ADMX2001B SPI Interface

The SPI interface can be used instead of the UART interface to send commands for configuration and measurement from the host. The SPI interface pins on the ADMX2001B module are SCK, SDI, SDO, and CS (B14-B17); see ADMX2001B Pin Configuration and Function Descriptions for the full pinout. On the evaluation board (EVAL-ADMX2001EBZ) the SPI interface is available on the Arduino style pin headers (P6 pins 5-8) and on both PMOD headers. See EVAL-ADMX2001EBZ Terminal Description for more details.

There is an example program for the SDP-K1 microcontroller that implements some functions to communicate with the ADMX2001B over the SPI interface. That code is available here: MBED SPI library.

SPI Protocol & Timing

SPI Interface Timing:

Parameter	Min	Typical	Max	Unit	Description	Test Conditions / Comments
SCLK Frequency		20		MHz	SPI clock frequency
T1		2.4		μsec	SS falling edge to SCLK rising edge setup time
T2	45			nsec	SCLK cycle time
T3	22.5			nsec	SCLK low time
T4	22.5			nsec	SCLK high time
T5	22.5			nsec	Data setup time
T6	22.5			nsec	Data hold time
T7		17.5	20	nsec	SCLK falling edge to SDO valid
T8		1.8		μsec	SCLK falling edge to SS rising edge
T9	32			μsec	Minimum SS high time	With (MBED SPI library)
T10		5.9		usec	SCLK low time between bytes (byte-to-byte gap)

SPI Command Summary

SPI Command Mapping:

SPI Command	Name	Function
0x00	Status Read	Return Host SPI Status
0x01	Result Read	Return the command result value in the DATAR word
0x02	Clear Error	Discard all previous SPI commands, results and errors, clear done bits including easurement done and command done, return SPI interface to the ready state
0x03	Measurement Read	Return the result of the measurement
0x04	Calibrate	Executes calibration routine
0x05	Compensation	Executes compensation routine
0x06	Readcal	Read the calibration coefficients for different gain combinations
0x07	Reserved	Reserved
0x08	Storecal	Write individual calibration coefficients
0x09	Resetcal	Reset calibration coefficients
0x0C	Rdcomp	Read compensation coefficients
0x0D	Storecomp	Write individual compensation coefficients
0x0F	Measure (z)	Perform the requested measurement(s) and return the value(s) in the result FIFO
0x10	Erase calibration	Erase the calibration coefficients stored in the flash memory (1.2.0 only)
0x11	Readsweep	Read sweep points for the measured values
0x12	Reset	Reset the device
0x13	Reserved	Reserved
0x14	Reserved	Reserved
0x15	Reserved	Reserved
0x16	Reserved	Reserved
0x17	Initiate	Initiate the measurement
0x18	Trigger	Provide software trigger for measurement
0x19	Reserved	Reserved
0x1A	Abort	Abort the measurement
0x1B	Calibration commit	Commit the calibration coefficients to the flash
0x1C	Set password	Update the password for committing calibration coefficients

Configure Parameters:

SPI Command	Name	Function
0x23	Frequency	Set the DDS frequency to N Hz where N is an IEEE-754 single precision floating point value
0x24	Reserved	Reserved
0x25	Magnitude	Set the test signal magnitude to N volts, where N is an IEEE-754 single precision floating point
0x26	Offset	Set the test signal’s DC bias to N volts, where N is an IEEE-754 single precision floating point
0x27	Reserved	Reserved
0x28	Voltage gain (CH0)	Set the voltage gain (0 = 1, 1 = 2, 2 = 4, 3 = 8)
0x29	Current gain (CH1)	Set the current gain (0 = -96.154, 1 =- 961.54, 2 = -9615.4, 3 = -96154.0)
0x2A	Average	Set the measurement loop to run N loops where N is an unsigned integer
0x2B	Mdelay	Set the measurement delay between measurements selected by the ‘count’ command to N msec, where N is an IEEE-754 single precision floating point value
0x2C	Tdelay	Set the trigger delay between measurement cycles selected by the ‘tcount’ command to N msec, where N is an IEEE-754 single precision floating point value
0x2D	Tcount	Set the trigger count to N where N is an unsigned integer
0x30	Sweep start	Set the sweep start frequency/magnitude/offset
0x31	Sweep end	Set the sweep end frequency/magnitude/offset
0x32	Sweep type	Set the sweep type to off/frequency/magnitude/offset
0x33	Sweep scale	Set the sweep scale as linear/log
0x34	Reserved	Reserved
0x38	Reserved	Reserved
0x39	Reserved	Reserved
0x3B	Temperature unit	Set the temperature unit as Celsius or Fahrenheit
0x3C	Reserved	Reserved
0x3D	Reserved	Reserved
0x41	Display mode	Set the measurement model output format
0x42	Sample count	Set the sample count for impedance/admittance measurements to N where N is an unsigned integer
0x43	Correction mode	Set calibration/compensation on or off
0x44	Error check	Set ADC/FPGA FIFO error checking on or off
0x45	DC mode	Enable or disable DC mode (must set offset instead of magnitude)
0x46	Autorange	Enable or disable autorange functionality
0x47	Reserved	Reserved
0x48	Reserved	Reserved
0x49	Reserved	Reserved
0x4A	Trigger mode	Set trigger mode to internal or external trigger
0x4F	Reserved	Reserved
0x50	Reserved	Reserved
0x51	Self-test	Run self-test
0x52	Reserved	Reserved
0x53	Reserved	Reserved
0x56	GPIO control	Set the digital output pins

