AN2989

Interrupt generation

Doc ID 15761 Rev 1

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Figure 8.

Free-fall, wakeup interrupt generator

The threshold module which is used by the system to detect free-fall or inertial wakeup

events is defined by the INTx_THS registers. The threshold value is expressed over 7 bits as

an unsigned number and is symmetrical around the zero-g level. XH (YH, ZH) is true when

the unsigned acceleration value of the X (Y, Z) channel is higher than INTx_THS. Similarly,

XL, (YL, ZL) low is true when the unsigned acceleration value of the X (Y, Z) channel is

lower than INTx_THS. Refer to Figure 9 for additional details.

Figure 9.

FF_WU_CFG high and low