BMA250 Bosch Sensortec, BMA250 Datasheet - Page 32

• Manufacturer Part Number: BMA250
• Description: 3-AXIS ACCELEROMETER DIGITAL I/F
• Manufacturer: Bosch Sensortec
• Series: -r

Specifications of BMA250

• Featured Product: BMA250 - Digital, Triaxial Acceleration Sensor
• Axis: X, Y, Z
• Acceleration Range: ±2g, 4g, 8g, 16g
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g, 16LSB/g
• Voltage - Supply: 1.62 V ~ 3.6 V
• Output Type: I²C™, SPI™
• Bandwidth: 8Hz ~ 1kHz
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Package / Case: 12-VQFN
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With: 828-1024 - BMA250 DAUGHTERCARD FOR DEV KIT
• Other names: 828-1023-2

one stable period of the (0x0C) orient value. The interrupt status is stored in the (0x09)
orient_int bit.
If temporary or latched interrupt mode is used, after the generation of the interrupt the changed
(0x0C) orient 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) orient is only updated
with the next following value change (i.e. with the next occurring interrupt). In order to ensure
the continuous availability of up-to-date orientation data it is therefore optimal to use the non-
latched interrupt. It is strongly advised against using latched interrupt mode or temporary
interrupt mode with latch times above 50 ms for orient recognition.
4.8.7.1 Orientation blocking
The change of the (0x0C) orient value and – as a consequence – the generation of the interrupt
can be blocked according to conditions selected by setting the value of the (0x2C)
orient_blocking bits as described by table 21.
The theta blocking is defined by the following inequality:
The parameter blocking_theta of the above given equation stands for the contents of the (0x2D)
orient_theta bits. Hereby it is possible to define a blocking angle between 0° and 44.8°. The
internal blocking algorithm saturates the acceleration values before further processing. As a
consequence, the blocking angles are strictly valid only for a device at rest; they can be different
if the device is moved.
Example:
To get a maximum blocking angle of 19° the parameter blocking_theta is determined in the
following way: (8 * tan(19°) )² = 7.588, therefore, blocking_value = 8dec = 001000b has to be
chosen.
Rev. 1.0
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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.
Table 21: Blocking conditions for orientation recognition
orient_blocking
(0x2C)
tan
00b
01b
10b
11b


blocking
Page 32 / not for publishing
value of orient is not stable for at least 100 ms
8
_
Data sheet
BMA250
acceleration slope in any axis > 0.2 g
acceleration slope in any axis > 0.4 g
theta
.
theta blocking
theta blocking
theta blocking
Conditions
no blocking
or
or
or
Bosch Sensortec
03 March 2011