BMA020 Bosch Sensortec, BMA020 Datasheet - Page 16

• Manufacturer Part Number: BMA020
• Description: 3-AXIS ACCELEROMETER DIGITAL I/F
• Manufacturer: Bosch Sensortec

Specifications of BMA020

• Axis: X, Y, Z
• Acceleration Range: ± 2g, 4g, 8g
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g
• Voltage - Supply: 2 V ~ 3.6 V
• Output Type: Digital
• Bandwidth: 3kHz
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Package / Case: 12-LGA
• For Use With: 828-1014 - BMA020 TRIBOX DEMO BOARD W/USB828-1008 - BMA020 DAUGHTERCARD FOR DEV KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 828-1000-2

3.2.9 Any_motion_thres, any_motion_dur
For the evaluation using “any motion” criterion successive acceleration data from digital filter
output are stored and moving differences for all axes are built. To calculate the difference the
acceleration values of all axes at time t0 are compared to values at t0+3/(2*bandwidth). The
difference of both values is equal to the difference of two successive moving averages (from
three data points).
The differential value is compared to a global critical threshold any_motion_thres (address 10h,
bits 7-0). Interrupt can be generated when the absolute value of measured difference is higher
than the programmed threshold for long enough duration defined by any_motion_dur (address
11h, bits 7 and 6).
Any_motion_thres and any_motion_dur data are unsigned integer. Any_motion_thres LSB size
corresponds to 15.6mg for +/- 2g range and scales with range selection (section 3.1.2).
Any motion criterion is valid if
An interrupt is set if
The any motion interrupt is reset if NOT(any_motion criterion_x OR any_motion criterion_y OR
Table 8: any_motion_dur settings
Any_motion_dur is used to filter the motion profile and also to define a minimum interrupt
duration because the reset condition is also filtered.
Any_motion_thres can be used to generate an any_motion interrupt or to put BMA020 in alert
mode to preload the low-g or high-g threshold logic (enables reduction of reaction time in
tumbling mode); this is selected by alert bit (section 3.2.5). These two modes (any_motion and
alert) can not be turned on simultaneously.
Rev. 1.2
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Note: Specifications within this document are subject to change without notice.
any_motion_dur<1:0>
00
01
10
11
Digital, triaxial acceleration sensor
Number of required consecutive conditions
to set or reset the any motion interrupt
(any motion criterion_x OR any motion criterion_y OR any
motion criterion_z) for any_motion_dur consecutive times.
any_motion criterion_z) for any_motion_dur consecutive
times.
|acc(t0)-acc(t0+3/(2*bandwidth))| ≥ any_motion_thres.
Data sheet
BMA020
Page 16
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Bosch Sensortec
30 May 2008