Datasheet

Preliminary Data Sheet
BMA400
Page 52 /
Confidential
BST-BMA400-DS000-00 | Version 0.1 | November 2017 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
The threshold for the orientation change interrupt can be configured in the register
ORIENTCH_CONFIG1.orient_thres. The threshold configuration has 8 bits and a resolution of
8mg/LSB. In case the acceleration is above the reference acceleration stored for last position for
defined period of time ORIENTCH_CONFIG3.orient_dur; the BMA400 orientation change condition is
true. In case the stability check is selected the orientation must be stable within the stability threshold
ORIENTCH_CONFIG2.stability_thres.
The minimum duration of a new orientation (which shall trigger an interrupt) can be configured in the
register ORIENTCH_CONFIG3.orient_dur. The duration register has 8 bits and a resolution of
10ms/LSB.
The stability evaluation mode can be configured in the Register ORIENTCH_CONFIG0.stability_mode.
Following configurations are supported for stability evaluation mode:
 stability check disable
 Difference to last value from filter acc_filt2
 Difference to last value from filter acc_filt_lp
ORIENTCH_CONFIG0.stability_mode
Description
b00
Stability disabled: the stability check is disabled. The
orientation change is based only on the difference and
duration condition to reference values
b01
Last ordinary acceleration: stability condition evaluated by
using the acc_filt2 acceleration
b10 or b11
Last low-pass filtered acceleration: stability condition
evaluated by using the low-pass filtered acceleration data
acc_filt_lp
When the duration condition is fulfilled, the reference orientation is updated according to the
configuration stored in the Register (ORIENTCH_CONFIG0.orient_refu). The reference update mode
supports following modes:
 no automatic update at all, the reference orientation will be updated by the user when needed
 update with output from filter acc_filt2
 update with output from filter acc_filt_lp
Summarized, the orientation changed interrupt supports following configuration:
 Axis selection for orientation evaluation
 Data source for data evaluation
o acc_filt2
o acc_filt_lp
 Stability mode configuration
o Stability check disabled
o Last acceleration from acc_filt2 for stability check
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