Read Parameters:

SPI Command	Name	Function
0x8E	Temperature	Read the current module temperature, value returned is an IEEE-754 single precision floating point in degrees Celsius or Fahrenheit
0x15	Version	Read the module FW version: returns 32 bits, to be interpreted bytewise: [Major Version : Minor Version : Patch : Build Number]
0xA3	Frequency	Read the DDS frequency in Hz
0xA4	Reserved	Reserved
0xA5	Magnitude	Read the DDS magnitude
0xA6	Offset	Read the DC bias voltage
0xA7	Reserved	Reserved
0xA8	Voltage gain	Read the voltage gain setting
0xA9	Current gain	Read the current gain setting
0xAA	Average	Read measurement average count
0xAB	Mdelay	Read measurement delay
0xAC	Tdelay	Read trigger delay
0xAD	Tcount	Read the trigger count
0xB0	Sweep start	Read sweep start frequency/magnitude/offset
0xB1	Sweep end	Read sweep end frequency/magnitude/offset
0xB2	Sweep scale	Read sweep scale as linear/log
0xB4	Reserved	Reserved
0xB8	Reserved	Reserved
0xB9	Reserved	Reserved
0xBB	Temperature unit	Read temperature unit (Celsius or Fahrenheit)
0xBC	Reserved	Reserved
0xBD	Reserved	Reserved
0xC1	Display mode	Read the measurement model output format
0xC2	Sample count	Read the sample count value
0xC3	Reserved	Reserved
0xC4	Error check	Read whether ADC/FPGA FIFO error checking is on or off
0xC5	DC mode	Read whether DC mode is on or off
0xC6	Autorange	Read whether autoranging is on or off
0xC7	Reserved	Reserved
0xC8	Reserved	Reserved
0xC9	Reserved	Reserved
0xCA	Trigger mode	Read whether trigger mode is set to external or internal
0xCD	State	Read whether the state is in Idle or Wait for Trigger
0xCF	Reserved	Reserved
0xD0	Reserved	Reserved
0xD1	Self-test	Read self-test status
0xD2	Unique ID	Read the device unique ID
0xD3	Warning	Read warning status

Output Format Options:

Data	Format	Description
0	[Cs, Rs]	Capacitance and equivalent series resistance
1	[Cs ,D]	Equivalent series capacitance and dissipation factor
2	[Cs, Q]	Equivalent series capacitance and quality factor
3	[Ls, Rs]	Inductance and equivalent series resistance
4	[Ls ,D]	Equivalent series inductance and dissipation factor
5	[Ls, Q]	Equivalent series inductance and quality factor
6	[R, X]	Impedance in rectangular coordinates (default)
7	[Z, deg]	Impedance in magnitude and phase in degrees
8	[Z, rad]	Impedance in magnitude and phase in radians
9	[Cp, Rp]	Capacitance and equivalent parallel resistance
10	[Cp, D]	Equivalent parallel capacitance and dissipation factor
11	[Cp, Q]	Equivalent parallel capacitance and quality factor
12	[Lp, Rp]	Inductance and equivalent parallel resistance
13	[Lp, D]	Equivalent parallel Inductance and dissipation factor
14	[Lp, Q]	Equivalent parallel inductance and quality factor
15	[G, B]	Admittance in rectangular coordinates
16	[Y, deg]	Admittance in magnitude and phase in degrees
17	[Y, rad]	Admittance in magnitude and phase in radians
18		Reserved

Warnings:

Code	Warning
0x00	No warning
0x01	Reserved
0x02	Initializing calibration coefficient failed
0x04	Autorange disabled for sweep
0x08	Autorange failed
0x10	Sweep/measurement count is greater than supported
0x20	Magnitude is greater than 1 volt for AC autorange. Setting it to 1 V for AC autorange.
0x40	Offset is greater than 0 volts for AC autorange. Setting offset to 0 V for AC autorange.
0x80	Offset is greater than 1 volt for DC autorange. Setting offset to 1 V for DC autorange.
0x100	Offset is less than -1 volt for DC autorange. Setting offset to -1 V for DC autorange.

Errors:

Code	Error
0x0000	Success. No error.
0x0001	Command failure
0x0002	Reserved
0x0003	Invalid attribute
0x0004	Attribute out of range
0x0005	Invalid address for the command
0x0006	Uncommitted calibration coefficients (can be treated as warning)
0x0007	Invalid voltage/current gain
0x0008	Invalid display type for DC resistance mode
0x0009	Invalid sweep type for DC mode
0x000A	Invalid sweep range
0x000B	Invalid AC calibration coefficient type
0x000C	Reserved
0x000D	Invalid calibration type
0x000E	Invalid DC calibration coefficient type
0x000F	Calibration or compensation failed
0x0010	Invalid command for Wait for Trigger state
0x0020	Sweep start/end value can’t be zero for log scale
0x0040	Sweep start/end should have same sign for log scale
0x0080	Voltage ADC saturated
0x0100	Current ADC saturated
0x0200	Reserved

SPI Command Details

Single Parameter Write

Procedure for writing single parameter command:

• Do Frame Write with the respective command, address and data

• Poll the status register until the Done bit is set

Once the Done bit is set, the command has been processed. If any warnings or error occur, respective bit will be set

Single Parameter Read

Procedure for reading single parameter command:

• Do Frame Read with respective command, address and data

• Poll the status register until the Done bit is set

• Read result register if there is no error

Status Register Read (0x00)

The Status Register is a 32-bit read-only register and can be read using command 0x00. Register fields are shown in Status Register Field Descriptions.

