72 lines
2.7 KiB
Plaintext
72 lines
2.7 KiB
Plaintext
|
Kernel driver lis3lv02d
|
||
|
|
=======================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
|
||
|
|
* STMicroelectronics LIS3LV02DL and LIS3LV02DQ
|
||
|
|
|
||
|
|
Authors:
|
||
|
|
Yan Burman <burman.yan@gmail.com>
|
||
|
|
Eric Piel <eric.piel@tremplin-utc.net>
|
||
|
|
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This driver provides support for the accelerometer found in various HP
|
||
|
|
laptops sporting the feature officially called "HP Mobile Data
|
||
|
|
Protection System 3D" or "HP 3D DriveGuard". It detects automatically
|
||
|
|
laptops with this sensor. Known models (for now the HP 2133, nc6420,
|
||
|
|
nc2510, nc8510, nc84x0, nw9440 and nx9420) will have their axis
|
||
|
|
automatically oriented on standard way (eg: you can directly play
|
||
|
|
neverball). The accelerometer data is readable via
|
||
|
|
/sys/devices/platform/lis3lv02d.
|
||
|
|
|
||
|
|
Sysfs attributes under /sys/devices/platform/lis3lv02d/:
|
||
|
|
position - 3D position that the accelerometer reports. Format: "(x,y,z)"
|
||
|
|
calibrate - read: values (x, y, z) that are used as the base for input
|
||
|
|
class device operation.
|
||
|
|
write: forces the base to be recalibrated with the current
|
||
|
|
position.
|
||
|
|
rate - reports the sampling rate of the accelerometer device in HZ
|
||
|
|
|
||
|
|
This driver also provides an absolute input class device, allowing
|
||
|
|
the laptop to act as a pinball machine-esque joystick.
|
||
|
|
|
||
|
|
Another feature of the driver is misc device called "freefall" that
|
||
|
|
acts similar to /dev/rtc and reacts on free-fall interrupts received
|
||
|
|
from the device. It supports blocking operations, poll/select and
|
||
|
|
fasync operation modes. You must read 1 bytes from the device. The
|
||
|
|
result is number of free-fall interrupts since the last successful
|
||
|
|
read (or 255 if number of interrupts would not fit).
|
||
|
|
|
||
|
|
|
||
|
|
Axes orientation
|
||
|
|
----------------
|
||
|
|
|
||
|
|
For better compatibility between the various laptops. The values reported by
|
||
|
|
the accelerometer are converted into a "standard" organisation of the axes
|
||
|
|
(aka "can play neverball out of the box"):
|
||
|
|
* When the laptop is horizontal the position reported is about 0 for X and Y
|
||
|
|
and a positive value for Z
|
||
|
|
* If the left side is elevated, X increases (becomes positive)
|
||
|
|
* If the front side (where the touchpad is) is elevated, Y decreases
|
||
|
|
(becomes negative)
|
||
|
|
* If the laptop is put upside-down, Z becomes negative
|
||
|
|
|
||
|
|
If your laptop model is not recognized (cf "dmesg"), you can send an
|
||
|
|
email to the authors to add it to the database. When reporting a new
|
||
|
|
laptop, please include the output of "dmidecode" plus the value of
|
||
|
|
/sys/devices/platform/lis3lv02d/position in these four cases.
|
||
|
|
|
||
|
|
Q&A
|
||
|
|
---
|
||
|
|
|
||
|
|
Q: How do I safely simulate freefall? I have an HP "portable
|
||
|
|
workstation" which has about 3.5kg and a plastic case, so letting it
|
||
|
|
fall to the ground is out of question...
|
||
|
|
|
||
|
|
A: The sensor is pretty sensitive, so your hands can do it. Lift it
|
||
|
|
into free space, follow the fall with your hands for like 10
|
||
|
|
centimeters. That should be enough to trigger the detection.
|