BMA253
Data sheet
Page 23
4.5.1 Slow compensation
Slow compensation is based on a 1st order high-pass filter, which continuously drives the
average value of the output data stream of each axis to zero. The bandwidth of the high-pass
filter is configured with bit (0x37) cut_off according to Table 7.
Table 7: Compensation period settings
(0x37)
cut_off
high-pass filter
bandwidth
Example
bw = 500 Hz
0b
1b
*bw: please insert selected decimal data bandwidth value [Hz] from table 4
The slow compensation can be enabled (disabled) for each axis independently by setting the
bits (0x36) hp_x_en, hp_y_en, hp_z_en to ´1´ (´0´), respectively.
Slow compensation should not be used in combination with low-power mode. In low-power
mode the conditions (availability of necessary data) for proper function of slow compensation
are not fulfilled.
4.5.2 Fast compensation
Fast compensation is a one-shot process by which the compensation value is set in such a way
that when added to the raw acceleration, the resulting acceleration value of each axis
approaches the target value. This is best suited for “end-of-line trimming” with the customer’s
device positioned in a well-defined orientation. For fast compensation the g-range has to be
switched to 2g.
The algorithm in detail: An average of 16 consecutive acceleration values is computed and the
difference between target value and computed value is written to (0x38, 0x39, 0x3A)
offset_filt_x/y/z. The public registers (0x38, 0x39, 0x3A) offset_filt_x/y/z are updated with the
contents of the internal registers (using saturation if necessary) and can be read by the user.
Fast compensation is triggered for each axis individually by setting the (0x36) cal_trigger bits as
shown in Table 8:
Table 8: Fast compensation axis selection
(0x36)
cal_trigger
Selected Axis
00b
01b
10b
11b
none
x
y
z
BST-BMA253-DS000-01 | Revision 1.0 | August 2015
Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
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