Status Register:

Bit	31	30	29	28	27	26	25:16	15:0
Field	Measurement Done	Command Done	Error	Warning	FIFO Error	Reserved	Result FIFO Depth [9:0]	Result/Error Code

When any command is provided other than the Status, Result, and Measurement Read command, the Command Done bit will be cleared. After processing a given command, the Command Done bit will be set. The user must wait for this bit before providing the next command and/or to read data from The Result Register (0x01) or Measurement FIFO Register (0x03).

Status Register Field Descriptions:

Field	Description
Measurement Done	Will be set after measurement is complete
Command Done	Will be set after processing a command
Error	Will be set if there are any errors while processing the command
Warning	Will be set if one or more warnings occur during the command process. Should use the read warning command to fetch the warning code
FIFO Error	Will be set when overflow or underflow occurs. This error will be cleared only by using the Clear Error command
Result FIFO Depth [9:0]	Contains a count of 32-bit data streams that are present in the FIFO
Result/Error Code	Contains the Error Code when the Error bit is set

Do a Single Parameter Read with the command 0x00 to get the status.

Result Register Read (0x01)

Result register contains the processed output for few commands. Refer to the respective command’s section to know the data format and number of valid bits in the 32-bit field. Do a Single Parameter Read with 0x01 command to get the result.

Clear Error (0x02)

In order to clear SPI Measurement FIFO error, send the clear error command. It can also clear previous commands, measurement and command done bits, as well as retuls. It will return SPI interface to the ready state. Do a Single Parameter Write with 0x02 command and address & data field as zero to clear the error.

Measurement FIFO Read (0x03)

The Measurement FIFO contains either the measured value or sweep points. Refer to the respective command section to know the number of data and result data types stored in the FIFO. The Measurement FIFO should be read only when the Result FIFO Depth field in the status register is greater than 0. If the FIFO is read when it does not contain any data, FIFO Error will occur. Do a Single Parameter Read with 0x03 command to get the result.

Measure “Z” (0x0F)

Initiates the measurement immediately and stores the result in the Measurement FIFO. Result will be in two IEEE-754 Double precision format. Since only 32-bit data format is supported during a Single Parameter Read, 64 bit double data is split as two 32 bit data and written into the FIFO. Commands that will affect the measurement are: output format, trigger count, sample count, offset, frequency, magnitude, voltage/current gain, sweep, measure delay, trigger delay.

Note: Trigger mode command will be ignored by this command.

The figure below shows how results are stored into the FIFO. The number of 32-bit data stored into the FIFO for each measurement can be calculated using the following equation,

No. of data = (sample count * trigger count) * 4

Procedure:

• Configure the parameters (frequency, magnitude, etc…) with respective commands.

• Do Frame Write with z (0x0F) command.

• Poll status register until DONE and MEASURE DONE bit are set.

• Read the result from FIFO using MEASUREMENT FIFO READ command.

• Read sweep points using RDSWEEP command.

RDSWEEP (0x11)

After doing the measurement using z or trigger command, the sweep points can be read using this command. This command returns the count or frequency or magnitude or offset points as per the sweep type and count settings. Sweep points are in double precision format and are stored as two 32-bit data into the FIFO. These data can be read using the Measurement FIFO Read command. Number of points = (sample count * trigger count) Procedure:

• Do Frame Write with (0x11) in command and number of points in data field.

• Poll register until Done bit is set.

• Read the result from FIFO using the MEASUREMENT FIFO READ command.

Reset (0x12)

This command resets the entire device and sets the configuration parameters to its default value. Do a Single Parameter Write with reset command.

Initiate (0x17)

Initiate command initializes device for measurement and waits for the external/software trigger. Once external trigger is received, the measurement will be done automatically if external trigger is enabled and result will be populated into the FIFO. In “wait for trigger” state trigger, parameter read command, abort and reset commands are supported; other commands are not supported. Do a Single Parameter Write with the initiate command.

Trigger (0x18)

This command is treated as a software trigger for measuring the device under test. After measurement is completed, result will be stored into the FIFO. There are a few rules for using this command.

• Should be provided only after providing initiate command i.e. when the device is in “wait for trigger” state.

• Should be provided when software trigger is required. Should not be sent when external trigger is enabled.

• Device will accept trigger command for trigger count times. For example, if trigger count is 2 only two triggers will be accepted.

External Trigger Procedure

• Configure the device parameters. Enable external trigger with trigger mode command.

• Send initiate command.

• Provide external trigger and poll status register until Measurement Done bit is set.

• Read the result from FIFO. Refer to Measure Command to know how the data is stored in the FIFO. If required, read sweep points as well.

• Repeat steps 3 and 4 for tcount times.

Software Trigger Procedure

• Configure the device parameters. Enable/Disable external trigger with trigger mode command.

• Send initiate command.

• Send trigger command and poll status register until Measurement Done bit is set.

