aps(4) - NetBSD Manual Pages

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APS(4)                  NetBSD Kernel Interfaces Manual                 APS(4)


NAME

     aps -- ThinkPad Active Protection System accelerometer


SYNOPSIS

     aps0 at isa? port 0x1600


DESCRIPTION

     The aps driver provides support for several sensors found in some
     ThinkPad laptops.

     The sensors currently exposed via the envsys(4) interface are:

           Sensor            Units        Typical Use
           x-acceleration    integer      X-axis acceleration
           y-acceleration    integer      Y-axis acceleration
           x-variable        integer      Weighted X acceleration?
           y-variable        integer      Weighted Y acceleration?
           temperature 1     degC         Unknown temperature
           temperature 2     degC         Unknown temperature
           keyboard active   boolean      Keyboard activity
           mouse active      boolean      Mouse activity
           lid open          boolean      Lid state


SEE ALSO

     envsys(4), hpacel(4), thinkpad(4), envstat(8)


HISTORY

     The aps driver first appeared in OpenBSD 3.8 and was then ported to
     NetBSD 5.0.


AUTHORS

     The aps driver was written by Jonathan Gray <jsg@openbsd.org>.


CAVEATS

     Few issues can be mentioned.

     ·   The aps driver does not maintain state and subsequently does not take
         evasive action when it thinks the hard drive is in danger.  Possible
         actions would include spinning down the hard drive in case excessive
         tremor is detected by the sensors.

     ·   The Y axis on X40 and possibly other models seems to be inverted.  It
         is unknown how to distinguish between different versions of the
         accelerometer to compensate for this in the driver at this time.

     ·   The sensor values are refreshed every 0.5 seconds.  Because no pro-
         tection measures are taken, this is unnecessary and may have a nega-
         tive effect on battery life.

     ·   As IBM provides no documentation, it is not known what all the avail-
         able sensors are used for.

NetBSD 9.0                       July 13, 2011                      NetBSD 9.0