AN3393 datasheet(70/103 Pages) STMICROELECTRONICS

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Axis mask filter

AN3393

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Axis mask filter

The axis mask filter is used to allow or prevent axes and sign triggers. It is possible to mask

in or out all 3 axes, X, Y and Z, both in a positive and negative direction. Moreover, it is also

possible to mask in or out the vector value V (defined in Section 5.3).

There are two independent mask registers (MASKA_y and MASKB_y) and two temporary

output axis masks; they are connected to the output register (OUTSy) as shown in

Figure 12: both mask registers have a corresponding temporary output mask in the internal

memory area (this area is not accessible by the user), which contains current results of the

trigger event used as the axis mask for the next comparison or output commands. The

temporary mask value is set as output when one of the output commands (such as CONT,

OUTC, OUTW, etc....) is performed. Finally, the output register is cleared by reading OUTSy

itself.

The ABS bit (unsigned/signed setting) and R_TAM bit (release temporary output mask

settings) in SETTy affect trigger events and temporary mask release.

Figure 12. Axis mask structure

7.1

Mask registers

Mask registers MASKy_A and MASKy_B are used to enable or disable mask action on the

input data (X,Y,Z,V). Data is filtered through mask: if a mask bit is set to 1, then the

corresponding axis and sign is enabled.

The default mask register is MASKy_A. However, it is possible to change the current active

mask by using the dedicated commands: SELMA (MASKy_A selected) and SELSA

(MASKy_B selected) described in Section 6.2.

AM14778V1

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