PMMA7450LR2 Freescale Semiconductor, Inc, PMMA7450LR2 Datasheet - Page 6

• Manufacturer Part Number: PMMA7450LR2
• Description: ?2g/?4g/?8g Three Axis Low-g Digital Output Accelerometer
• Manufacturer: Freescale Semiconductor, Inc

Measurement Mode
all three axes enabled. The g-range for 2g, 4g, or 8g are
selectable with 8-bit data and the g-range of 8g is selectable
with 10-bit data. The sample rate during measurement mode
is 125 Hz. Therefore, when a conversion is complete
(signaled by the DRDY flag), the next measurement will be
ready.
Level Detection Mode
thresholds for an acceleration signal level for the combinations of x and y or x, y, and z is enabled. This is used for motion detec-
tion where the threshold can be user set depending on the application or user specific requirements. When a motion event is
detected, one of the interrupt pins (INT1 or INT2) will output a logic high output signaling the event is detected.
Setting for Motion Detection
Register 2 (Address: $19) to 0. When the output value of one of the enabled axes exceeds the threshold limit value, either INT1
or INT2 pin will output a logic High indicating the event was detected.
Assigning and Clearing the Interrupt Pins
INT pin or register bit will not be cleared until the respective clear bit (CLRINT1 or CLRINT2) in Interrupt Latch Reset Register
(Address: $17) is set. CLRINT1 and CLRINT2 should be cleared before starting next detection. Otherwise, INT pin or register will
not set.
NOTE: Measurement period and bandwidth for level detection is different from data output rate and the bandwidth of
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MMA7450L
During measurement mode, continuous measurements on
In level detection mode, the measurements for x, y and z are all enabled with 2g/4g and 8g range available.The detection of
To configure the MMA7450L for motion detection, after all three axes are enabled for detection, set the LDPOL bit in Control
Threshold limit value is common for all three axes. Positive/negative and absolute value option is available
INT1/INT2 pin assignment for level detection is controlled by Control Register 1 (Address:$18).
Detection status is able to be monitored by Detection Source Register (Address:$0A). Once the configured event is detected,
INTPIN:
– If LDPOL = 0 and all three axes are enabled for detection
– When the specified motion condition is detected, INT1 or INT2 will output a Logic high
– “XOUT ≥Threshold” or “YOUT ≥Threshold” or
“ZOUT ≥Threshold”
“measurement.” Please refer to Functional Parameter for Detection for more information.
0:INT1 will be used for event
1:INT2 will be used for event
LEVEL DETECTION MODE
logic high level is output to the DRDY pin, indicating
“Measurement data is ready.” The DRDY status can be
monitored by the DRDY bit in Status Register (Address: $09).
The DRDY pin is kept high until one of the three Output Value
Registers are read. If the next measurement data is written
before the previous data is read, the DOVR bit in the Status
Register will be set. Also note that In measurement mode,
level detection mode and pulse detection mode are not
available.
When measurements on all three axes are complete, a
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