APS(4) FreeBSD 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 <
[email protected]>.
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. Possible
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.
FreeBSD 14.1-RELEASE-p8 July 13, 2011 FreeBSD 14.1-RELEASE-p8