FXOS8700CQ datasheet(69/86 Pages) FREESCALE

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9.16

Magnetometer threshold function

The magnetometer threshold function works in a similar manner to the freefall/motion detection module but uses magnetic data

for the event detection instead of acceleration data. The m_ths_oae bit setting determines the logic used to evaluate the threshold

detection function for the enabled axes. With m_ths_oae = 0, the magnetic sample data for each enabled axis must be below the

threshold values specified in the MAG_THS_X/Y/Z registers for the time period specified in MAG_THS_COUNT before the event

flag is triggered. For m_ths_oae = 1, any of the enabled axes must be above the threshold values specified in the MAG_THS_X/

Y/Z registers for the time period specified in MAG_THS_COUNT before the event flag is triggered.

9.16.1

M_THS_CFG (0x52) register

Magnetic field threshold detection configuration register.

The unsigned 15-bit M_THS_X/Y/Z registers hold the threshold used for magnetic event detection. With M_THS_CFG

[m_ths_oae] = 0, the event is detected when all of the enabled axes are below or equal to their respective threshold values (AND

condition). With M_THS_CFG [m_ths_oae] = 1, the event is detected when any of the enabled axes is above or equal to their

respective threshold value (OR condition). The thresholds for each axis are applied after the magnetic data has been adjusted

by the offset values stored in the M_OFF_X/Y/Z registers when M_CTRL_REG3[m_raw] = 0.

m_ths_ele

m_ths_oae

m_ths_zefe

m_ths_yefe

m_ths_xefe

m_ths_wake_en

m_ths_int_en

m_ths_int_cfg

Figure 112. M_THS_CFG register

Table 88. M_THS_CFG bit descriptions

Field

Description

m_ths_ele

Magnetic threshold event latch enable.

0: Event flag latch disabled. Magnetic threshold events are not latched, and the event flag will change state with the real-

time status of the event detection logic.

1: Event flag latch enabled. Magnetic threshold events are latched and the event flag can only be cleared by reading the

M_THS_SRC register.

m_ths_oae

Magnetic threshold event logic selection.

0: Logical “AND” of enabled axes X, Y, and Z below threshold flags is used to detect the event.

1: Logical “OR” of enabled axes X, Y, and Z above threshold flags is used to detect the event.

m_ths_zefe

Event flag enable on Z-axis. Default value: 0

0: Z-axis event detection disabled

1: Raise event flag on measured magnetic field value above/below preset threshold for Z-axis

m_ths_yefe

Event flag enable on Y-axis. Default value: 0

0: Y-axis event detection disabled

1: Raise event flag on measured magnetic field value above/below preset threshold for Y-axis

m_ths_xefe

Event flag enable on X-axis. Default value: 0

0: X-axis event detection disabled

1: Raise event flag on measured magnetic field value above/below preset threshold for X-axis

m_ths_wake_en

0: The system excludes the magnetic threshold event flag when evaluating the Auto-Sleep/Wake function.

1: The system includes the magnetic threshold event flag when evaluating the Auto-Sleep/Wake function.

m_ths_int_en

0: Magnetic threshold interrupt is disabled.

1: Magnetic threshold interrupt is enabled.

m_ths_int_cfg

0: Magnetic threshold event flag is output on INT2 pin (logically OR'd with other INT2 interrupt events)

1: Magnetic threshold event flag is output on INT1 pin (logically OR'd with other INT1 interrupt events)

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