Datasheet

Data Sheet
BMA456
Page 33
BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
Step Detector / Step Counter
The Step Counter algorithm is optimized on high accuracy, while Step Detector is optimized on low
latency. Both are running in parallel, once enabled, but the Step Detector interrupt output is mutually
exclusive with the Step Counter watermark interrupt. The Step Counter is optimized for wearable
devices and wrist use case.
In addition the Step Counter implements the function required for step counting in Android 4.4 and
higher as well: https://source.android.com/devices/sensors/sensor-types.html#step_counter.
The Step Detector implements the function required for step counting in Android 4.4 and higher:
https://source.android.com/devices/sensors/sensor-types.html#step_detector.
Step Counter:
Step Counter can be enabled in FEATURES_IN.step_counter.settings_26.en_counter.
The step counter accumulates the steps detected by the step detector interrupt, and makes available
the 32 bit current step counter value in the following 4 registers, each holding 8bit:
STEP_COUNTER_0, STEP_COUNTER_1, STEP_COUNTER_2 and corresponding,
STEP_COUNTER_3. There are situations when the step counting value is different than the sum of
steps detected by the step detector.
By enabling the FEATURES_IN.step_counter.settings_26.reset_counter flag, the accumulated step
number value is reset. Afterwards, the value of this flag is automatically reset and counting is restarted.
The step counter watermark option can be useful if host needs to receive an interrupt every time a
certain number of steps were counted. If FEATURES_IN.step_counter.settings_26.watermark_level is
set to 10 (holding an implicit factor of 20x), every 200 steps are counted an interrupt will be raised on
INT_STATUS_0.step_counter_out. As the steps are buffered internally, the output may be triggered
between 200-210 steps. The exact number of steps recorded is available in the registers
STEP_COUNTER_0, STEP_COUNTER_1, STEP_COUNTER_2 and STEP_COUNTER_3. When
the watermark level was reached, the corresponding interrupt bit is asserted,
INT_STATUS_0.step_counter_out.
Step Detector:
The Step Detector feature is optimized for low latency. If
FEATURES_IN.step_counter.settings_26.en_detector is set, an interrupt is triggered for every step
detected. So, every time a new step is detected, it asserts the corresponding interrupt output
INT_STATUS_0.step_counter_out.
Step Counter Presets (phone/wrist use case):
The integrated step counter can be configured to work with either phone platform or wrist platform.
The step counter parameters FEATURE_IN.step_counter.settings_1.param_1 to
FEATURE_IN.step_counter.settings_25.param_25 must be configured from the host side to either of
the configurations in the following table.