BMA222-SHUTL Bosch Sensortec, BMA222-SHUTL Datasheet - Page 33

• Manufacturer Part Number: BMA222-SHUTL
• Description: BMA222 DAUGHTERCARD FOR DEV KIT
• Manufacturer: Bosch Sensortec
• Series: -r

Specifications of BMA222-SHUTL

• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±2g, 4g, 8g, 16g
• Interface: I²C, Serial, SPI
• Sensitivity: 64LSB/g, 32LSB/g, 16LSB/g, 8LSB/g
• Voltage - Supply: -
• Embedded: No
• Utilized Ic / Part: BMA222
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 828-1026

Like blocking_theta, used with orientation recognition, the parameter_theta stands for a user-
defined setting. In this case the content of the (0x2E) flat_theta bits. The possible flat angles
also range from 0° to 44.8°. To ensure proper operation, parameter_theta has to be less than or
equal to blocking_theta.
The flat interrupt is enabled (disabled) by writing ´1´ (´0´) to bit (0x16) flat_en. The flat interrupt
is generated if the flat value has changed and the new value is stable for at least the time given
by the (0x2F) flat_hold_time bits. The flat value is stored in the (0x0C) flat bit if the interrupt is
enabled. This value is ´1´ if the device is in the flat position, it is ´0´ otherwise. The content of
the (0x0C) flat bit is changed only if the interrupt is generated. The interrupt is automatically
cleared after one sample period. Its status is stored in the (0x09) flat_int bit. If temporary or
latched interrupt mode is used, after the generation of the interrupt the changed (0x0C) flat
value is kept fixed as long as the interrupt persists (e. g. until the latch time expires or the
interrupt is reset). After clearing the interrupt, the (0x0C) flat value is only updated with the next
following value change (i.e. with the next occurring interrupt).
The meaning of the (0x2F) flat_hold_time bits can be seen from table 22.
4.8.9 Low-g interrupt
This interrupt is based on the comparison of acceleration data against a low-g threshold, which
is most useful for free-fall detection.
The interrupt is enabled (disabled) by writing ´1´ (´0´) to the (0x17) low_en bit. There are two
modes available, ‘single’ mode and ‘sum’ mode. In ‘single’ mode, the acceleration of each axis
is compared with the threshold; in ‘sum’ mode, the sum of absolute values of all accelerations
|acc_x| + |acc_y| + |acc_z| is compared with the threshold. The mode is selected by the
contents of the (0x24) low_mode bit: ´0´ means ‘single’ mode, ´1´ means ‘sum’ mode.
The low-g threshold is set through the (0x23) low_th register. 1 LSB of (0x23) low_th always
corresponds to an acceleration of 7.81 mg (i.e. increment is independent from g-range setting).
Rev. 1.0
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such
as copying and passing on to third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
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Table 22: Meaning of flat_hold_time
flat_hold_time
parameter
(0x2F)
00b
01b
10b
11b
8
Data sheet
BMA222
Page 33
_
theta
.
1024 ms
2048 ms
512 ms
Time
0
Bosch Sensortec
07 March 2011