Datasheet
MMA8652FC
Sensors
38 Freescale Semiconductor, Inc.
6.8.2 0x15: FF_MT_CFG Freefall/Motion Configuration register
This is the Freefall/Motion configuration register for setting up the conditions of the freefall or motion function.
Figure 14. FF_MT_CFG high-g and low-g threshold
Table 49.
0x15 FF_MT_CFG register (Read/Write)
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Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
ELE OAE ZEFE YEFE XEFE — — —
Table 50. FF_MT_CFG register
Bit(s) Field Description
7ELE
Event Latch Enable: Event flags are latched into FF_MT_SRC register.
ELE denotes whether the enabled event flag will to be latched into the FF_MT_SRC register or whether the event flag
status in the FF_MT_SRC will indicate the real-time status of the event.
• If ELE bit is set to 1, then the event flags are frozen when the EA bit gets set, and the event flags are cleared by
reading the FF_MT_SRC source register.
• Reading the FF_MT_SRC register clears the event flag EA and all FF_MT_SRC bits.
0 Event flag latch disabled (default)
1 Event flag latch enabled
6OAE
Motion detect / Freefall detect flag selection
Selects between Motion (logical OR combination) and Freefall (logical AND combination) detection.
0 Freefall flag (Logical AND combination) (default)
1 Motion flag (Logical OR combination)
5ZEFE
Event flag enable on Z
ZHFE enables the detection of a motion or freefall event when the measured acceleration data on Z channel is beyond
the threshold set in FF_MT_THS register.
• If ELE bit (FF_MT_CFG register) is set to 1, then new event flags are blocked from updating the FF_MT_SRC
register.
0 Event detection disabled (default)
1 Raise event flag on measured acceleration value beyond preset threshold
4 YEFE
Event flag enable on Y event
YEFE enables the detection of a motion or freefall event when the measured acceleration data on Y channel is beyond
the threshold set in FF_MT_THS register.
• If ELE bit (FF_MT_CFG register) is set to 1, then new event flags are blocked from updating the FF_MT_SRC
register.
0 Event detection disabled (default)
1 Raise event flag on measured acceleration value beyond preset threshold
3 XEFE
Event flag enable on X event
XEFE enables the detection of a motion or freefall event when the measured acceleration data on X channel is beyond
the threshold set in FF_MT_THS register.
• If ELE bit (FF_MT_CFG register) is set to 1, then new event flags are blocked from updating the FF_MT_SRC
register.
0 Event detection disabled (default)
1 Raise event flag on measured acceleration value beyond preset threshold
2–0 —
+8 g
High-g + Threshold (Motion)
Low-g Threshold (Freefall)
High-g – Threshold (Motion)
–8 g
X, Y, or Z High-g Region
X, Y, or Z High-g Region
X, Y, or Z Low-g Region
Negative
Positive
Acceleration
Acceleration