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    SubjectRe: [ltp] IBM HDAPS Someone interested? (Userspace accelerometer viewer)
    On Sun, 3 Jul 2005, Alejandro Bonilla wrote:
    > PLEASE read the following article, it has the data of a guy that made a
    > driver in IBM for Linux and he described the driver he made.
    > http://www.almaden.ibm.com/cs/people/marksmith/tpaps.html

    Yesterday evening, I used my time here at Debconf5 constructively! ;-)

    http://www.paul.sladen.org/thinkpad-r31/aps/accelerometer-viewer.jpg (43kB)
    http://www.paul.sladen.org/thinkpad-r31/aps/accelerometer-lid-shut.jpg (27kB)

    The sensor gives us two 10-bit AD values (corresponding to 0..1 volts on the
    ADI chip), temperature (Celsius) and three status bits indicating:

    * lid open/closed
    * keyboard activity
    * nipple movement

    On the X40 I borrowed (thanks Robert McQueen), at rest the outputs hover
    around 512 (0x200). Gravity is supposed to fall off in a sine-wave during
    rotation, but I found that:

    theta = (N - 512) * 0.5

    provides a surprisingly good approximation for pitch/roll values in degrees
    in the range (-90..+90) so I think the sensor can do ~= +/-2.5G .

    http://www.paul.sladen.org/thinkpad-r31/aps/accelerometer-screenshot.png (9kB)

    -Paul

    PS. Coincidently, the name of the machine I borrowed is 'theta'...
    --
    Mostly it snows here. Helsinki, FI



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