FXLS8471Q Datasheet, PDF (49/75 Pages) Freescale Semiconductor, Inc – Linear Accelerometer

10.7.5 PL_THS_REG (0x14) register
Portrait to landscape trip threshold registers.
Table 70. PL_THS_REG register
pl_ths[4:0]
5’b01000
Table 71. Threshold angle lookup table
pl_ths[4:0] value
0x07
0x09
0x0C
0x0D
0x0F
0x10
0x13
0x14
0x17
0x19
Threshold angle (approx.)
15°
20°
30°
35°
40°
45°
55°
60°
70°
75°
hys[2:0]
3’b100
Table 72. Trip angles versus hysteresis settings
hys[2:0] value
0
1
2
3
4
5
6
7
Landscape to Portrait trip angle
45°
49°
52°
56°
59°
62°
66°
69°
Portrait to Landscape trip angle
45°
41°
38°
34°
31°
28°
24°
21°
Table 73. Portrait/Landscape ideal orientation definitions
Position
PU
PD
LR
LL
Description
y ~ -1 g, x ~ 0
y ~ +1 g, x ~ 0
y ~ 0, x ~ +1 g
y ~ 0, x ~ -1 g
10.8 Freefall and Motion detection
The Freefall/Motion detection block can be configured to detect low-g (freefall) or high-g (motion) events utilizing the
A_FFMT_CFG[a_ffmt_oae] bit.
In low-g detect mode (A_FFMT_CFG[a_ffmt_oae] = 0) a low-g condition will need to occur on all enabled axes (ex. X, Y and Z)
for the A_FFMT_SRC[a_ffmt_ea] bit to be affected. And, in high-g detect mode (A_FFMT_CFG[a_ffmt_oae] = 1) a high-g
condition occurring in any of the enabled axes (ex. X, Y or Z) will suffice to affect the A_FFMT_SRC[a_ffmt_ea] bit.
The detection threshold(s) are programed in register 0x17 (A_FFMT_THS) for common threshold operation, and 0x73-0x78
(A_FFMT_THS_X/Y/Z) for individual axis threshold operation.
A_FFMT_CFG[a_ffmt_ele] bit determines the behavior of A_FFMT_SRC[a_ffmt_ea] bit in response to the desired acceleration
event (low-g/high-g). When A_FFMT_CFG[a_ffmt_ele] = 1, the freefall or motion event is latched and the
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