Datasheet

MMA8451Q
Sensors
Freescale Semiconductor, Inc. 15
5.9 Orientation Detection
The MMA8451Q incorporates an advanced algorithm for orientation detection (ability to detect all 6 orientations) with
configurable trip points. The embedded algorithm allows the selection of the mid point with the desired hysteresis value.
The MMA8451Q Orientation Detection algorithm confirms the reliability of the function with a configurable Z-lockout angle.
Based on known functionality of linear accelerometers, it is not possible to rotate the device about the Z-axis to detect change in
acceleration at slow angular speeds. The angle at which the device no longer detects the orientation change is referred to as the
“Z-Lockout angle”. The device operates down to 14° from the flat position.
For further information on the configuration settings of the orientation detection function, including recommendations for
configuring the device to support various application use cases, refer to Freescale application note, AN4068.
Figure 8 shows the definitions of the trip angles going from Landscape to Portrait (A) and then also from Portrait to Landscape
(B).
Figure 7. Landscape/Portrait Orientation
Figure 8. Illustration of Landscape to Portrait Transition (A) and Portrait to Landscape Transition (B)
Top View
PU
Earth Gravity
Pin 1
Xout @ 0g
Yout @ -1g
Zout @ 0g
Xout @ 1g
Yout @ 0g
Zout @ 0g
Xout @ 0g
Yout @ 1g
Zout @ 0g
Xout @ -1g
Yout @ 0g
Zout @ 0g
LL
PD
LR
Side View
FRONT
Xout @ 0g
Yout @ 0g
Zout @ 1g
BACK
Xout @ 0g
Yout @ 0g
Zout @ -1g
PORTRAIT
Landscape to Portrait
90°
Trip Angle = 60°
0° Landscape
PORTRAIT
Portrait to Landscape
90°
Trip Angle = 30°
0° Landscape
(A) (B)