Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Easy Drive Input Current Cancellation. More...

Detailed Description

LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Easy Drive Input Current Cancellation.

The LTC2492 is a 4-channel (2-differential) 24-bit No Latency Delta Sigma
TM ADC with Easy Drive technology. The patented sampling scheme eliminates
dynamic input current errors and the shortcomings of on-chip buffering
through automatic cancellation of differential input current. This allows
large external source impedances, and rail-to-rail input signals to be
directly digitized while maintaining exceptional DC accuracy.


SPI DATA FORMAT (MSB First):

            Byte #1                            Byte #2

Data Out :  !EOC DMY SIG D28 D27 D26 D25 D24   D23  D22  D21  D20  D19 D18 D17 D16
Data In  :  1    0   EN  SGL OS  A2  A1  A0    EN2  IM   FA   FB   SPD X   X   X

Byte #3                        Byte #4
D15 D14 D13 D12 D11 D10 D9 D8  D7 D6 D5 D4 *D3 *D2 *D1 *D0
X   X   X   X   X   X   X  X   X  X  X  X   X  X   X   X

!EOC : End of Conversion Bit (Active Low)
DMY  : Dummy Bit (Always 0)
SIG  : Sign Bit (1-data positive, 0-data negative)
Dx   : Data Bits
*Dx  : Data Bits Below lsb
EN   : Enable Bit (0-keep previous mode, 1-change mode)
SGL  : Enable Single-Ended Bit (0-differential, 1-single-ended)
OS   : ODD/Sign Bit
Ax   : Address Select Bit
IM   : Internal Temperature Sensor Bit(0-ADC , 1-Temperature Sensor)
Fx   : Frequency Rejection Bits
SPD  : Speed Mode Bit (0-1x, 1-2x)

FIMSPD  : Double Output Rate Select Bit (0-Normal rate, auto-calibration on, 2x rate, auto_calibration off)

Command Byte #1
1    0    EN   SGL  OS   S2   S1   S0   Comments
1    0    0    X    X    X    X    X    Keep Previous Mode
1    0    1    0    X    X    X    X    Differential Mode
1    0    1    1    X    X    X    X    Single-Ended Mode

Example Code:

Read Channel 0 in Single-Ended

    uint16_t miso_timeout = 1000;
    adc_command = LTC2492_CH0 | LTC2492_OSR_32768 | LTC2492_SPEED_2X;   // Build ADC command for channel 0
                                                                        // OSR = 32768*2 = 65536

    if(LTC2492_EOC_timeout(LTC2492_CS, miso_timeout))    // Check for EOC
        return;                                          // Exit if timeout is reached
    LTC2492_read(LTC2492_CS, adc_command, &adc_code);    // Throws out last reading

    if(LTC2492_EOC_timeout(LTC2492_CS, miso_timeout))    // Check for EOC
        return;                                          // Exit if timeout is reached
    LTC2492_read(LTC2492_CS, adc_command, &adc_code);    // Obtains the current reading and stores to adc_code variable

    // Convert adc_code to voltage
    adc_voltage = LTC2492_code_to_voltage(adc_code, LTC2492_lsb, LTC2492_offset_code);

http://www.linear.com/product/LTC2492

http://www.linear.com/product/LTC2492#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.

Header for LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Selectable Speed/Resolution

Definition in file LTC2492.h.

Go to the source code of this file.

Functions

int8_t LTC2492_EOC_timeout (uint8_t cs, uint16_t miso_timeout)
 Checks for EOC with a specified timeout. More...
 
void LTC2492_read (uint8_t cs, uint8_t adc_command_high, uint8_t adc_command_low, int32_t *adc_code)
 Reads from LTC2492. More...
 
float LTC2492_code_to_voltage (int32_t adc_code, float vref)
 Calculates the voltage corresponding to an adc code, given the reference (in volts) More...
 

Macros

#define LTC2492_CS   QUIKEVAL_CS
 Define the SPI CS pin. More...
 
Mode Configuration
#define LTC2492_KEEP_PREVIOUS_MODE   LTC24XX_HS_MULTI_KEEP_PREVIOUS_MODE
 
#define LTC2492_KEEP_PREVIOUS_SPEED_RESOLUTION   LTC24XX_HS_MULTI_KEEP_PREVIOUS_SPEED_RESOLUTION
 
#define LTC2492_SPEED_1X   LTC24XX_HS_MULTI_SPEED_1X
 
#define LTC2492_SPEED_2X   LTC24XX_HS_MULTI_SPEED_2X
 
#define LTC2492_INTERNAL_TEMP   LTC24XX_EZ_MULTI_PTAT
 
#define LTC2492_R50   LTC24XX_EZ_MULTI_R50
 
#define LTC2492_R60   LTC24XX_EZ_MULTI_R60
 
#define LTC2492_R50_R60   LTC24XX_EZ_MULTI_R55
 
Single-Ended Channels Configuration
#define LTC2492_CH0   LTC24XX_MULTI_CH_CH0
 
#define LTC2492_CH1   LTC24XX_MULTI_CH_CH1
 
#define LTC2492_CH2   LTC24XX_MULTI_CH_CH2
 
#define LTC2492_CH3   LTC24XX_MULTI_CH_CH3
 
Differential Channel Configuration
#define LTC2492_P0_N1   LTC24XX_MULTI_CH_P0_N1
 
