MMA8652FC datasheet(39/65 Pages) NXP

39 / 65 page

MMA8652FC

Sensors

Freescale Semiconductor, Inc.

6.8.3

0x16: FF_MT_SRC Freefall/Motion Source register

The Freefall/Motion Source register keeps track of the acceleration event that is triggering (or has triggered, if ELE bit in

FF_MT_CFG register is set to 1) the event flag. In particular, EA is set to 1 when the logical combination of acceleration events

flags specified in FF_MT_CFG register is true. This EA bit is used in combination with the values in INT_EN_FF_MT and

INT_CFG_FF_MT register bits to generate the freefall/motion interrupts.

•

An X,Y, or Z motion is true when the acceleration value of the X or Y or Z channel is higher than the preset threshold value

defined in the FF_MT_THS register.

•

An X, Y, and Z low event is true when the acceleration value of the X and Y and Z channel is lower than or equal to the preset

threshold value defined in the FF_MT_THS register.

Table 51. 0x16: FF_MT_SRC Freefall/Motion Source register (Read-Only)

Back to Register Address Map

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

—

ZHE

ZHP

YHE

YHP

XHE

XHP

Table 52. Freefall/Motion Source register

Bit(s)

Field

Description

7EA

Event Active flag

0 No event flag has been asserted (default)

1 One or more event flags has been asserted.

See the description of the OAE bit to determine the effect of the 3-axis event flags on the EA bit.

6—

5ZHE

Z-Motion flag

ZHE bit always reads zero if the ZEFE control bit is set to zero.

0 No Z motion event detected (default)

1 Z motion has been detected

4ZHP

Z-Motion Polarity Flag

ZHP bit always reads zero if the ZEFE control bit is set to zero.

0 Z event was positive g (default)

1 Z event was negative g

3YHE

Y-Motion Flag

YHE bit always reads zero if the YEFE control bit is set to zero.

0 No Y motion event detected (default)

1 Y motion has been detected

2YHP

Y-Motion Polarity Flag

YHP bit always reads zero if the YEFE control bit is set to zero.

0 Y event detected was positive g (default)

1 Y event was negative g

1XHE

X-Motion Flag

XHE bit always reads zero if the XEFE control bit is set to zero.

0 No X motion event detected (default)

1 X motion has been detected

0XHP

X-Motion Polarity Flag

XHP bit always reads zero if the XEFE control bit is set to zero.

0 X event was positive g (default)

1 X event was negative g

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