Datasheet
MMA8652FC
Sensors
42 Freescale Semiconductor, Inc.
6.9 Transient configuration and status registers
For more information about the uses of the transient function, see application note AN4083, Data Manipulation and Basic
Settings for Xtrinsic MMA865xFC Accelerometers. This Transient (HPF) acceleration detection function is similar to the motion
detection function, except that high-pass filtered data is compared.
There is an option to disable the high-pass filter through the function. In this case, the behavior is the same as the motion
detection. This allows for the device to have two motion detection functions.
6.9.1 0x1D: Transient_CFG register
The transient detection mechanism can be configured to raise an interrupt when the magnitude of the high-pass filtered
acceleration threshold is exceeded. The TRANSIENT_CFG register is used to enable the transient interrupt generation
mechanism for the three axes (X, Y, Z) of acceleration. There is also an option to bypass the high-pass filter. When the high-pass
filter is bypassed, the function behaves similar to the motion detection.
Table 58.
0x1D TRANSIENT_CFG register (Read/Write)
Back to Register Address Map
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
— — — ELE ZTEFE YTEFE XTEFE HPF_BYP
Table 59. TRANSIENT_CFG register
Bit(s) Field Description Notes
7–5 — Could be 0 or 1.
4ELE
Transient event flags are latched into the TRANSIENT_SRC
register.
Reading of the TRANSIENT_SRC register clears the event flag.
0 Event flag latch disabled (default)
1 Event flag latch enabled
3 ZTEFE
Event flag enable for Z-transient acceleration greater than a
transient threshold event.
0 Event detection disabled (default)
1 Raise event flag on measured acceleration delta
value that is greater than a transient threshold.
2YTEFE
Event flag enable for Y-transient acceleration greater than a
transient threshold event.
1XTEFE
Event flag enable for X-transient acceleration greater than
a transient threshold event.
0 HPF_BYP
Bypass high-pass filter
0 Data to transient acceleration detection block is through HPF
(default)
1 Data to transient acceleration detection block is NOT through
HPF (similar to motion detection function)