ADIS16475-1SLASHPCBZ datasheet(13/37 Pages) AD

13 / 37 page

Data Sheet

ADIS16475

Rev. D | Page 13 of 37

The factory calibration of the accelerometer applies the following

correction formulas to the data of each accelerometer:





















































































where:

aXC, aYC, and aZC are the accelerometer outputs (post calibration).

m11, m12, m13, m21, m22, m23, m31, m32, and m33 provide scale and

alignment correction.

aX, aY, and aZ are the accelerometer outputs (precalibration).

bX, bY, and bZ provide bias correction.

p12, p13, p21, p23, p31, and p32 provide a point of percussion

alignment correction (see Figure 47).

ω2XC, ω2YC, and ω2ZC are the square of the gyroscope outputs

(post calibration).

All of the correction factors in this relationship come from

direct observation of the response of each accelerometer at

multiple temperatures over the calibration temperature range

(−40°C ≤ TC ≤ +85°C). These correction factors are stored

in the flash memory bank, but they are not available for

observation or configuration. MSC_CTRL, Bit 6 (see Table 105)

provides the only user configuration option for the factory

calibration of the accelerometers: an on/off control for the point of

percussion, alignment function. See Figure 45 for more details

on the user calibration options available for the accelerometers.

Bartlett Window FIR Filter

The Bartlett window finite impulse response (FIR) filter

(see Figure 22) contains two averaging filter stages in a cascade

configuration. The FILT_CTRL register (see Table 101) provides

the configuration controls for this filter.

FROM

MEMS

SENSOR

FACTORY

CALIBRATION

n = 1

ω(n)

n = 1

ω(n)

Figure 22. Bartlett Window FIR Filter Signal Path

Averaging/Decimating Filter

The second digital filter averages multiple samples together to

produce each register update. In this type of filter structure, the

number of samples in the average is equal to the reduction in

the update rate for the output data registers. The DEC_RATE

this filter.

FROM

USER

CALIBRATION

÷N

TO OUTPUT

REGISTERS

n = 1

ω(n)

Figure 23. Averaging/Decimating Filter Diagram

All communication between the ADIS16475 and an external

processor involves either reading the contents of an output

control register. The output data registers include the latest

sensor data, error flags, and identification information. The

control registers include sample rate, filtering, calibration, and

diagnostic options. Each user accessible register has two bytes

(upper and lower), each of which has its own unique address.

See Table 8 for a detailed list of all user registers, along with

their addresses.

TRIAXIAL

GYROSCOPE

TEMPERATURE

SENSOR

TRIAXIAL

ACCELLEROMETER

OUTPUT

REGISTERS

CONTROL

REGISTERS

CONTROLLER

SENSOR

SIGNAL

PROCESSING

Figure 24. Basic Operation of the ADIS16475

ADIS16475-1/PCBZ Datasheet(PDF) 13 Page - Analog Devices

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