MMA7456LT Freescale Semiconductor, MMA7456LT Datasheet - Page 12

• Manufacturer Part Number: MMA7456LT
• Description: Board Mount Accelerometers 3-AXIS DIGTL 12C&SP1
• Manufacturer: Freescale Semiconductor
• Series: -r

Specifications of MMA7456LT

• Sensing Axis: X, Y, Z
• Acceleration: 2 g, 4 g, 8 g
• Sensitivity: 64 count/g, 32 count/g, 16 count/g
• Package / Case: LGA-14
• Output Type: Digital
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.4 V
• Supply Current: 400 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Axis: X, Y, Z
• Acceleration Range: ± 2g, 4g, 8g
• Voltage - Supply: 2.4 V ~ 3.6 V
• Bandwidth: 6kHz - XY, 3.4kHz - Z
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

$1B: Pulse Detection Threshold Limit Value (Read/Write)
PULSE DETECTION
There are two interrupt pins available for detection of level and pulse conditions. The pulse detection has several timing windows
associated with it. A single pulse and a double pulse can be detected. Also freefall can be detected. The interrupt pins can be
assigned to detect the first pulse on one interrupt and the second pulse on the other interrupt. This is explained on
under the
By default all three axes are enabled and the detection range is 8g only. X and/or Y and/or Z can be disabled. There is a choice
between doing a detection for Motion detection vs. doing a detection for Freefall.
$18: Control 1 (Read/Write): Disable X, Y or Z for Pulse Detection
This allows the user to define how many axes to use for detection. All axes are enabled by default. To disable write 1
XDA: Disable X
YDA: Disable Y
ZDA: Disable Z.
$19: Control 2 (Read/Write): Motion Detection (OR condition) or Freefall Detection (AND condition)
PDPL
0: Pulse detection polarity is positive and detecting condition is OR 3 axes.
1: Pulse detection polarity is negative and detecting condition is AND 3 axes.
CASE 1: Single Pulse Motion Detection: X or Y or Z > Pulse Threshold for Time < Pulse Duration
For motion detection with single pulse the device must be in pulse mode. PDPL in Register $19 =0 for “OR” motion condition.
The Pulse threshold must be set in Register $1B and the pulse duration time window must also be set using Register $1C. The
pulse must be detected before the time window closes for the interrupt to trigger.
Sensors
Freescale Semiconductor
$1C: Pulse Duration Value (Read/Write)
PDTH[7]
DFBW
PD[7]
D7
D7
D7
D7
0
--
0
0
0
Assigning, Clearing & Detecting Interrupts
PDTH[6]
THOPT
PD[6]
D6
D6
D6
D6
0
--
0
0
0
PDTH[5]
PD[5]
ZDA
D5
D5
D5
D5
0
--
0
0
0
PDTH[4]
PD[4]
YDA
D4
D4
D4
D4
0
--
0
0
0
section.
PDTH[3]
PD[3]
XDA
D3
D3
D3
D3
--
0
0
0
0
INTREG[1]
PDTH[2]
DRVO
PD[2]
D2
D2
D2
D2
0
0
0
0
INTREG[0]
PDTH[1]
PDPL
PD[1]
D1
D1
D1
D1
0
0
0
0
PDTH[0]
INTPIN
PD[0]
LDPL
D0
D0
D0
D0
1
0
0
0
Page
MMA7456L
Reg $1C
Function
Reg $19
Function
Reg $1B
Function
Reg $18
Function
Default
Default
Default
Default
15,
12