• Read the result from FIFO. Refer to Measure command to know how the data is stored in the FIFO. If required, read sweep points as well.

• Repeat steps 3 and 4 for tcount times.

Abort (0x1A)

The abort command resets the state machine and sets it to “idle” state. It doesn’t change the configuration parameters. Do a Single Parameter Write with the abort command.

Frequency (0x23, 0xA3)

Frequency at which measurement should happen. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Frequency Command Format:

Description	Value
Default	1000 (unit:Hz)
Write command	0x23
Read command	0xA3
Address	0x0
Data range	0 Hz, 0.2 Hz to 10000000 Hz
Data type	IEEE-754 Single precision floating point

Magnitude (0x25, 0xA5)

Magnitude at which measurement should happen. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Magnitude Command Format:

Description	Value
Default	1 V
Write command	0x25
Read command	0xA5
Address	0x0
Data range	0.13 to 2.25 V
Data type	IEEE-754 Single precision floating point

Offset (0x26, 0xA6)

Offset voltage at which measurement should happen. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Offset Command Format:

Description	Value
Default	0 V
Write command	0x26
Read command	0xA6
Address	0x0
Data range	-2.5 V to 2.5 V
Data type	IEEE-754 Single precision floating point

Voltage Gain (0x28, 0xA8)

Set or get the voltage gain factor (0 = 1, 1 = 2, 2 = 4, 3 = 8). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: This value will be ignored when auto range is enabled.

Voltage Gain Command Format:

Description	Value
Default	0
Write command	0x28
Read command	0xA8
Address	0x0
Data range	0 to 3
Data type	32-bit integer

Current Gain (0x29, 0xA9)

Set or get the current gain factor (0 = 96.154, 1 = 961.54, 2 = 9615.4, 3 = 96154.0). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: This value will be ignored when auto range is enabled.

Current Gain Command Format:

Description	Value
Default	1
Write command	0x29
Read command	0xA9
Address	0x0
Data range	0 to 3
Data type	32-bit integer

Average (0x2A, 0xAA)

Number of samples to average while taking measurement. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Average Command Format:

Description	Value
Default	1
Write command	0x2A
Read command	0xAA
Address	0x0
Data range	1 to 65536
Data type	32-bit integer

Measure Delay MDELAY (0x2B, 0xAB)

Delay (time to wait) before doing each measurement. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Measure Delay Command Format:

Description	Value
Default	1 ms
Write command	0x2B
Read command	0xAB
Address	0x0
Data range	0.0 to 65536.0
Data type	IEEE-754 Single precision floating point

Trigger Delay TDELAY (0x2C, 0xAC)

Delay (time to wait) after receiving each (internal/external) trigger. This delay is necessary for the AC output signal to get settle before doing the measurement. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Trigger Delay Command Format:

Description	Value
Default	4 ms
Write command	0x2C
Read command	0xAC
Address	0x0
Data range	0.0 to 65536.0
Data type	IEEE-754 Single precision floating point

Trigger Count TCOUNT (0x2D, 0xAD)

Number of time to trigger the sweep measurement. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: Only 256 measurement results can be stored in the measurement FIFO. If sample count * trigger count is greater than 256, readings will be lost.

Trigger Count Command Format:

Description	Value
Default	1
Write command	0x2D
Read command	0xAD
Address	0x0
Data range	1 to 65536
Data type	32-bit integer

Sweep Start (0x30, 0xB0)

Set or get the sweep start frequency or magnitude or offset. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Sweep Start Command Format:

Description	Value
Default	0
Write command	0x30
Read command	0xB0
Address	0x0
Data range	Frequency: 0.2 to 10000000 (unit: Hz) Magnitude: 0.13 to 2.25 (unit: V) Offset: -2.5 to +2.5 (unit: V)
Data type	IEEE-754 Single precision floating point

Sweep End (0x31, 0xB1)

Set or get the sweep end frequency or magnitude or offset. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Sweep End Command Format:

Description	Value
Default	1
Write command	0x31
Read command	0xB1
Address	0x0
Data range	Frequency: 0.2 to 10000000 (unit: Hz) Magnitude: 0.13 to 2.25 (unit: V) Offset: -2.5 to +2.5 (unit: V)
Data type	IEEE-754 Single precision floating point

Sweep Type (0x32, 0xB2)

Set or get the sweep type (0 = off, 1 = frequency, 2 = offset, 3 = magnitude). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Sweep Type Command Format:

Description	Value
Default	0
Write command	0x32
Read command	0xB2
Address	0x0
Data range	0 to 3
Data type	32-bit integer

Sweep Scale (0x33, 0xB3)

Set or get the sweep scale (0 = linear, 1 = logarithmic). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Sweep Scale Command Format:

Description	Value
Default	0
Write command	0x33
Read command	0xB3
Address	0x0
Data range	0 or 1
Data type	32-bit integer

Temperature Unit (0x3B, 0xBB)

Set or get the temperature unit (0 = Fahrenheit, 1 = Celsius). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Temperature Unit Command Format:

Description	Value
Default	1
Write command	0x3B
Read command	0xBB
Address	0x0
Data range	0 or 1
Data type	Boolean

Output Format (0x41, 0xC1)

Set or get the output format, formats listed in the table below. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Output Format Command Format:

Description	Value
Default	6
Write command	0x41
Read command	0xC1
Address	0x0
Data range	0 to 17
Data type	32-bit integer

Sample Count (0x42, 0xC2)

Set or get the number of readings to be taken in a sweep. To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: Only 256 measurement results can be stored in the measurement FIFO. If sample count * trigger count is greater than 256, readings will be lost.

