-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 refernce voltage, which is used directly if no
      individual DAC calibration is stored. The selection and entered volgage
      are stored to EEPROM so it is persisent 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/LTC2655

http://www.linear.com/product/LTC2655#demoboards

Copyright 2018(c) Analog Devices, Inc.

All rights reserved.

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Definition in file DC1703A.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 LTC2655_lsb, int16_t LTC2655_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 int8_t calibrate_dac (uint8_t index)
 Calibrate the selected DAC using a voltmeter. More...
 
static int8_t menu_1_select_dac (int16_t *selected_dac)
 Select which DAC to operate on. More...
 
static int8_t menu_2_write_to_input_register (int16_t selected_dac)
 Write data to input register, but do not update DAC output. More...
 
static int8_t menu_3_write_and_update_dac (int16_t selected_dac)
 Write data to DAC register (which updates output immediately) More...
 
static int8_t 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 int8_t menu_5_power_down_dac (int16_t selected_dac)
 Power down DAC. More...
 
static int8_t menu_6_set_reference_mode (void)
 Set reference mode and store to EEPROM. More...
 
static int8_t menu_7_calibrate_dacs ()
 Calibrate all DACs by measuring two known outputs. More...
 
static int8_t 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   LTC2655_CMD_INTERNAL_REFERENCE
 Stored reference state is Internal. More...
 
#define REF_EXTERNAL   LTC2655_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 LTC2655_offset [5]
 DAC offset - index 4 for "all DACs." If part is calibrated, then index 0 is stored to "all DACs.". More...
 
static float LTC2655_lsb [5]
 The LTC2655 lsb - index 4 for "all DACs." If part is calibrated, then index 0 is stored to "all DACs.". More...
 
const uint8_t address_map [5] = {LTC2655_DAC_A, LTC2655_DAC_B, LTC2655_DAC_C, LTC2655_DAC_D, LTC2655_DAC_ALL}
 Lookup table for DAC address. More...
 

Function Documentation

◆ calibrate_dac()

static int8_t calibrate_dac ( uint8_t  index)
static

Calibrate the selected DAC using a voltmeter.

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

Returns
ACK bit (0=acknowledge, 1=no acknowledge)

Definition at line 636 of file DC1703A.ino.

◆ get_code()

static uint16_t get_code ( )
static

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

Returns
DAC code

Definition at line 568 of file DC1703A.ino.

◆ get_voltage()

static uint16_t get_voltage ( float  LTC2655_lsb,
int16_t  LTC2655_offset 
)
static

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

Returns
voltage

Definition at line 554 of file DC1703A.ino.

◆ loop()

static void loop ( void  )
static

Repeats Linduino loop.

Definition at line 200 of file DC1703A.ino.

◆ menu_1_select_dac()

static int8_t menu_1_select_dac ( int16_t *  selected_dac)
static

Select which DAC to operate on.

Returns
0

Definition at line 258 of file DC1703A.ino.

◆ menu_2_write_to_input_register()

static int8_t menu_2_write_to_input_register ( int16_t  selected_dac)
static

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

Returns
ACK bit (0=acknowledge, 1=no acknowledge)

Definition at line 272 of file DC1703A.ino.

◆ menu_3_write_and_update_dac()

static int8_t menu_3_write_and_update_dac ( int16_t  selected_dac)
static

Write data to DAC register (which updates output immediately)

Returns
ACK bit (0=acknowledge, 1=no acknowledge)

Definition at line 288 of file DC1703A.ino.

◆ menu_4_update_power_up_dac()

static int8_t 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.

Returns
ACK bit (0=acknowledge, 1=no acknowledge)

Definition at line 304 of file DC1703A.ino.

◆ menu_5_power_down_dac()

static int8_t menu_5_power_down_dac ( int16_t  selected_dac)
static

Power down DAC.

Returns
ACK bit (0=acknowledge, 1=no acknowledge)

Definition at line 314 of file DC1703A.ino.

◆ menu_6_set_reference_mode()

static int8_t menu_6_set_reference_mode ( void  )
static

Set reference mode and store to EEPROM.

Returns
0

Definition at line 324 of file DC1703A.ino.

◆ menu_7_calibrate_dacs()

static int8_t menu_7_calibrate_dacs ( )
static

Calibrate all DACs by measuring two known outputs.

Returns
0

Definition at line 350 of file DC1703A.ino.

◆ menu_8_enable_calibration()

static int8_t 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.

Returns
0

Definition at line 365 of file DC1703A.ino.

◆ print_prompt()

static void print_prompt ( int16_t  selected_dac)
static

Prints main menu.

Definition at line 596 of file DC1703A.ino.

◆ print_title()

static void print_title ( void  )
static

Prints the title block when program first starts.

Definition at line 581 of file DC1703A.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
prompt type

Definition at line 538 of file DC1703A.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 394 of file DC1703A.ino.

◆ setup()

static void setup ( void  )
static

Initialize Linduino.

Definition at line 183 of file DC1703A.ino.

◆ store_calibration()

static void store_calibration ( )
static

Store measured calibration parameters to nonvolatile EEPROM on demo board.

Definition at line 510 of file DC1703A.ino.

Macro Definition Documentation

◆ EEPROM_CAL_KEY_EXT

#define EEPROM_CAL_KEY_EXT   0x9ABC

Calibration associated with external reference.

This value is stored in EEPROM_CAL address of QuikEval EEPROM to indicate that a calibration occurred using the external reference. Calibration associated with external reference. (Stored in EEPROM_CAL address of QuikEval EEPROM).

Definition at line 124 of file DC1703A.ino.

◆ EEPROM_CAL_KEY_INT

#define EEPROM_CAL_KEY_INT   0x5678

Calibration associated with internal reference.

This value is stored in EEPROM_CAL address of QuikEval EEPROM to indicate that a calibration occurred using the internal reference.

Definition at line 121 of file DC1703A.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 137 of file DC1703A.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 136 of file DC1703A.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 138 of file DC1703A.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 135 of file DC1703A.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 134 of file DC1703A.ino.

◆ REF_EXTERNAL

#define REF_EXTERNAL   LTC2655_CMD_EXTERNAL_REFERENCE

Stored reference state is External.

Definition at line 130 of file DC1703A.ino.

◆ REF_INTERNAL

#define REF_INTERNAL   LTC2655_CMD_INTERNAL_REFERENCE

Stored reference state is Internal.

Definition at line 129 of file DC1703A.ino.

◆ STORED_REF_STATE_BASE

#define STORED_REF_STATE_BASE   EEPROM_CAL_STATUS_ADDRESS

Base address of the stored reference state.

Definition at line 133 of file DC1703A.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 176 of file DC1703A.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 173 of file DC1703A.ino.

◆ demo_board_connected

uint8_t demo_board_connected
static

Set to 1 if the board is connected.

Definition at line 160 of file DC1703A.ino.

◆ LTC2655_lsb

float LTC2655_lsb[5]
static

The LTC2655 lsb - index 4 for "all DACs." If part is calibrated, then index 0 is stored to "all DACs.".

Definition at line 167 of file DC1703A.ino.

◆ LTC2655_offset

int16_t LTC2655_offset[5]
static

DAC offset - index 4 for "all DACs." If part is calibrated, then index 0 is stored to "all DACs.".

Definition at line 166 of file DC1703A.ino.

◆ reference_mode

uint8_t reference_mode
static

Tells whether to set internal or external reference.

Definition at line 162 of file DC1703A.ino.

◆ reference_voltage

float reference_voltage
static

Reference voltage, either internal or external.

Definition at line 165 of file DC1703A.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 161 of file DC1703A.ino.