LIS2DW12 datasheet(17/66 Pages) STMICROELECTRONICS

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3.2.4

Activity/Inactivity, Android stationary/motion-detection functions

The activity/inactivity function recognizes the device’s sleep state and allows reducing system power

consumption.

When the activity/inactivity function is activated by setting the INTERRUPTS_ENABLE bit in CTRL7 (3Fh) and the

SLEEP_ON bit in WAKE_UP_THS (34h), the LIS2DW12 automatically goes to 12.5 Hz ODR in the low-power

mode previously selected by the LP_MODE[1:0] bits in CTRL1 (20h) if the sleep state condition is detected and

wakes up as soon as the interrupt event has been detected, increasing the output data rate and bandwidth.

With this feature the system may be efficiently switched from low-power mode to full performance depending on

user-selectable positioning and acceleration events, thus ensuring power saving and flexibility.

The Android stationary/motion detection function only recognizes the device’s sleep state.

When the Android stationary/motion-detection function is activated by setting the STATIONARY bit in

WAKE_UP_DUR (35h), the LIS2DW12 detects acceleration below a fixed threshold but does not change either

ODR or operating mode (High-Performance mode or Low-Power mode) after sleep state detection.

The Activity/Inactivity recognition function can use the high-pass filter or the offset outputs, this choice can be

made through the USR_OFF_ON_OUT bit in CTRL7 (3Fh).

If the device is in sleep (inactivity/stationary) mode, when at least one of the axes exceeds the threshold in

WAKE_UP_THS (34h), the device goes into a sleep-to-wake state (as wake-up).

For the activity/inactivity function, the device, in a wake-up state, will return to the operating mode (HP or LP) and

ODR before sleep state detection.

Activity/Inactivity, Android stationary/motion-detection threshold and duration can be configured in the following

control registers:

WAKE_UP_THS (34h)

WAKE_UP_DUR (35h)

3.2.5

High tap/double-tap user configurability

The device embeds the possibility to select the following parameters:

•

single axis or multiple axes in TAP_THS_Z (32h)

•

axis priority in TAP_THS_Y (31h)

•

threshold value of each axis in TAP_THS_X (30h), TAP_THS_Y (31h), and TAP_THS_Z (32h)

•

max time threshold between 2 consecutive taps for double-tap recognition, min time threshold between 2

consecutive taps to detect a new tap event in INT_DUR (33h)

3.2.6

Offset management

The user can manage offset in the output or for wakeup detection using dedicated embedded hardware (see

Section 5.1 Block diagram of filters).

LIS2DW12

Functionality

DS11811 - Rev 8

page 17/66

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