Sample Count Command Format:

Description	Value
Default	1
Write command	0x42
Read command	0xC2
Address	0x0
Data range	1 to 32768
Data type	32-bit integer

Correction Mode (0x43, 0xC3)

Set or get the correction mode (0 = off, 1 = calibration, 2 = calibration + compensation). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: Compensation cannot be used without calibration being enabled. Calibration must be turned on before compensation can be turned on.

Correction Mode Command Format:

Description	Value
Default	1
Write command	0x43
Read command	0xC3
Address	0x0
Data range	0 to 2
Data type	32-bit integer

Error Check (0xC4, 0x0)

Set or get ADC saturation error checking (0 = disable, 1 = enable). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Error Check Command Format:

Description	Value
Default	0x44
Write command	0xC4
Read command	0x0
Address	0x0
Data range	0 or 1
Data type	Boolean

DC Mode (0x45, 0xC5)

Set or get DC mode (1 = disable, 0 = enable). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note: In order to do DC measurement, DC mode should be enabled (set parameter to 0) and frequency should be set to 0 Hz. Since the AC source is off in DC mode, the DC offset should be set to the desired value.

DC Mode Command Format:

Description	Value
Default	1 (disabled)
Write command	0x45
Read command	0xC5
Address	0x0
Data range	0 or 1
Data type	Boolean

Auto Range (0x46, 0xC6)

Set or get Auto ranging of voltage and current gain (0 = disable, 1 = enable). To configure or fetch data, do a Single Parameter Write or Single Parameter Read.

Note1: When auto range is enabled, voltage gain & current gain settings will be updated automatically.

Note2: Auto range will be disabled during calibration, compensation and when sweep type is “frequency or offset or magnitude”

Auto Range Command Format:

Description	Value
Default	1
Write command	0x46
Read command	0xC6
Address	0x0
Data range	0 or 1
Data type	Boolean

Trigger Mode (0x4A, 0xCA)

Set or get Trigger mode (0 = internal/software, 1 = external). To configure or fetch data, do a Single Parameter Write or Single Parameter Read. Note: This mode will be ignored during calibration, compensation and measure (Z) command.

Trigger Mode Command Format:

Description	Value
Default	0
Write command	0x4A
Read command	0xCA
Address	0x0
Data range	0 or 1
Data type	Boolean

State (0xCD)

This command reads the current state of the device. Value 0 means device is in idle state and 1 means device is in wait for trigger state. Do a Single Parameter Read to fetch the state.

State Machine Register Format:

Description	Value
Default	0
Read command	0xCD
Address	0x0
Data range	0 or 1
Data type	32-bit integer

Self-Test (0x51, 0xD1)

Self-test runs after powering on the device. Self-test (0x51) command initiates the self-test routine and returns pass or fail in the error code field in the status register. Self-test (0xD1) reads the self-test status code in result register. To initiate self-test, do Single Parameter Write and to fetch status code, do a Single Parameter Read.

Note: Before initiating self-test make sure test leads/test fixture is in the open configuration, otherwise the analog test will fail. The self-test does not need to pass on every boot for the board to function properly.

Self-Test Command Format:

Description	Value
Default	0
Run command	0x51
Read command	0xD1
Address	0x0
Data range	0 to 63
Data type	32-bit integer

Self-Test Status Code:

Bit	Value
0	ADC IC test failed
1	DAC IC test failed
2	Temperature IC test failed
3	Analog test failed
4	Unique ID test failed
5	EEPROM/Flash IC test failed

Unique ID (0xD2)

Unique device ID can be fetched can be using this command. Do a Single Parameter Read with the respective command and address. The unique ID is a 64-bit integer, but frame format is only 32-bit data, so it is split into multiple address.

Unique ID Register Format:

Description	Value
Default
Read command	0xD2
Address	0x0: lower 32-bit, 0x1: higher 32-bit
Data range	0 to 4294967295
Data type	32-bit integer

Warning Status (0xD3)

Warning status can be fetched using this command. Do a Single Parameter Read with this command. Refer to the list of warnings to know the description of the code.

Warning Status Register Format:

Description	Value
Default	0
Read command	0xD3
Address	0x0
Data range	0 to 65536
Data type	32-bit integer

Calibration Command Summary

The section below describes all calibration commands and utilities.

CAL (0x04) / COMP (0x05)

CAL/COMP command is used to perform open, short and load calibration/compensation. The Rt and Xt values for load calibration/compensation are sent in the data field as a 32-bit floating point. For running open/short/load calibration or open/short/load compensation commands the data field is redundant. The result register will contain the appropriate error code if the calibration or compensation fails. Open and short calibration/compensation must be performed before load calibration/compensation to proceed. Refer to the Calibration and Compensation Commands table for details about the address and data fields.

