help:LIS302DL free fall detection

Discussion in 'The Projects Forum' started by alexpanrui, Jan 14, 2009.

  1. alexpanrui

    Thread Starter Active Member

    Feb 25, 2008
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    what is the practical use of free fall detection? I downloaded one app notes on lis302dl, in which the pseudo code of free fall detection is given. I coded it and released the sensor from certain height. According to the explanation of the pseudo code, an interrupt should be generated when free fall detected. But I was unable to receive the interrupt signal. What could go wrong?
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Which app notes? Can you provide a link?
     
  3. RiJoRI

    Well-Known Member

    Aug 15, 2007
    536
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    "What is the practical use of free fall detection?"

    (A) to idiot-proof skydiving?
    (B) to allow the military to drop supplies to troops with less time of descent and/or less drifting?

    --Rich
     
  4. davebee

    Well-Known Member

    Oct 22, 2008
    539
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    After you drop your laptop, to move the hard drive head quickly to an edge of the platter for protection before the laptop hits the ground?
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Yes that is the only (pracitcal) use that came to my mind.

    Or could be used to activate airbags when you drive off a cliff :)
     
  6. alexpanrui

    Thread Starter Active Member

    Feb 25, 2008
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    file attached.
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    I would guess that with a selection of +/- 2 & +/- 8 G's, the zero G level is actually 1 G - normal gravity. That would make the measurement relative to that, or +3/-1 G actual.
     
  8. alexpanrui

    Thread Starter Active Member

    Feb 25, 2008
    32
    0
    in the pseudo code given in the app note, a threshold and a duration have been set.And the interrupt is activated if the acceleration is below the threshold for free fall. why is so?
     
  9. alexpanrui

    Thread Starter Active Member

    Feb 25, 2008
    32
    0
    upz..............
     
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