Preliminary Technical Data

ADIS16260/ADIS16265

Rev. PrB | Page 13 of 19

CALIBRATION

The ADIS16260/ADIS16265 are factory-calibrated for

sensitivity and bias. It also provides several user calibration

functions for simplifying field-level corrections. The calibration

factors are stored in nonvolatile memory and are applied using

the following linear calibration equation:

y = mx + b

where:

y is the calibrated output data.

x is the precalibration data.

m is the sensitivity scale factor.

b is the offset scale factor.

There are three options for system-level calibrations of the bias

in the ADIS16260/ADIS16265: auto-null, factory calibration

restore, and manual calibration updates. The auto-null and

factory reset options are described in the Global Commands

section. Optional field-level calibrations use the preceding

equation and require two steps:

1.

Characterize the behavior of the ADIS16260/ADIS16265 at

predefined critical operating conditions.

2.

Use this characterization data to calculate and load the

contents of GYRO_OFF (b) and GYRO_SCALE (m).

The GYRO_OFF provides a calibration range of ±37.5°/sec, and

its contents are nonvolatile. The GYRO_SCALE register

provides a calibration range of 0 to 1.9995, and its contents are

also nonvolatile.

Table 9. GYRO_OFF Register Definition

Address

Default

Format

Access

0x15,

0x14

0.018315°/sec

0x0000

Twos

complement

R/W

Table 10. GYRO_OFF Bit Descriptions

Bit

Description

15:12

Not used

11:0

Data bits

Table 11. GYRO_SCALE Register Definition

Address

Format

Access

0x17, 0x16

0.0487%

0x0800

Binary

R/W

Table 12. GYRO_SCALE Bit Descriptions

Bit

Description

15:12

Not used

11:0

Data bits

GLOBAL COMMANDS

The ADIS16260/ADIS16265 provide global commands for

common operations such as auto-null, factory calibration

restore, manual flash update, auxiliary DAC latch, and software

reset. Each of these global commands has a unique control bit

assigned to it in the COMMAND register and is initiated by

writing a 1 to its assigned bit.

The auto-null function does two things: it resets the contents of

the ANGL_OUT register to zero, and it adjusts the GYRO_OUT

register to zero. This automated adjustment takes two steps:

1.

Read GYRO_OUT.

2.

Write the opposite of this value into the GRYO_OFF

register. Sensor noise influences the accuracy of this step.

For optimal calibration accuracy, set the number of filtering

taps to its maximum, wait for the appropriate number of

samples to process through the filter, and then exercise this

option.

The factory calibration restore command sets the contents of

GYRO_OFF to 0x0000 and GYRO_SCALE to 0x0800, erasing

any field-level calibration contents. The manual flash update

writes the contents of each nonvolatile register into flash

memory for storage. This process takes approximately 50 ms

and requires the power supply voltage to be within specification

for the duration of the event. It is worth noting that this

operation also automatically follows the auto-null and factory

reset commands.

The DAC latch command loads the contents of AUX_DAC into

the DAC latches. Since the AUX_DAC contents must be updated

one byte at a time, this command ensures a stable DAC output

voltage during updates. Finally, the software reset command

sends the ADIS16260/ADIS16265 digital processor into a restart

sequence, effectively doing the same thing as the RST line.

Table 13. COMMAND Register Definition

Address

Default

Format

Access

0x3F, 0x3E

N/A

N/A

Write only

Table 14. COMMAND Bit Descriptions

Bit

Description

15:8

Not used

7

Software reset command

6:4

Not used

3

Manual flash update command

2

Auxiliary DAC data latch

1

Factory calibration restore command

0

Auto-null command