ADIS16354SLASHPCBZ datasheet(17/28 Pages) AD

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ADIS16354

Rev. 0 | Page 17 of 28

CALIBRATION

For applications that require point-of-use calibration, the

ADIS16354 provides bias correction registers for all six sensors.

Table 11, Table 12, Table 13, and Table 14 provide the details

required for using these registers to calibrate the ADIS16354

sensors.

Table 11. Gyroscope Bias Correction Registers

Addresses

Common Parameters

XGYRO_OFF

0x1B, 0x1A

Default value = 0x0000

YGYRO_OFF

0x1D, 0x1C

Scale = 0.018315°/s per LSB

ZGYRO_OFF

0x1F, 0x1E

Twos complement, read/write

Table 12. Gyroscope Bias Correction Register Bits

Bits

Description

[15:13]

Not used

[12:0]

Data bits, typical adjustment range = ±75°

Table 13. Accelerometer Bias Correction Registers

Addresses

Common Parameters

XACCL_OFF

0x21, 0x20

Default value = 0x0000

YACCL_OFF

0x23, 0x22

Scale = 0.4672 mg per LSB

ZACCL_OFF

0x25, 0x24

Twos complement, read/write

Table 14. Accelerometer Bias Correction Register Bits

Bits

Description

[15:12]

Not used

[11:0]

Data bits, typical adjustment range = ±947 mg

Manual Bias Calibration

Because each offset bias register has read/write access, the bias

of each sensor is adjustable. For example, if an output offset of

0.18°/s is observed in the Z-axis gyroscope, the ZGYRO_OFF

accuracy. Using its sensitivity of 0.018315°/s, an adjustment of

−10 LSBs is required. The twos complement, hexadecimal code

of −10 LSBs is 0x1FF6.

To implement this calibration factor, use the following

pseudocode:

Write 0xF6 to Address 0x1E, then write 0x1F to Address 0x1F

This step reduces the 0.18°/s error term to 0.00315°/s.

Automatic Bias Null Calibration

The ADIS16354 provides a single-command, automatic bias

calibration for all three gyroscope sensors. The COMMAND

gyroscope output registers, then loads the three bias correction

registers with values that return their outputs to zero (null). A

single register write command starts this process (see Table 16).

Write 0x01 to Address 0x3E

Precision Automatic Bias Null Calibration

The ADIS16354 also provides a single-command function that

incorporates the optimal averaging time for generating the

appropriate bias correction factors for all three gyroscope sensors.

This command requires approximately 30 seconds to complete.

For optimal calibration accuracy, the device should be stable

(no motion) for this entire period. Once it has started, a reset

command is required to stop it prematurely, if required. The

following sequence starts this calibration option (see Table 16):

Write 0x10 to Address 0x3E

Restoring Factory Calibration

The ADIS16354 factory calibration can be restored by returning

the contents of each bias correction register to their default

value of zero. This command also flushes all of the data from

the digital filter taps. To accomplish this function for all six

sensor signal paths (see Table 16),

Write 0x02 to Address 0x3E

Linear Acceleration Bias Compensation (Gyroscopes)

The ADIS16354 provides compensation for acceleration

influences on the gyroscopes’ bias behavior, using the

MSC_CTRL register.

Set Bit 7 of Address 0x34 to 1 (see Table 29)

Linear Acceleration Origin Alignment

The ADIS16354 provides origin alignment for the accelerometers

to the point of percussion (see Figure 5), using the MSC_CTRL

Set Bit 6 of Address 0x34 to a 1 (see Table 29)

GLOBAL COMMANDS

The ADIS16354 provides global commands for common

operations such as calibration, flash update, auxiliary DAC

latch, and software reset. Each global command has a unique

control bit assigned to it in the COMMAND register and is

initiated by writing a 1 to its assigned bit.

The flash update command writes the contents of each non-

volatile register into flash memory for storage. This process

takes approximately 100 ms and requires the power supply

voltage to be within specification for the duration of the event.

Note that this operation also automatically follows the autonull,

precision autonull, and factory reset commands. After waiting

the appropriate time for the flash update to complete, verify

successful completion by reading the STATUS register (flash

update error = 0, if successful).

The DAC latch command loads the contents of AUX_DAC into

the DAC latches, which control the actual output level. This

overcomes the challenge of discontinuous outputs that would

otherwise be associated with two separate write cycles for upper

and lower bytes. Finally, the software reset command sends the

ADIS16354 digital processor into a restart sequence, effectively

accomplishing the same tasks as the RST line.

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