FXOS8700CQ datasheet(47/86 Pages) FREESCALE

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Freescale Semiconductor, Inc.

9.9.2

A_FFMT_SRC (0x16) register

Freefall/motion source register. Read-only register.

This register keeps track of the acceleration event which is triggering (or has triggered, in case of A_FFMT_CFG[a_ffmt_ele]

= 1) the event flag. In particular A_FFMT_SRC[a_ffmt_ea] is set to a logic ‘1’ when the logical combination of acceleration event

flags specified in A_FFMT_CFG register is true. This bit is used in combination with the values in CTRL_REG4[int_en_ffmt] and

CTRL_REG5[int_cfg_ffmt] register bits to generate the freefall/motion interrupts.

Table 48. A_FFMT_CFG bit descriptions

Field

Description

a_ffmt_ele

a_ffmt_ele denotes whether the enabled event flag will be latched in the A_FFMT_SRC register or the event flag status in the

A_FFMT_SRC will indicate the real-time status of the event. If a_ffmt_ele bit is set to a logic ‘1’, then the event flags are frozen

when the a_ffmt_ea bit gets set, and are cleared by reading the A_FFMT_SRC source register.

Default value: 0

0: Event flag latch disabled

1: Event flag latch enabled

a_ffmt_oae

a_ffmt_oae bit allows the selection between motion (logical OR combination of high-g X, Y, Z-axis event flags) and freefall

(logical AND combination of low-g X, Y, Z-axis event flags) detection.

Motion detect/freefall detect logic selection.

Default value: 0 (freefall flag)

0: Freefall flag(Logical AND combination of low-g X, Y, Z-axis event flags)

1: Motion flag (Logical OR combination of high-g X, Y, Z event flags)

a_ffmt_zefe

a_ffmt_zefe enables the detection of a high or low-g event when the measured acceleration data on Z-axis is above/below

the threshold set in the A_FFMT_THS register. If the a_ffmt_ele bit is set to logic ‘1’ in the A_FFMT_CFG register, new event

flags are blocked from updating the A_FFMT_SRC register.

Default value: 0

0: Event detection disabled

1: Raise event flag on measured Z-axis acceleration above/below threshold.

a_ffmt_yefe

a_ffmt_yefe enables the detection of a high or low-g event when the measured acceleration data on Y-axis is above/below

the threshold set in the A_FFMT_THS register. If the a_ffmt_ele bit is set to logic ‘1’ in the A_FFMT_CFG register, new event

flags are blocked from updating the A_FFMT_SRC register.

Default value: 0

0: Event detection disabled

1: Raise event flag on measured Y-axis acceleration above/below threshold.

a_ffmt_xefe

a_ffmt_xefe enables the detection of a high or low-g event when the measured acceleration data on X-axis is above/below

the threshold set in the A_FFMT_THS register. If the a_ffmt_ele bit is set to logic ‘1’ in the A_FFMT_CFG register, new event

flags are blocked from updating the A_FFMT_SRC register.

Default value: 0

0: Event detection disabled

1: Raise event flag on measured X-axis acceleration above/below threshold.

a_ffmt_ea

—

a_ffmt_zhe

a_ffmt_zhp

a_ffmt_yhe

a_ffmt_yhp

a_ffmt_xhe

a_ffmt_xhp

00000000

Figure 45. A_FFMT_SRC register

Table 49. A_FFMT_SRC bit descriptions

Field

Description

a_ffmt_ea

Event active flag. Default value: 0

0: No event flag has been asserted

1: One or more event flag has been asserted. See the description of the A_FFMT_CFG[a_ffmt_oae] bit to determine the

effect of the 3-axis event flags on the a_ffmt_ea bit.

a_ffmt_zhe

Z-high event flag. Default value: 0

0: Event detected

1: Z-high event has been detected

This bit always reads zero if the a_ffmt_zefe control bit is set to zero

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