Data Sheet

MMA8452Q
Sensors
28 Freescale Semiconductor, Inc.
0x18: FF_MT_COUNT Debounce Register
This register sets the number of debounce sample counts for the event trigger.
This register sets the minimum number of debounce sample counts of continuously matching the detection condition user
selected for the freefall, motion event.
When the internal debounce counter reaches the FF_MT_COUNT value a Freefall/Motion event flag is set. The debounce
counter will never increase beyond the FF_MT_COUNT value. Time step used for the debounce sample count depends on the
ODR chosen and the Oversampling mode as shown in Table 30.
0x18: FF_MT_COUNT_Register (Read/Write)
Bit
7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
D7 D6 D5 D4 D3 D2 D1 D0
Table 29. FF_MT_COUNT Description
D[7:0]
Count value. Default value: 0000_0000
Table 30. FF_MT_COUNT Relationship with the ODR
ODR (Hz)
Max Time Range (s) Time Step (ms)
Normal LPLN HighRes LP Normal LPLN HighRes LP
800 0.319 0.319 0.319 0.319 1.25 1.25 1.25 1.25
400 0.638 0.638 0.638 0.638 2.5 2.5 2.5 2.5
200 1.28 1.28 0.638 1.28 5 5 2.5 5
100 2.55 2.55 0.638 2.55 10 10 2.5 10
50 5.1 5.1 0.638 5.1 20 20 2.5 20
12.5 5.1 20.4 0.638 20.4 20 80 2.5 80
6.25 5.1 20.4 0.638 40.8 20 80 2.5 160
1.56 5.1 20.4 0.638 40.8 20 80 2.5 160