BMA222 Bosch Sensortec, BMA222 Datasheet - Page 20

• Manufacturer Part Number: BMA222
• Description: 3-AXIS ACCELEROMETER DIGITAL SMD
• Manufacturer: Bosch Sensortec

Specifications of BMA222

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 828-1025-2

By writing ´1´ to the (0x36) offset_reset bit, all offset compensation registers are reset to zero.
4.6.1 Slow compensation
Slow compensation is a quasi-continuous process which regulates the acceleration value of
each axis towards the target value by comparing the current value with the target and adding or
subtracting a fixed value depending on the comparison.
The algorithm in detail: If an acceleration value is larger (smaller) than the target value (0x37)
offset_target_x/y/z for a number of samples (given by the parameter Offset Period see table 11),
the internal offset compensation value (0x38, 0x039, 0x3A) offset_filt_x/y/z or (0x3B, 0x03C,
0x3D) offset_unfilt_x/y/z is decremented (incremented) by 4 LSB.
The public registers (0x38, 0x039, 0x3A) offset_filt_x/y/z and (0x3B, 0x03C, 0x3D)
offset_unfilt_x/y/z are not used for the computations but they are updated with the contents of
the internal registers (using saturation if necessary) and can be read by the user.
The compensation period offset_period is set by the (0x37) cut_off bit as represented in table
12:
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.
4.6.2 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 equals
the target value.
Rev. 1.0
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Note: Specifications within this document are subject to change without notice.
offset_target_x/y/z
Table 12: Compensation period settings
Table 11: Offset target settings
(0x37)
00b
01b
10b
11b
cut_off
(0x37)
0b
1b
Data sheet
BMA222
Page 20
Target value
Period
Offset
16
8
+1g
-1g
0g
0g
Bosch Sensortec
07 March 2011