#define LTC2492_P1_N0   LTC24XX_MULTI_CH_P1_N0
 
#define LTC2492_P2_N3   LTC24XX_MULTI_CH_P2_N3
 
#define LTC2492_P3_N2   LTC24XX_MULTI_CH_P3_N2
 

Function Documentation

◆ LTC2492_code_to_voltage()

float LTC2492_code_to_voltage ( int32_t  adc_code,
float  vref 
)

Calculates the voltage corresponding to an adc code, given the reference (in volts)

Returns
Returns voltage calculated from ADC code.
Parameters
adc_codeCode read from adc
vrefVRef (in volts)

Definition at line 84 of file LTC2492.cpp.

◆ LTC2492_EOC_timeout()

int8_t LTC2492_EOC_timeout ( uint8_t  cs,
uint16_t  miso_timeout 
)

Checks for EOC with a specified timeout.

Returns
Returns 0=successful, 1=unsuccessful (exceeded timeout)
Parameters
csChip Select pin
miso_timeoutTimeout (in milliseconds)

Definition at line 72 of file LTC2492.cpp.

◆ LTC2492_read()

void LTC2492_read ( uint8_t  cs,
uint8_t  adc_command_high,
uint8_t  adc_command_low,
int32_t *  adc_code 
)

Reads from LTC2492.

Parameters
csChip select
adc_command_highHigh byte command written to LTC2492
adc_command_lowLow byte command written to LTC2492
adc_code4 byte conversion code read from LTC2492

Definition at line 78 of file LTC2492.cpp.

Macro Definition Documentation

◆ LTC2492_CH0

#define LTC2492_CH0   LTC24XX_MULTI_CH_CH0

Definition at line 138 of file LTC2492.h.

◆ LTC2492_CH1

#define LTC2492_CH1   LTC24XX_MULTI_CH_CH1

Definition at line 139 of file LTC2492.h.

◆ LTC2492_CH2

#define LTC2492_CH2   LTC24XX_MULTI_CH_CH2

Definition at line 140 of file LTC2492.h.

◆ LTC2492_CH3

#define LTC2492_CH3   LTC24XX_MULTI_CH_CH3

Definition at line 141 of file LTC2492.h.

◆ LTC2492_CS

#define LTC2492_CS   QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 116 of file LTC2492.h.

◆ LTC2492_INTERNAL_TEMP

#define LTC2492_INTERNAL_TEMP   LTC24XX_EZ_MULTI_PTAT

Definition at line 126 of file LTC2492.h.

◆ LTC2492_KEEP_PREVIOUS_MODE

#define LTC2492_KEEP_PREVIOUS_MODE   LTC24XX_HS_MULTI_KEEP_PREVIOUS_MODE

Definition at line 122 of file LTC2492.h.

◆ LTC2492_KEEP_PREVIOUS_SPEED_RESOLUTION

#define LTC2492_KEEP_PREVIOUS_SPEED_RESOLUTION   LTC24XX_HS_MULTI_KEEP_PREVIOUS_SPEED_RESOLUTION

Definition at line 123 of file LTC2492.h.

◆ LTC2492_P0_N1

#define LTC2492_P0_N1   LTC24XX_MULTI_CH_P0_N1

Definition at line 146 of file LTC2492.h.

◆ LTC2492_P1_N0

#define LTC2492_P1_N0   LTC24XX_MULTI_CH_P1_N0

Definition at line 147 of file LTC2492.h.

◆ LTC2492_P2_N3

#define LTC2492_P2_N3   LTC24XX_MULTI_CH_P2_N3

Definition at line 149 of file LTC2492.h.

◆ LTC2492_P3_N2

#define LTC2492_P3_N2   LTC24XX_MULTI_CH_P3_N2

Definition at line 150 of file LTC2492.h.

◆ LTC2492_R50

#define LTC2492_R50   LTC24XX_EZ_MULTI_R50

Definition at line 129 of file LTC2492.h.

◆ LTC2492_R50_R60

#define LTC2492_R50_R60   LTC24XX_EZ_MULTI_R55

Definition at line 131 of file LTC2492.h.

◆ LTC2492_R60

#define LTC2492_R60   LTC24XX_EZ_MULTI_R60

Definition at line 130 of file LTC2492.h.

◆ LTC2492_SPEED_1X

#define LTC2492_SPEED_1X   LTC24XX_HS_MULTI_SPEED_1X

Definition at line 124 of file LTC2492.h.

◆ LTC2492_SPEED_2X

#define LTC2492_SPEED_2X   LTC24XX_HS_MULTI_SPEED_2X

Definition at line 125 of file LTC2492.h.