Datasheet

Sensors
Freescale Semiconductor, Inc. 12
MMA7660FC
Orientation Detection
Orientation Detection Logic
MMA7660FC gives the customer the capability to do orientation detection for such applications as Portrait/Landscape in
Mobile Phone/PDA/ PMP. The tilt orientation of the device is in 3 dimensions and is identified in its last known static position. This
enables a product to set its display orientation appropriately to either portrait/landscape mode, or to turn off the display if the
product is placed upside down. The sensor provides six different positions including: Left, Right, Up, Down, Back, and Front,
shown in Table 7. In Active Mode the data is processed and updates the orientation positions in the TILT (0x03) register. At each
measurement interval, it computes new values for Left, Right, Up, Down, Back, and Front but it does not automatically update
these bits in the TILT (0x03) register. These values are updated depending on the debounce filter settings (SR Register 0x08)
configured by the customer.
In order to give the customer the ability to configure the debounce filter, specific to there application, they can change the
following bits in the SR (0x08) register, FILT [2:0]. Please see below for a more detailed explanation of how the FILT [2:0] works
in conjunction with updating the TILT (0x03) register:
• If FILT [2:0] = 000, then the new values for Left, Right, Up, Down, Back, and Front are updated in the TILT (0x03) register
(PoLa [2:0] and BaFro [1:0]) after every reading without any further analysis.
• If FILT [2:0] = 001 – 111, then the sensor requires the computed values for Left, Right, Up, Down, Back, and Front to be the
same from 1-7 consecutive readings (depending on the value in FILT [2:0], before updating the values stored in TILT (0x03)
register (PoLa [2:0] and BaFro [1:0]). The debounce counter is reset after a mismatched reading or the TILT (0x03) register
is updated (if the orientation condition is met).
Figure 6. Orientation Detection Logic in 3-Dimensional Space
Table 7. Orientation Detection Logic of when Interrupt will Occur
Orientation Xg Yg Zg
Shake |X| > +1.3g or |Y| > +1.3g or |Z| > +1.3g
Up |Z| < 0.8g and |X| > |Y| and X < 0
Down |Z| < 0.8g and |X| > |Y| and X > 0
Right |Z| < 0.8g and |Y| > |X| and Y < 0
Left |Z| < 0.8g and |Y| > |X| and Y > 0
Back Z < -0.25g
Front Z > 0.25g
Down
Up
Front
Back
Right
Left
Down
Up
Front
Back
Right
Left