MMA8450QT Freescale Semiconductor, MMA8450QT Datasheet - Page 33

• Manufacturer Part Number: MMA8450QT
• Description: Board Mount Accelerometers 12bit 3-Axis FIFO HPF PL
• Manufacturer: Freescale Semiconductor

Specifications of MMA8450QT

• Sensing Axis: X, Y, Z
• Acceleration: 2 g, 4 g, 8 g
• Digital Output - Number Of Bits: 12 bit
• Supply Voltage (max): 1.89 V
• Supply Voltage (min): 1.71 V
• Supply Current: 3 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Shutdown: Yes
• Sensitivity: 0.976 mg/digit, 1.953 mg/digit, 3.906 mg/digit
• Package / Case: QFN-16
• Output Type: Digital
• Package Type: QFN
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3mm
• Product Height (mm): 1mm
• Product Length (mm): 3mm
• Mounting: Surface Mount
• Pin Count: 16
• Acceleration Range: ± 2g, ± 4g, ± 8g
• No. Of Axes: 3
• Ic Interface Type: I2C, Serial
• Sensor Case Style: QFN
• No. Of Pins: 16
• Supply Voltage Range: 1.71V To 1.89V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 34. FF_MT_SRC_1 Description
0x24 FF_MT_SRC_1 Register
register being set to 1) the event flag. In particular EA is set to a logic 1 when the logical combination of acceleration events flags
specified in FF_MT_CFG_1 register is true. This bit is used in combination with the values in INT_EN_FF_MT_1 and
INT_CFG_FF_MT_1 register to generate the Freefall/Motion interrupts.
preset threshold value defined in the FF_MT_THS_1 register.
than the preset threshold value defined in the FF_MT_THS_1 register.
the register must be read immediately. The EA bit will remain high until the source register is read.
0x25: FF_MT_THS_1 Freefall and Motion Threshold 1 Register
of 0 to 127.
Therefore:
12
no longer true
might impede the detection of the event.
0x24: FF_MT_SRC_ Freefall and Motion Source Register (0x24) (Read Only)
Table 35. FF_MT_THS_1 Description
Sensors
Freescale Semiconductor
0x25 FF_MT_THS_1 Register (Read/Write)
This register keeps track of the acceleration event which is triggering (or has triggered, in case of ELE bit in FF_MT_CFG_1
An X,Y, or Z high or an X,Y, and Z high event is true when the acceleration value of the X or Y or Z axes is higher than the
Conversely X,Y, or Z high or an X,Y, and Z low event is true when the acceleration value of the X and Y and Z axes are lower
When the ELE bit is set, only the EA bit is latched. The other bits are not latched. To see the events that have been detected,
The minimum threshold resolution is dependent on the selected acceleration g range and the threshold register has a range
When DBCNTM bit is a logic ‘1’, the debounce counter is cleared to 0 whenever the event of interest is no longer true
Decrementing of the debounce counter acts as a median filter enabling the system to filter out irregular spurious events which
part b) while if the DBCNTM bit is set a logic ‘0’ the debounce counter is decremented by 1 whenever the event of interest is
DBCNTM
•
•
•
DBCNTM
ZHE
YHE
XHE
ZLE
YLE
XLE
THS[6:0]
EA
Bit 7
Bit 7
—
If the selected acceleration g range is 8g mode (FS = 11), the minimum threshold resolution is 0.063g/LSB. The maximum
value is 8g.
If the selected acceleration g range is 4g mode (FS = 10), the minimum threshold resolution is 0.0315g/LSB. The
maximum value is 4g.
If the selected acceleration g range is 2g mode (FS = 01), the minimum threshold resolution is 0.01575g/LSB. The
maximum value is 2g.
Event Active Flag. Default value: 0.
0: No event flag has been asserted; 1: one or more event flags have been asserted.
Z High Event Flag. Default value: 0.
0: No Z High event detected, 1: Z High event has been detected
Z Low Event Flag. Default value: 0.
0: No Z Low event detected, 1: Z Low event has been detected
Y High Event Flag. Default value: 0.
0: No Y High event detected, 1: Y High event has been detected
Y Low Event Flag. Default value: 0.
0: No Y Low event detected, 1: Y Low event has been detected
X High Event Flag. Default value: 0.
0: No X High event detected, 1: X High event has been detected
X Low Event Flag. Default value: 0.
0: No X Low event detected, 1: X Low event has been detected
(Figure 12
Debounce counter mode selection. Default value: 0.
0: increments or decrements debounce, 1: increments or clears counter.
Freefall /Motion Threshold: Default value: 000 0000
THS6
Bit 6
Bit 6
EA
part c) until the debounce counter reaches 0 or the event of interest becomes active.
THS5
Bit 5
ZHE
Bit 5
THS4
Bit 4
Bit 4
ZLE
THS3
Bit 3
Bit 3
YHE
THS2
Bit 2
Bit 2
YLE
THS1
Bit 1
Bit 1
XHE
MMA8450Q
THS0
Bit 0
Bit 0
XLE
(Figure
33