Open/Short/Load Calibration Command Mapping

Command	Address	Data range	Data type	Description
0x04	0	N/A	32-bit integer	Reserved
	1	N/A	32-bit integer	Run short circuit calibration
	2	N/A	32-bit integer	Run open circuit calibration
	3	N/A	32-bit integer	Run load calibration with configured Rt/Xt. Must have Rt/Xt configured before running load calibration.
	4	Rt as an IEEE-754 floating point	32-bit integer	Set Rt for load calibration
	5	Xt as an IEEE-754 floating point	32-bit integer	Set Xt for load calibration
	0xFF	N/A	32-bit integer	Run reload calibration. Will load the nearest frequency calibration coefficients from the nonvolatile memory and store them in the RAM

Note the last row has an address field 0xFF. This command/address combination is for a new command called reload calibration (starting in firmware 1.2.2). To run this command, the address filed needs to be set as 0xFF. The reload command will load the nearest frequency calibration coefficients from the nonvolatile memory and store them in the RAM. This is especially useful when user wants to read calibration coefficients taken at different frequencies (i.e. calibration over frequency). Say a new frequency is set, user will need to run reload calibration first, then perform CAL_READ (0x06) to load calibration coefficients at that specific frequency from FLASH to RAM. Otherwise, calibration coefficients successfully read at previous set frequency will be misread for the new frequency.

Open/Short/Load Compensation Command Mapping

Command	Address	Data range	Data type	Description
0x05	0	N/A	32-bit integer	Reserved
	1	N/A	32-bit integer	Run short circuit compensation
	2	N/A	32-bit integer	Run open circuit compensation
	3	N/A	32-bit integer	Run load compensation with configured Rt/Xt. Must have Rt/Xt configured before running load compensation.
	4	Rt as an IEEE-754 floating point	32-bit integer	Set Rt for load compensation
	5	Xt as an IEEE-754 floating point	32-bit integer	Set Xt for load compensation

CAL_COMMIT (0x1B)

CAL_COMMIT command is used to commit the calibration data to the flash after performing a password check. The password is written to the input password buffer as ASCII values of characters corresponding to the first 12 address’s locations or fields (with values in decimal). The address field directs information from the data field to various locations or initiates specific processes. The address location 12 is reserved for the Unix timestamp of the commit. Sending 0xFF in the address field will compare the password stored and commit the calibration data if the password matches the set password. In case the password is incorrect sending 0xFF will clear the input password buffer. Performing calibration or using the CAL_STORE to store calibration coefficients is needed before committing the calibration data. Refer to the Commit Calibration Commands table for details about the address and data fields.

Commit Calibration Command Mapping

Write Command	Address	Data range	Data type	Description
0x1B	0 1 2 … 10 11	26 upper and 26 lower case letters, 10 digits, and 33 special characters Space char (0x20) not allowed	ASCII value of Nth character of password, as indicated by address field value	Send char 0 of the password Send char 1 of the password Send char 2 of the password … Send char 10 of the password Send char 11 of the password
	12	-2147483648 to 2147483647	32-bit integer	Commit Timestamp, Unix epoch time in seconds since Jan 1, 1970 UTC
	0xFF	N/A	N/A	Compare set password with the stored password, commit calibration data if the password is correct

CAL_READ (0x06) / COMP_READ (0x0C)

The CAL_READ command is used to read the calibration coefficients and data by setting specific calibration address in the command’s address field. COMP_READ functions similarity, which reads the compensation coefficients and data by setting the corresponding compensation address in the command’s address field. The calibration and compensation data is polled from result register. The distinction between coefficients and data is that coefficients refer to the 12 AC coefficients (calibration and compensation) and 2 DC coefficients (calibration only), while data refers to status (open/short/load calibration or compensation), frequency and temperature. For more details refer to Read Calibration/Compensation Command Mapping Table. Such address is access bitwise as follows:

• The bit 3 to bit 0 of the address need to be set to the voltage and current gain for which the calibrations/compensation coefficients are to be read.

• The bit 8 to bit 4 of the address field are redundant.

• The bit 9 of the address can be used to toggle between two modes, calibration/compensation data read mode and calibration/compensation coefficients read mode. In case calibration/compensation coefficients read mode is used, the bit 14 is used to either read the MSB or the LSB of the 64-bit double valued calibration/compensation coefficient. The calibration/compensation coefficient is set by appropriately setting the bit 13 to bit 10. In case calibration/compensation data read mode is used, ignores bit 14 and can be used to read the calibration/compensation data in its respective formats.

To send CAL_READ/COMP_READ commands, user can build a compound address using bitwise to the left operation to construct each sub-filed based on 2-bit voltage gain, 2-bit current gain, 1-bit mode type, 4-bit coefficient type, and (if relevant) 1-bit coefficients LSB/MSB. After writing the address and getting a successful status, the result register will contain the MSB/LSB of the calibration coefficient or the requested calibration data. The same applies to compensation read too. Refer to the Calibration Commands and Compensation Commands table for details about the address and data fields.

