MMA7455L Просмотр технического описания (PDF) - Freescale Semiconductor
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MMA7455L Datasheet PDF : 35 Pages
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G
Pulse Detection
Time duration
Gth
INT pin
Time
*Note there is up to
1.6ms delay on the
interrupt signal
Time
Single Pulse Detection ($19 PDPL=0 indicating motion detection)
Time Window for 2nd pulse $1E TW=0 indicating single pulse
Figure 4. Single Pulse Detection
CASE 2: Freefall Detection: X and Y and Z < Pulse Threshold for Time > Latency Time
For freefall detection, set in pulse mode. PDPL in Register $19 =1 for “AND” freefall condition. The Pulse threshold must be set
in Register $1B and the pulse latency time window must also be set using Register $1D. All three axes must remain below the
threshold longer than the time window for the interrupt to trigger.
$1B: Pulse Detection Threshold Limit Value (Read/Write)
D7
D6
D5
D4
D3
PDTH[7]
PDTH[6]
PDTH[5]
PDTH[4]
PDTH[3]
0
0
0
0
0
D2
PDTH[2]
0
D1
PDTH[1]
0
D0
PDTH[0]
0
Reg $1B
Function
Default
$1D: Latency Time Value (Read/Write)
D7
D6
D5
LT[7]
LT[6]
LT[5]
0
0
0
D4
LT[4]
0
D3
LT[3]
0
D2
LT[2]
0
D1
LT[1]
0
D0
LT[0]
1
Reg $1D
Function
Default
Sensors
Freescale Semiconductor
Figure 5. Freefall Detection in Pulse Mode
MMA7455L
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