ADIS16IMU5SLASHPCBZ datasheet(34/46 Pages) AD

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Data Sheet

ADIS16575/ADIS16576/ADIS16577

USER REGISTER DEFINITIONS

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Rev. 0 | 34 of 46

Table 88. Burst Read SPI Communication Sequence with Checksum (Continued)

16-Bit SPI Word

16-Bit Burst Register

32-Bit Burst Registers

Comments

Y_ACCL_UPR or Y_DELTVEL_UPR

Z_GYRO_LWR or Z_DELTANG_LWR

Not applicable.

Z_ACCL_UPR or Z_DELTVEL_UPR

Z_GYRO_UPR or Z_DELTANG_UPR

Not applicable.

TEMP

X_ACCL_LWR or X_DELTVEL_LWR

Not applicable.

DATA_CNTR or TIMESTAMP_LWR

X_ACCL_UPR or X_DELTVEL_UPR

Not applicable.

SPI_CHKSUM

Y_ACCL_LWR or Y_DELTVEL_LWR

Not applicable.

Not applicable

Y_ACCL_UPR or Y_DELTVEL_UPR

Not applicable.

Not applicable

Z_ACCL_LWR or Z_DELTVEL_LWR

Not applicable.

Not applicable

Z_ACCL_UPR or Z_DELTVEL_UPR

Not applicable.

Not applicable

TEMP

Not applicable.

Not applicable

DATA_CNTR or TIMESTAMP_LWR

DATA_CNTR or TIMESTAMP_LWR. When scaled

sync mode is disabled, DATA_CNTR is transmit-

ted. When scaled sync mode is enabled, TIME-

STAMP_LWR replaces DATA_CNTR.

Not applicable

0s or TIMESTAMP_UPR

TIMESTAMP_UPR bit width selected by TS_32 in the

MSC_CTRL register

Not applicable

SPI_CHKSUM

Not applicable

As indicated in Table 88, the the SPI_CHKSUM value follows the

0s and the TIME_STAMP_UPR value in the burst read sequence.

Once all sensor data and timestamp information is read, an addi-

tional 16-bit transaction is required to read the checksum. It is

important to note that the checksum calculation does not include

FIFO_CNT and DIAG_STAT registers, as mentioned in the not

included in checksum comments in Table 88.

This implementation of SPI_CHKSUM provides a robust method

for ensuring data integrity in SPI communications with the IMU,

allowing for flexible read sequences while maintaining the ability to

detect transmission errors.

CALIBRATION, BIAS ADJUSTMENT, AND

CONTINUOUS BIAS ESTIMATION (CBE)

The ADIS16575/ADIS16576/ADIS16577 employ a comprehensive

approach to calibration and bias management for its inertial sen-

sors (accelerometers and gyroscopes). Each sensor's signal chain

includes unique correction formulas derived from extensive charac-

terization of bias, sensitivity, alignment, and point of percussion (for

accelerometers) over the −40°C to +85°C temperature range.

While the factory-derived correction formulas are not user accessi-

ble, the devices provide the following registers for individual sensor

bias adjustment:

1. Gyroscope bias registers: XG_BIAS_LWR, XG_BIAS_UPR,

YG_BIAS_LWR, YG_BIAS_UPR, ZG_BIAS_LWR, and

ZG_BIAS_UPR

2. Accelerometer bias registers: XA_BIAS_LWR, XA_BIAS_UPR,

YA_BIAS_LWR, YA_BIAS_UPR, ZA_BIAS_LWR, and

ZA_BIAS_UPR

Each axis uses two 16-bit registers (xx_BIAS_LWR and

(xx_BIAS_UPR) to form a 32-bit bias adjustment value, matching

the format and scaling of the sensor output registers. These user-

adjustable corrections are applied after the factory-derived formulas

in the signal chain, which processes at a user-defined rate of 2000

Hz or 4000 Hz with the internal sample clock.

To enhance long-term stability, the ADIS16575/ADIS16576/

ADIS16577 feature CBE. The NULL_CNFG register controls CBE,

with Bits[13:8] enabling and disabling CBE for each axis and

Bits[3:0] setting the estimation time base. The bias correction

update command (GLOB_CMD, Bit 0) applies the latest CBE esti-

mates to the bias adjustment registers.

Users can adjust bias through the following two methods:

1. Manual adjustment. Direct writing to bias registers for immedi-

ate correction.

2. Automatic adjustment. Configuring NULL_CNFG for CBE and

periodically applying updates.

This integrated approach to calibration and bias management, com-

bining factory calibration, user-accessible adjustments, and continu-

ous estimation, provides powerful tools to optimize the ADIS16575/

ADIS16576/ADIS16577 performance across varying conditions and

applications.

Calibration, Gyroscope Bias (XG_BIAS_LWR

and XG_BIAS_UPR)

Table 89. XG_BIAS_LWR Register Definition

Addresses

Default

Access

Flash Backup

0x40, 0x41

0x0000

R/W

Yes

Table 90. XG_BIAS_LWR Bit Definitions

Bits

Description

[15:0]

X-axis gyroscope offset correction; lower word

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