AN4662 datasheet(31/43 Pages) STMICROELECTRONICS

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AN4662

6D/4D orientation detection

The LIS2HH12 provides advanced capability to detect the orientation of the device in

space, enabling easy implementation of an energy-saving procedure and automatic image

rotation for handheld devices.

7.1

6D orientation detection

Allows generating an Interrupt signal when one face of the device is stable in a known

direction (almost flat): six orientations of the device in space can be detected. The 6D

orientation direction function can be enabled through the AOI and 6D bits of the

IG_CFG1(2) register, in detail ZHIE, ZLIE, YHIE, YLIE, XHIE and XLIE must be set to “1” in

order to generate the interrupt in all the six possible directions. The 6D interrupt is asserted

when only one axis exceeds the selected threshold and the accelerations measured from

other two axes are lower than the threshold, while the interrupt is deasserted when more

than one axis measures acceleration that exceeds the selected threshold.

When configured for 6D function, the ZH, ZL, YH, YL, XH, and XL bits of IG_SRC1(2) give

information about the device orientation indicating which face is almost flat and in which

direction (i.e. face up or face down). Only one of the six LSB of IG_SRC1(2) could be set to

“1” when 6D detection is enabled: ZH or ZL or YH or YL or XH or XL.

In more detail:

•

ZH (YH, XH) is equal to “1” when the face perpendicular to the Z(Y,X) axis is almost

flat and the acceleration measured on the Z(Y,X) axis is positive and in the module

bigger than the threshold.

•

ZL (YL, XL) is equal to “1” when the face perpendicular to the Z(Y,X) axis is almost flat

and the acceleration measured on the Z(Y,X) axis is negative and in the module

bigger than the threshold.

There are two possible configurations for the 6D function:

•

6D movement recognition: In this configuration the interrupt is generated when the

device moves from a direction (known or unknown) to a different known direction. The

interrupt signal is active only for 1/ODR [s] then it is automatically deasserted. This

function is activated by setting the AOI-bit = 0 and 6D-bit = 1 in IG_CFG1(2) register.

IG_CFG1(2) register must be set to 0x7F in order to generate the 6D movement

interrupt in all six directions.

•

6D position recognition: In this configuration the interrupt is generated when the

device is stable in one of the six known positions; the interrupt remains active as long

as the position is maintained. This function is activated by setting the AOI-bit = 1 and

•

6D-bit = 1 in IG_CFG1(2) register. IG_CFG1(2) register must be set to 0xFF in order

to generate the interrupt in all six positions.

Referring to Figure 15: "6D movement vs. 6D position interrupt", the 6D movement line

shows the behavior of the interrupt when the device is configured for 6D movement

recognition on the X and Y positive axis (IG_CFG1(2) = 0x4A), while the 6D position line

shows the behavior of the interrupt when the device is configured for 6D position

recognition on the X and Y positive axis (IG_CFG1(2) = 0xCAh).

Referring to Figure 16: "6D recognized positions", the device has been configured for 6D

position function on the X, Y, and Z axis. Table 25: "IG_SRC1(2) register in 6D position"

shows the content of the IG_SRC1(2) register for each position.

DocID027579 Rev 1

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