Freescale Semiconductor FRDM-FXS-MULTI 데이터 시트
FXOS8700CQ
Sensors
56
Freescale Semiconductor, Inc.
10.8.5
PL_THS_REG (0x14) register
Portrait to landscape trip threshold registers.
10.9
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.
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.
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_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
event (low-g/high-g). When A_FFMT_CFG[a_ffmt_ele] = 1, the freefall or motion event is latched and the
Table 73. PL_THS_REG register
pl_ths[4:0]
hys[2:0]
0b0_1000
0b100
Table 74. Threshold angle lookup table
pl_ths[4:0] value
Threshold angle (approx.)
0x07
15°
0x09
20°
0x0C
30°
0x0D
35°
0x0F
40°
0x10
45°
0x13
55°
0x14
60°
0x17
70°
0x19
75°
Table 75. Trip angles versus hysteresis settings
hys[2:0] value
Landscape to Portrait trip angle
Portrait to Landscape trip angle
0b000
45°
45°
0b001
49°
41°
0b010
52°
38°
0b011
56°
34°
0b100
59°
31°
0b101
62°
28°
0b110
66°
24°
0b111
69°
21°
Table 76. Portrait/Landscape ideal orientation definitions
Position
Description
PU
y ~ -1 g, x ~ 0
PD
y ~ +1 g, x ~ 0
LR
y ~ 0, x ~ +1 g
LL
y ~ 0, x ~ -1 g