Read Calibration Command Mapping

Read Command	Address	Data range	Data type	Description
0x06	Bit 14	0 or 1	1-bit address	Coefficients LSB/MSB is decided by bit 14 (for calibration coefficient read, will be invalid for calibration data read). 0 - LSB of double value 1 - MSB of double value
	Bit 13 to bit 10	For calibration coefficients refer to Table “Calibration/ Compensation Coefficients and Data Register Format”. For calibration data: - 0000 for AC calibration status - 0001 for AC calibration frequency - 0010 for AC calibration temperature	4-bit address	Calibration coefficient or calibration data to be read
	Bit 9	0 or 1	1-bit address	Flip between calibration coefficients/calibration data read mode 0 - Read calibration coefficients 1 - Read calibration data
	Bit 8 to bit 4	N/A	N/A	Redundant bits, can default to 0
	Bit 3 to bit 2	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Current gain of coefficients
	Bit 1 to bit 0	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Voltage gain of coefficients

Read Compensation Command Mapping

Read Command	Address	Data range	Data type	Description
0x0C	Bit 14	0 or 1	1-bit address	Coefficients LSB/MSB is decided by bit 14. 0 - LSB of double value 1 - MSB of double value
	Bit 13 to bit 10	For calibration coefficients refer to Table “Calibration/ Compensation Coefficients and Data Register Format”. For compensation data: - 0000 for AC compensation status - 0001 for AC compensation frequency - 0010 for AC compensation temperature	4-bit address	Compensation coefficient or compensation data to be read
	Bit 9	0 or 1	1-bit address	Flip between compensation coefficients/compensation data read mode 0 - Read compensation coefficients 1 - Read compensation data
	Bit 8 to bit 4	N/A	N/A	Redundant bits, can default to 0
	Bit 3 to bit 2	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Current gain of coefficients
	Bit 1 to bit 0	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Voltage gain of coefficients

When reading the coefficients, there may be instances where they don’t exist for the user-specified frequency and voltage/current gain settings. When implementing the command in SPI, users need to provide a set of default coefficients if the CAL_READ or COMP_READ command triggers an error flag (flag_ERROR). The default values commonly used by the ADMX2001 are as follows.

When reading calibration or compensation status (command 0x06 or 0x0C) by correctly accessing the address value 00001 for bit 13 to bit 9, following masks will return, each indicating a different type of calibration coefficients are received.

• 0x000F - indicates open calibration coefficients are received

• 0x00F0 – indicates short calibration coefficients are received

• 0x0F00 – indicates load calibration coefficients are received

Default Calibration/Compensation Coefficient Values

Calibration/Compensation Coefficients	Default values
Ro	1.00E+06
Xo	1.00E+06
Go	0
Bo	0
Rs	0
Xs	0
Gs	1.00E+06
Bs	1.00E+06
Rg	-1.00E+06
Xg	-1.00E+06
Gg	-1.00E+06
Bg	-1.00E+06
Rdg	1.00E+00
Rdo	0

Calibration/Compensation Coefficients and Data Register Format

Type	Address (Bit 13 to Bit 9)	Value returned in result register
AC coefficients, applicable to both calibration and compensation	0b00000	Ro
	0b00010	Xo
	0b00100	Go
	0b00110	Bo
	0b01000	Rs
	0b01010	Xs
	0b01100	Gs
	0b01110	Bs
	0b10000	Rg
	0b10010	Xg
	0b10100	Gg
	0b10110	Bg
AC calibration/ compensation data	0b00001	AC calibration status (32-bit integer)
	0b00011	AC calibration frequency (IEEE-754 Floating point)
	0b00101	AC calibration temperature (IEEE-754 Floating point)
	Below: only for CAL_READ, invalid addresses for COMP_READ
DC calibration coefficients	0b11000	Rdo
	0b11010	Rdg
DC calibration data	0b00111	DC calibration status (32 bit int)
	0b01001	DC calibration frequency (IEEE-754 Floating point)
	0b01011	DC calibration temperature (IEEE-754 Floating point)

RESETCAL (0x09)

CAL_RESET command is used to reset the calibration coefficients. To clear calibration coefficients for a particular voltage and current gain setting, specify the first 4 address bits to the gain values. To clear all calibration coefficients, the address can be set to 0xFF. For running calibration reset commands the data field is redundant. Refer to the Reset Calibration Commands table for details about the address and data fields.

Reset Calibration Command Mapping

Write Command	Address	Data range	Data type	Description
0x09	Bit 1 to bit 0	N/A	N/A	Voltage gain of coefficients
	Bit 3 to bit 2	N/A	N/A	Current gain of coefficients
	0xFF	N/A	N/A	Reset all calibration coefficients

CAL_ERASE (0x10)

CAL_ERASE command is used to permanently delete all saved calibration coefficient sets from the memory after performing a password check. When completed, it restores them to the default configurations. The password is written to the input password buffer as ASCII values of characters corresponding to the first 12 address’s locations or fields (with values in decimal). Sending 0xFF in the address field will compare it to the password stored and erase the calibration data if the password matches the set password, then initialize calibration coefficients to default configurations. In case the password is incorrect sending 0xFF will clear the input password buffer.

Erase Calibration Coefficients Command Mapping

Write Command	Address	Data range	Data type	Description
0x10	0 1 2 … 10 11	26 upper and 26 lower case letters, 10 digits, and 33 special characters Space char (0x20) not allowed	ASCII value of Nth character of password, as indicated by address field value	Send char 0 of the password Send char 1 of the password Send char 2 of the password … Send char 10 of the password Send char 11 of the password
	0xFF	N/A	N/A	Compare set password with the stored password, permanently erase calibration coefficients if the password is correct. Then restore calibration coefficients to default configurations.

