Datasheet
MMA8652FC
Sensors
44 Freescale Semiconductor, Inc.
6.9.3 0x1F TRANSIENT_THS register
The Transient Threshold register sets the threshold limit for the detection of the transient acceleration. The value in the
TRANSIENT_THS register corresponds to a g value, which is compared against the values of high-pass filtered data. If the high-
pass filtered acceleration value exceeds the threshold limit, an event flag is raised and the interrupt is generated (if enabled).
6.9.4 0x20 TRANSIENT_COUNT register
The TRANSIENT_COUNT sets the minimum number of debounce counts continuously matching the condition where the
unsigned value of high-pass filtered data is greater than the user-specified value of TRANSIENT_THS.
The time step for the transient detection debounce counter is set by the value of the system ODR and the Oversampling mode.
Table 62.
0x1F TRANSIENT_THS register (Read/Write)
Back to Register Address Map
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
DBCNTM THS6 THS5 THS4 THS3 THS2 THS1 THS0
Table 63. TRANSIENT_THS register
Bit(s) Field Description Notes
7 DBCNTM
Debounce counter mode selection
0 Increments or decrements debounce (default)
1 Increments or clears counter
6–0 THS[6:0]
Transient Threshold
A 7-bit unsigned number, with 0.063 g/LSB.
The maximum threshold is ±8 g.
000_0000 (default)
Even if the part is set to full scale at ±2 g (or ±4 g), this
function will still operate up to ±8 g.
Table 64.
0x20 TRANSIENT_COUNT register (Read/Write)
Back to Register Address Map
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
D7 D6 D5 D4 D3 D2 D1 D0
Table 65. TRANSIENT_COUNT register
Bit(s) Field Description
7–0 D[7:0]
Count value
0000_0000 (d
efault)
Table 66. TRANSIENT_COUNT relationship with the ODR
ODR (Hz)
Max Time Range (s) Time Step (ms)
Normal LPLN HighRes LP Normal LPLN HighRes LP
800 0.319 0.319 0.319 0.319 1.25 1.25 1.25 1.25
400 0.638 0.638 0.638 0.638 2.5 2.5 2.5 2.5
200 1.28 1.28 0.638 1.28 5 5 2.5 5
100 2.55 2.55 0.638 2.55 10 10 2.5 10
50 5.1 5.1 0.638 5.1 20 20 2.5 20
12.5 5.1 20.4 0.638 20.4 20 80 2.5 80
6.25 5.1 20.4 0.638 40.8 20 80 2.5 160
1.56 5.1 20.4 0.638 40.8 20 80 2.5 160