ADIS16400SLASHPCBZ datasheet(14/20 Pages) AD

14 / 20 page

ADIS16400/ADIS16405

Rev. B | Page 14 of 20

Digital Filtering

A programmable low-pass filter provides additional opportunity

for noise reduction on the inertial sensor outputs. This filter

contains two cascaded averaging filters that provide a Bartlett

window, FIR filter response (see Figure 15). For example,

SENS_AVG[2:0] = 100 (DIN = B804) sets each stage tap to 16.

When used with the default sample rate of 819.2 SPS, this

reduces the sensor bandwidth to approximately 16 Hz.

–20

–40

–60

–80

–100

–120

–140

0.001

0.01

0.1

FREQUENCY (

f/fS)

N = 2

N = 4

N = 16

N = 64

Figure 15. Bartlett Window FIR Frequency Response

(Taps = 2N + 1, Phase = N Samples)

Dynamic Range

There are three dynamic range settings for the gyroscope. The

lower dynamic range settings (±75°/sec and ±150°/sec) limit the

minimum filter tap sizes to maintain resolution. For example, set

SENS_AVG[10:8] = 010 (DIN = 0xB902) for a measurement

range of ±150°/sec. Because this setting can influence the filter

settings, program SENS_AVG[10:8], then SENS_AVG[2:0] if

more filtering is required.

Table 17. SENS_AVG

Bits

Settings

Description

Default = 0x0402

[15:11]

Not used

[10:8]

Measurement range (sensitivity) selection

100

±300°/sec (default condition)

010

±150°/sec, filter taps ≥ 4 (Bits[2:0] ≥ 0x02)

001

±75°/sec, filter taps ≥ 16 (Bits[2:0] ≥ 0x04)

[7:3]

Not used

[2:0]

Number of taps in each stage N = 2M

INPUT/OUTPUT FUNCTIONS

General-Purpose I/O

DIO1, DIO2, DIO3, and DIO4 are configurable, general-

purpose I/O lines that serve multiple purposes according to the

following control register priority: MSC_CTRL, ALM_CTRL,

and GPIO_CTRL. For example, set GPIO_CTRL = 0x080C

(DIN = 0xB308, and then 0xB20C) to set DIO1 and DIO2 as

inputs and DIO3 and DIO4 as outputs, with DIO3 set low and

DIO4 set high.

Table 18. GPIO_CTRL

Bits

Description

Default = 0x0000

[15:12]

Not used

[11]

General-Purpose I/O Line 4 (DIO4) data level

[10]

General-Purpose I/O Line 3 (DIO3) data level

[9]

General-Purpose I/O Line 2 (DIO2) data level

[8]

General-Purpose I/O Line 1 (DIO1) data level

[7:4]

Not used

[3]

General-Purpose I/O Line 4 (DIO4), direction control

1 = output, 0 = input

[2]

General-Purpose I/O Line 3 (DIO3), direction control

1 = output, 0 = input

[1]

General-Purpose I/O Line 2 (DIO2), direction control

1 = output, 0 = input

[0]

General-Purpose I/O Line 1 (DIO1), direction control

1 = output, 0 = input

Input Clock Configuration

The input clock allows for external control over sampling in the

ADIS16400/ADIS16405. Set GPIO_CTRL[3] = 0 (DIN =

0x0B200) and SMPL_PRD[7:0] = 0x00 (DIN = 0xB600) to enable

this function. See Table 2 and Figure 4 for timing information.

Data Ready I/O Indicator

The factory default sets DIO1 as a positive data ready indicator

signal. The MSC_CTRL[2:0] register provides configuration

options for changing this. For example, set MSC_CTRL[2:0] =

100 (DIN = 0xB404) to change the polarity of the data ready

signal for interrupt inputs that require negative logic inputs for

activation. The resulting pulse width is be between 100 μs and

200 μs over all conditions.

Table 19. MSC_CTRL

Bits

Description

Default = 0x0006

[15:12]

Not used

[11]

Memory test (clears on completion)

1 = enabled, 0 = disabled

[10]

Internal self-test enable (clears on completion)

1 = enabled, 0 = disabled

[9]

Manual self-test, negative stimulus

1 = enabled, 0 = disabled

[8]

Manual self-test, positive stimulus

1 = enabled, 0 = disabled

[7]

Linear acceleration bias compensation for gyroscopes

1 = enabled, 0 = disabled

[6]

Linear accelerometer origin alignment

1 = enabled, 0 = disabled

[5:3]

Not used

[2]

Data ready enable

1 = enabled, 0 = disabled

[1]

Data ready polarity

1 = active high, 0 = active low

[0]

Data ready line select

1 = DIO2, 0 = DIO1

ADIS16400/PCBZ датащи(PDF) 14 Page - Analog Devices

ADIS16400/PCBZ датащи(HTML) 14 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

датащи скачать

ссылки URL