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MMA8451Q
Sensors
16 Freescale Semiconductor, Inc.
Figure 9 illustrates the Z-angle lockout region. When lifting the device upright from the flat position it will be active for
orientation detection as low as14° from flat. This is user configurable. The default angle is 29° but it can be set as low as 14°.
.
Figure 9. Illustration of Z-Tilt Angle Lockout Transition
5.10 Interrupt Register Configurations
There are seven configurable interrupts in the MMA8451Q: Data Ready, Motion/Freefall, Tap (Pulse), Orientation, Transient,
FIFO and Auto-SLEEP events. These seven interrupt sources can be routed to one of two interrupt pins. The interrupt source
must be enabled and configured. If the event flag is asserted because the event condition is detected, the corresponding interrupt
pin, INT1 or INT2, will assert.
Figure 10. System Interrupt Generation Block Diagram
5.11 Serial I
2
C Interface
Acceleration data may be accessed through an I
2
C interface thus making the device particularly suitable for direct interfacing
with a microcontroller. The MMA8451Q features an interrupt signal which indicates when a new set of measured acceleration
data is available thus simplifying data synchronization in the digital system that uses the device. The MMA8451Q may also be
configured to generate other interrupt signals accordingly to the programmable embedded functions of the device for Motion,
Freefall, Transient, Orientation, and Tap.
The registers embedded inside the MMA8451Q are accessed through the I
2
C serial interface (Table 9). To enable the I
2
C
interface, VDDIO line must be tied high (i.e., to the interface supply voltage). If VDD is not present and VDDIO is present, the
UPRIGHT
NORMAL
90°
Z-LOCK = 29°
0° FLAT
DETECTION
REGION
LOCKOUT
REGION