ADIS16250/PCBZ 查看數據表（PDF） - Analog Devices

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ADIS16250/PCBZ

Dual-Axis Digital Inclinometer and Accelerometer

Analog Devices 

ADIS16250/ADIS16255

CALIBRATION

The ADIS16250/ADIS16255 are factory-calibrated for

sensitivity and bias. It also provides several user calibration

functions for simplifying field-level corrections. The calibra-

tion 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 ADIS16250/ADIS16255: 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 ADIS16250/ADIS16255

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 Scale1

Default Format

0x15,

0x14

0.018315°/sec 0x0000 Twos

complement

1 Scale is the weight of each LSB.

Access

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

Scale1 Default2 Format

0x17, 0x16 0.0487% 0x0800 Binary

1 Scale is the weight of each LSB.

2 Equates to a scale factor of one.

Table 12. GYRO_SCALE Bit Descriptions

Bit

Description

15:12

Not used

11:0

Data bits

Access

R/W

GLOBAL COMMANDS

The ADIS16250/ADIS16255 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

ADIS16250/ADIS16255 digital processor into a restart sequence,

effectively doing the same thing as the RST line.

Table 13. COMMAND Register Definition

Address

Default

Format

0x3F, 0x3E N/A

N/A

Access

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

Rev. D | Page 14 of 20

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