ADIS16265(RevF) Просмотр технического описания (PDF) - Analog Devices
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ADIS16265 Datasheet PDF : 20 Pages
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ADIS16260/ADIS16265
Sensor Bandwidth
The gyroscope signal chain has several filter stages that shape
its frequency response. Figure 15 provides a block diagram of
each filter stage and Table 15 lists the SENS_AVG register
controls for bandwidth.
Ce
RATE
FILT
FROM
GYRO
SENSOR
fC
740Hz
N
N
fC =
2
1
× R × CT
R = 90kΩ
CT = CINT + Ce
N = 2m
m = SENS_AVG[2:0]
Figure 15. Signal Processing Diagram
Table 15. SENS_AVG Bit Descriptions
Bits
Description (Default = 0x0402)
[15:11] Not used.
[10:8] Measurement range (sensitivity) selection.
100 = ±320°/sec (default condition).
010 = ±160°/sec, filter taps ≥ 4 (Bits[2:0] ≥ 0x02).
001 = ±80°/sec, filter taps ≥ 16 (Bits[2:0] ≥ 0x04).
7
Primary pole setting (k).
1: CINT = 0.0047 μF (bandwidth = 330 Hz).
0: CINT = 0.0377 μF (bandwidth = 50 Hz).
[6:3]
Not used.
[2:0]
Number of taps in each stage; value of m in N = 2m.
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 16). For example, set
SENS_AVG[2:0] = 100 (DIN = 0xB804) to set each stage to 16
taps. When used with the default sample rate of 256 SPS, this
reduces the bandwidth of the digital filter to approximately 5.2 Hz.
0
–20
–40
–60
–80
–100
N=2
–120
N=4
N = 16
N = 64
–140
0.001
0.01
0.1
1
FREQUENCY (f/fS)
Figure 16. Digital Filter Frequency, Bartlett Window FIR Filter
(Phase = N Samples)
Data Sheet
Dynamic Range
The SENS_AVG[10:8] bits provide three dynamic range settings
for this gyroscope. The lower dynamic range settings (±80°/sec
and ±160°/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 ±160°/sec. Because this
setting can influence the filter settings, program SENS_AVG[10:8]
and then SENS_AVG[2:0] if more filtering is required.
Calibration
The GYRO_OFF and GYRO_SCALE registers provide user
controls for making in-system adjustments to offset and scale
factor.
FROM INTERNAL
PROCESSING
TO OUTPUT
REGISTERS
GYRO_OFF
GYRO_SCALE
Figure 17. User Calibration Registers
Table 16. GYRO_OFF Bit Descriptions
Bits Description (Default = 0x0000)
[15:12] Not used.
[11:0] Offset adjustment factor, twos complement format,
0.018315°/sec per LSB.
Examples follow:
0x000: Add 0°/sec to gyroscope data.
0x001: Add 0.018315°/sec to gyroscope data.
0x0AA: Add 3.11355°/sec to gyroscope data.
0xF0F: Subtract 4.41392°/sec from gyroscope data.
0xFFF: Subtract 0.018315°/sec from gyroscope data.
Table 17. GYRO_SCALE Bit Descriptions
Bits Description (Default = 0x0800)
[15:12] Not used.
[11:0] Scale adjustment factor, offset binary format,
0.00048828/LSB.
Examples follow:
0x000: Multiply output by 0.
0x7F0: Multiply gyroscope data by 0.99218.
0x800: Multiply output by 1.
0x8A0: Multiply output by 1.077812.
0xFFF: Multiply output by 1.9995.
Rev. F | Page 14 of 20
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