]>
Commit | Line | Data |
---|---|---|
455fbdd3 | 1 | Kernel driver lis3lv02d |
2b872903 | 2 | ======================= |
455fbdd3 PM |
3 | |
4 | Supported chips: | |
5 | ||
6 | * STMicroelectronics LIS3LV02DL and LIS3LV02DQ | |
7 | ||
2b872903 | 8 | Authors: |
455fbdd3 PM |
9 | Yan Burman <burman.yan@gmail.com> |
10 | Eric Piel <eric.piel@tremplin-utc.net> | |
11 | ||
12 | ||
13 | Description | |
14 | ----------- | |
15 | ||
219beb29 PM |
16 | This driver provides support for the accelerometer found in various HP |
17 | laptops sporting the feature officially called "HP Mobile Data | |
2b872903 | 18 | Protection System 3D" or "HP 3D DriveGuard". It detects automatically |
219beb29 PM |
19 | laptops with this sensor. Known models (for now the HP 2133, nc6420, |
20 | nc2510, nc8510, nc84x0, nw9440 and nx9420) will have their axis | |
21 | automatically oriented on standard way (eg: you can directly play | |
22 | neverball). The accelerometer data is readable via | |
455fbdd3 PM |
23 | /sys/devices/platform/lis3lv02d. |
24 | ||
25 | Sysfs attributes under /sys/devices/platform/lis3lv02d/: | |
26 | position - 3D position that the accelerometer reports. Format: "(x,y,z)" | |
219beb29 PM |
27 | calibrate - read: values (x, y, z) that are used as the base for input |
28 | class device operation. | |
29 | write: forces the base to be recalibrated with the current | |
2b872903 | 30 | position. |
455fbdd3 PM |
31 | rate - reports the sampling rate of the accelerometer device in HZ |
32 | ||
33 | This driver also provides an absolute input class device, allowing | |
34 | the laptop to act as a pinball machine-esque joystick. | |
35 | ||
ef2cfc79 PM |
36 | Another feature of the driver is misc device called "freefall" that |
37 | acts similar to /dev/rtc and reacts on free-fall interrupts received | |
38 | from the device. It supports blocking operations, poll/select and | |
39 | fasync operation modes. You must read 1 bytes from the device. The | |
40 | result is number of free-fall interrupts since the last successful | |
41 | read (or 255 if number of interrupts would not fit). | |
42 | ||
43 | ||
455fbdd3 PM |
44 | Axes orientation |
45 | ---------------- | |
46 | ||
47 | For better compatibility between the various laptops. The values reported by | |
48 | the accelerometer are converted into a "standard" organisation of the axes | |
49 | (aka "can play neverball out of the box"): | |
50 | * When the laptop is horizontal the position reported is about 0 for X and Y | |
2b872903 | 51 | and a positive value for Z |
455fbdd3 | 52 | * If the left side is elevated, X increases (becomes positive) |
219beb29 PM |
53 | * If the front side (where the touchpad is) is elevated, Y decreases |
54 | (becomes negative) | |
455fbdd3 PM |
55 | * If the laptop is put upside-down, Z becomes negative |
56 | ||
219beb29 PM |
57 | If your laptop model is not recognized (cf "dmesg"), you can send an |
58 | email to the authors to add it to the database. When reporting a new | |
59 | laptop, please include the output of "dmidecode" plus the value of | |
60 | /sys/devices/platform/lis3lv02d/position in these four cases. | |
455fbdd3 | 61 | |
2b872903 PM |
62 | Q&A |
63 | --- | |
64 | ||
65 | Q: How do I safely simulate freefall? I have an HP "portable | |
66 | workstation" which has about 3.5kg and a plastic case, so letting it | |
67 | fall to the ground is out of question... | |
68 | ||
69 | A: The sensor is pretty sensitive, so your hands can do it. Lift it | |
70 | into free space, follow the fall with your hands for like 10 | |
71 | centimeters. That should be enough to trigger the detection. |