ADIS16IMU5SLASHPCBZ datasheet(40/46 Pages) AD

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Data Sheet

ADIS16575/ADIS16576/ADIS16577

USER REGISTER DEFINITIONS

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Table 126. NULL_CNFG Bit Definitions (Continued)

Bits

Description

depending on the configuration), time base; tA = 64 × tB, average

time.

The NULL_CNFG register (see Table 125 and Table 126) provides

configuration controls for the CBE, which is associated with the bias

correction update command in Register GLOB_CMD, Bit 0 (see

Table 128). The CBE tracks a moving average of the sensor output

for each enabled channel (gyroscope or accelerometer) over a

programmable time window defined by Bits[3:0] of the NULL_CNFG

This moving average is calculated continuously and represents

the estimated bias for each sensor axis. The resulting bias values

are automatically written to the corresponding user offset registers,

where they are applied to correct the sensor outputs in real time.

Bits[13:8] of the NULL_CNFG register control whether bias correc-

tion is enabled for each specific sensor axis.

The factory default configuration for the NULL_CNFG register ena-

bles the bias null command for the gyroscopes, disables the bias

null command for the accelerometers, and sets the average null

time to approximately 32 seconds.

GLOBAL COMMANDS (GLOB_CMD)

Table 127. GLOB_CMD Register Definition

Addresses

Default

Access

Flash Backup

0x68, 0x69

Not applicable

Table 128. GLOB_CMD Bit Definitions

Bits

Description

[15:8]

Not used

Software reset

Not used

FIFO flush

Flash memory test

Flash memory update

Sensor self-test

Factory calibration restore

Bias correction update

The GLOB_CMD register (see Table 127 and Table 128) provides

trigger bits for several operations. Writing a 1 to the appropriate

bit in the GLOB_CMD register initiates the corresponding function.

During the execution of the flash memory update and factory

calibration restore commands, data production stops, pulsing on the

DR pin halts, and the SPI does not respond to requests. For other

commands, the SPI remains accessible. Refer to the Table 1 for the

execution time of each GLOB_CMD command.

Software Reset

Use the following DIN sequence to set Register GLOB_CMD, Bit

7 = 1, which triggers a reset: 0xE880, then 0xE900. This reset

clears all data, reinitializes the inertial sensors, and then restarts

data sampling and processing. This function provides a firmware

alternative to toggling the RST pin (see Table 10, Pin 8).

FIFO Flush

Use the following DIN sequence to set Register GLOB_CMD, Bit

5 = 1, which triggers a FIFO flush: 0xEA80, then 0xEB00. This com-

mand clears all data currently stored in the FIFO buffer, ensuring

that subsequent data reads start with fresh data. The FIFO flush

operation is particularly useful when resetting the FIFO after an

error condition or before starting a new data acquisition session.

Unlike some other global commands, the SPI remains active and

responsive during the execution of the FIFO flush command.

Flash Memory Test

Use the following DIN sequence to set Register GLOB_CMD, Bit

4 = 1, which tests the flash memory: 0xE810, then 0xE900. The

command performs a CRC computation on the flash memory,

including program memory and factory register data (excluding user

the factory configuration process. If the current CRC value does

not match the original CRC value, Register DIAG_STAT, Bit 6 (see

Table 15), rises to 1, indicating a failing result.

Flash Memory Update

Use the following DIN sequence to set Register GLOB_CMD, Bit 3

= 1, which triggers a backup of all user-configurable registers in the

flash memory: 0xE808, then 0xE900. Register DIAG_ STAT, Bit 2

(see Table 15), identifies success (0) or failure (1) in completing this

process.

Sensor Self Test

Use the following DIN sequence to set Register GLOB_CMD, Bit

2 = 1, which triggers the self test routine for the inertial sensors:

0xE804, then 0xE900. The self test routine uses the following steps

to validate the integrity of each inertial sensor:

1. Test communications to each sensor.

2. Measure the output on each sensor.

3. Activate an internal stimulus on the mechanical elements of

each sensor to move them predictably and create an observa-

ble response.

4. Measure the output response on each sensor.

5. Deactivate the internal stimulus on each sensor.

6. Calculate the difference between the sensor measurements

from Step 2 (stimulus is off) and Step 4 (stimulus is on).

7. Compare the difference with internal pass and fail criteria.

8. Report the pass and fail results to the DIAG_STAT register, Bit

5 (see Table 15).

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