BMA222 Bosch Sensortec, BMA222 Datasheet - Page 26

• 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

BMA222
Bosch Sensortec
Data sheet
4.8.5.1 Enabling (disabling) for each axis
Any-motion detection can be enabled (disabled) for each axis separately by writing ´1´ (´0´) to
bits (0x16) slope_en_x, (0x16) slope_en_y, (0x16) slope_en_z. The criteria for any-motion
detection are fulfilled and the slope interrupt is generated if the slope of any of the enabled axes
exceeds the threshold (0x28) slope_th for [(0x27) slope_dur +1] consecutive times. As soon as
the slopes of all enabled axes fall or stay below this threshold for [(0x27) slope_dur +1]
consecutive times the interrupt is cleared unless interrupt signal is latched.
4.8.5.2 Axis and sign information of any motion interrupt
The interrupt status is stored in bit (0x09) slope_int. The any-motion interrupt supplies additional
information about the detected slope. The axis which triggered the interrupt is given by that one
of bits (0x0B) slope_first_x, (0x0B) slope_first_y, (0x0B) slope_first_z that contains a ´1´. The
sign of the triggering slope is held in bit (0x0B) slope_sign. If (0x0B) slope_sign = ´0´ (´1´), the
sign is positive (negative).
4.8.5.3 Serial interface and dedicated wake-up mode
When serial interface is active, any-motion detection logic is enabled if any of the axis specific
(0x16) slope_en_... register bits are set. To disable the any-motion interrupt, clear all the axis
specific (0x16) slope_en_... bits.
In the dedicated wake-up mode (see chapter 4.2.2), all three axes are enabled for any-motion
detection whether the individual axis enable bits are set or not.
4.8.6 Tap sensing
Tap sensing has a functional similarity with a common laptop touch-pad or clicking keys of a
computer mouse. A tap event is detected if a pre-defined slope of the acceleration of at least
one axis is exceeded. Two different tap events are distinguished: A ‘single tap’ is a single event
within a certain time, followed by a certain quiet time. A ‘double tap’ consists of a first such
event followed by a second event within a defined time frame.
Only one of the tap interrupts can be enabled at the same time. Single tap interrupt is enabled
(disabled) by writing ´1´ (´0´) to bit (0x16) s_tap_en. Double tap interrupt is enabled (disabled)
by writing ´1´ (´0´) to bit (0x16) d_tap_en. If one tries to enable both interrupts by writing ´1´ to
(0x16) s_tap_en and (0x16) d_tap_en, then only (0x16) d_tap_en keeps the value ´1´ and the
double tap interrupt is enabled.
The status of the single tap interrupt is stored in bit (0x09) s_tap_int, the status of the double tap
interrupt is stored in bit (0x09) d_tap_int.
The slope threshold for detecting a tap event is set by bits (0x2B) tap_th. The meaning of
(0x2B) tap_th depends on the range setting. 1 LSB of (0x2B) tap_th corresponds to a slope of
62.5mg in 2g-range, 125mg in 4g-range, 250mg in 8g-range, and 500mg in 16g-range.
In figure 7 the meaning of the different timing parameters is visualized:
Rev. 1.0
Page 26
07 March 2011
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Note: Specifications within this document are subject to change without notice.