LSM6DSL Datasheet, PDF (17/113 Pages) STMicroelectronics – iNEMO inertial module: always-on 3D accelerometer and 3D gyroscope

LSM6DSL
Embedded low-power features
2.2
Absolute wrist tilt
The LSM6DSL implements in hardware the Absolute Wrist Tilt (AWT) function which allows
detecting when the angle between a selectable accelerometer semi-axis and the horizontal
plane becomes higher than a specific user-selectable value.
Configurable threshold and latency parameters are associated with the AWT function: the
threshold parameter defines the amplitude of the tilt angle; the latency parameter defines
the minimum duration of the AWT event to be recognized. The AWT interrupt signal is
generated if the tilt angle is higher than the threshold angle for a period of time equal to or
greater than the latency period.
The AWT function is based on the accelerometer sensor only and works at 26 Hz, so the
accelerometer ODR must be set at a value of 26 Hz or higher.
By default, the AWT algorithm is applied to the positive X-axis.
In order to enable the AWT function it is necessary to set to 1 both the FUNC_EN bit and the
WRIST_TILT_EN bit of CTRL10_C (19h).
The AWT interrupt signal can be driven to the INT2 interrupt pin by setting to 1 the
INT2_WRIST_TILT bit of the DRDY_PULSE_CFG_G (0Bh) register; it can also be checked
by reading the WRIST_TILT_IA bit of the FUNC_SRC2 (54h) register (it will also clear the
interrupt signal if latched).
WRIST_TILT_IA (55h) is the status register to be used to detect which axis has triggered the
AWT event (not applicable when using one axis side only).
The full description and an example is given in the dedicated application note.
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