SET_PASSWORD (0x1c)

SET_PASSWORD is used to set the commit password after performing a password check. The current password is written to the current password buffer as ASCII values of characters corresponding to the address locations 12-23. Upon completion, sending the address as 0xFE will have the current password buffer compared with the commit password. If it is a match, it enables setting the new password. The address locations 0-11 are reserved for writing the new password to the new password buffer. Each character of the new password is written in the same way as ASCII values of characters to the individual address. Sending 0xFF in the address field will set the new password if setting the password is enabled. Sending 0xFF will disable setting the password and clear the new password buffer if the password is set successfully. Example: the current commit password is “Analog123” (the default password); to change it to a new password “Admx2001pwd”, write the ASCII values of the characters to the current and new password buffers respectively, by sending the data along with the appropriate address (i.e. “Admx2001pwd” to address field 0 to 10, “Analog123” to address field 12 to 20). Once this is done, write 0xFE to verify the current commit password is correct. If this returns a success status, write 0xFF to set the new password. Refer to the Calibration Commands table for details about the address and data fields. Note max allowed password length is 12. If current password length is less than 12, it is ok to send the password that is less than 12 characters.

Set Password Command Mapping

Write Command	Address	Data range	Data type	Description
0x1c	Write new commit password character by character as ASCII values to new password buffer
	0 1 2 … 10 11	26 upper and 26 lower case letters, 10 digits, and 33 special characters Space char (0x20) not allowed	ASCII value of Nth character of the new password, as indicated by address field value	Send char 0 of the new password Send char 1 of the new password Send char 2 of the new password … Send char 10 of the new password Send char 11 of the new password
	Write current password character by character as ASCII values to current password buffer
	12 13 14 … 22 23	26 upper and 26 lower case letters, 10 digits, and 33 special characters Space char (0x20) not allowed	ASCII value of Nth character of the current password, as indicated by address field value	Send char 0 of the current password Send char 1 of the current password Send char 2 of the current password … Send char 10 of the current password Send char 11 of the current password
	0xFE	N/A	N/A	Check if the current password is correct. If the password in the password bits is correct, return success status and enable writing of new passwords. Otherwise block writing of the new password and clear the current password bits
	0xFF	N/A	N/A	Commit the new password. The new password won’t be committed unless the new password write has been enabled by writing 0xFE. Any error will clear the new password bits

CAL_STORE (0x08)

CAL_STORE command is used to store the calibration addresses corresponding to the calibration coefficients. The first 4 bits of the address need to be set to the voltage and current gain for which the calibration coefficients are to be stored. The bit 14 is used to choose between the MSB and the LSB of the 64-bit double valued calibration coefficient to be stored. The calibration coefficient is set by appropriately setting the bit 13 to bit 10. Refer to the Store Calibration Coefficients Commands table for details about the address and data fields.

Store Calibration Coefficients Command Mapping

Write Command	Address	Data range	Data type	Description
0x08	Bit 14	0 or 1	1-bit address	Coefficients LSB/MSB is decided by bit 14 0 - LSB of double value 1 - MSB of double value
	Bit 13 to bit 10	Calibration coefficients (see Calibration Coefficient Register Format table below)	4-bit address	Calibration coefficient to be stored
	Bit 9 to bit 4	N/A	N/A	Redundant bits, can default to 0
	Bit 3 to bit 2	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Current gain of coefficients
	Bit 1 to bit 0	0 to 3, i.e. 00, 01, 10, 11	2-bit address	Voltage gain of coefficients

Calibration Coefficient Register Format

Address (bit 13 to bit 10)	Selected Coefficient
0b0000	Ro
0b0001	Xo
0b0010	Go
0b0011	Bo
0b0100	Rs
0b0101	Xs
0b0110	Gs
0b0111	Bs
0b1000	Rg
0b1001	Xg
0b1010	Gg
0b1011	Bg

COMP_STORE (0x0D)

COMP_STORE command is used to store the compensation addresses corresponding to the compensation coefficients. The first 4 bits of the address should be set to 0, because the same compensation coefficients are used for all gain settings. The bit 14 is used to choose between the MSB or the LSB of the 64-bit double valued compensation coefficient to be stored. The compensation coefficient is set by appropriately setting the bit 13 to bit 10. Refer to the Store Compensation Commands table for details about the address and data fields Note: compensation feature is in development, the gain values in address bit 3 to bit 0 are defaulted to 0.

Store Compensation Coefficients Command Mapping

Write Command	Address	Data range	Data type	Description
0x08	Bit 14	0 or 1	1-bit address	Coefficients LSB/MSB is decided by bit 14 0 - LSB of double value 1 - MSB of double value
	Bit 13 to bit 10	Compensation coefficients (see Compensation Coefficient Register Format table below)	4-bit address	Compensation coefficient to be stored
	Bit 9 to bit 4	N/A	N/A	Redundant bits, can default to 0
	Bit 3 to bit 2	0 (same compensation for all gain settings)	2-bit address	Current gain of coefficients
	Bit 1 to bit 0	0 (same compensation for all gain settings)	2-bit address	Voltage gain of coefficients

Store Compensation Coefficient Register Format

Address (bit 13 to bit 10)	Selected Coefficient
0b0000	Ro
0b0001	Xo
0b0010	Go
0b0011	Bo
0b0100	Rs
0b0101	Xs
0b0110	Gs
0b0111	Bs
0b1000	Rg
0b1001	Xg
0b1010	Gg
0b1011	Bg