BMA253
Data sheet
Page 31
4.7.6 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.
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.
While temporary latching is used do not simultaneously enable single tap interrupt and double
tap interrupt.
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 8 the meaning of the different timing parameters is visualized:
slope
1st tap
2nd tap
tap_th
time
tap_shock
tap_quiet
tap_dur
tap_shock
tap_quiet
single tap detection
double tap detection
12.5 ms
time
time
12.5 ms
Figure 8: Timing of tap detection
BST-BMA253-DS000-01 | Revision 1.0 | August 2015
Bosch Sensortec
© 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.
BOSCH [ Bosch Sensortec GmbH ]
