MMA685X datasheet(17/52 Pages) FREESCALE

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Freescale Semiconductor, Inc.

MMA685x

3.1.8.2

Arming Pulse Stretch (APS[1:0])

The APS[1:0] bit sets the programmable pulse stretch time for the arming outputs. Refer to Section 3.8.9 for more details re-

garding the arming function.

3.1.8.3

Arming Window Size (AWS_x[1:0])

The AWS_x[1:0] bit has a different function depending on the state of the A_CFG bits in the DEVCFG register.

If the arming function is set to moving average mode, the AWS bits set the number of acceleration samples used for the arming

function moving average. The number of samples is set independently for polarity. If the arming function is set to count mode,

the AWS bits set the sample count limit for the arming function. The sample count limit is set independently.

Refer to Section 3.8.9 for more details regarding the arming function.

Table 13. Arming Pulse Stretch Definitions

APS[1]

APS[0]

Pulse Stretch Time(1) (Typical Oscillator)

1.Pulse stretch times are derived from the internal oscillator, so the tolerance on this oscillator applies.

0 mS

16.256 ms - 16.384 ms

65.408 ms - 65.536 ms

261.888 ms - 262.016 ms

Table 14. Positive Arming Window Size Definitions (Moving Average Mode)

AWS_P[1]

AWS_P[0]

Positive Window Size

Table 15. Negative Arming Window Size Definitions (Moving Average Mode)

AWS_N[1]

AWS_N[0]

Negative Window Size

Table 16. Arming Count Limit Definitions (Count Mode)

AWS_N[1]

AWS_N[0]

AWS_P[1]

AWS_P[0]

Sample Count Limit

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