APS(4)							   BSD 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.

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

     o	 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.

     o	 The sensor values are refreshed every 0.5 seconds.  Because no protection measures are taken, this is unnecessary and may have a negative
	 effect on battery life.

     o	 As IBM provides no documentation, it is not known what all the available sensors are used for.

BSD
								   July 13, 2011							       BSD