Accelerometer

2009-07-25T06:20:29Z

Sushi:

The accelerometer appears to be a "KXSD9 SERIES Tri-Axis, 2g, 4g, 6g, 8g, User Selectable, Ultra Low Power Digital"
[http://www.kionix.com/accelerometers/accelerometer-KXSD9.html http://www.kionix.com/accelerometers/accelerometer-KXSD9.html]

<source lang="text">
root@castle:/sys/class/input/input5# cat name
kxsd9_accelerometer
</source>

more info:
<source lang="text">
root@castle:/sys/class/input/input5# cat uevent
PHYSDEVPATH=/class/i2c-adapter/i2c-3/3-0018
PHYSDEVBUS=i2c
PHYSDEVDRIVER=kxsd9_accelerometer
PRODUCT=18/1/1/100
NAME="kxsd9_accelerometer"
EV==9
ABS==7
MODALIAS=input:b0018v0001p0001e0100-e0,3,kra0,1,2,mlsfw
</source>

and at the very least you could adjust the low pass filter used, or the threshold for waking up:

<source lang="text">
root@castle:/sys/class/input/input5# ls -al
drwxr-xr-x 6 root root 0 Jun 11 17:47 .
drwxr-xr-x 8 root root 0 Jun 11 17:47 ..
-rw-r--r-- 1 root root 4096 Jun 11 23:58 accelerometer_filter_frequency
-rw-r--r-- 1 root root 4096 Jun 11 23:58 accelerometer_motion_wake_up_threshold
drwxr-xr-x 2 root root 0 Jun 11 23:58 capabilities
lrwxrwxrwx 1 root root 0 Jun 11 23:58 device -> ../../../class/i2c-adapter/i2c-3/3-0018
drwxr-xr-x 3 root root 0 Jun 11 23:49 event5
drwxr-xr-x 2 root root 0 Jun 11 23:58 id
lrwxrwxrwx 1 root root 0 Jun 11 23:58 input:event5 -> ../../../class/input/input5/event5
-r--r--r-- 1 root root 4096 Jun 11 23:58 modalias
-rw-r--r-- 1 root root 0 Jun 11 23:50 mode
-r--r--r-- 1 root root 4096 Jun 11 23:53 name
-r--r--r-- 1 root root 4096 Jun 11 23:58 phys
-rw-r--r-- 1 root root 4096 Jun 11 23:58 poll_interval
drwxr-xr-x 2 root root 0 Jun 11 23:58 power
lrwxrwxrwx 1 root root 0 Jun 11 23:58 subsystem -> ../../../class/input
-rw-r--r-- 1 root root 4096 Jun 11 23:58 uevent
-r--r--r-- 1 root root 4096 Jun 11 23:58 uniq
</source>

More accelerometer info

There's a library called libhidaccelerometer.so -- so it's treated as an HID class of devices. There is no dbus activity when you move the device, so this probably a much lower level service. Makes sense: you don't want zillions of dbus messages firing off whenever someone moves.

Looking in running processes, I notice /usr/bin/hidd, which references a configuration file '''/etc/hidd/HidPlugins.xml'''

In this file, two sockets are mentioned:
/var/tmp/hidd/AccelerometerCmdSocket
/var/tmp/hidd/AccelerometerEventSocket

These are UNIX DGRAM sockets, which are open on the device.

== Sample code ==
Taken from boydell's Magic 8 Ball app:

In his '''first-assistant.js''' (''... = code skips'')
<source lang="text">
...
this.controller.listen(this.controller.sceneElement, Mojo.Event.tap, this.handleTap.bind(this));
this.controller.listen(document, 'shakestart', this.handleShakeStart.bind(this));
this.controller.listen(document, 'shaking', this.handleShaking.bind(this));
this.controller.listen(document, 'shakeend', this.handleShakeEnd.bind(this));
...
FirstAssistant.prototype.handleShakeStart = function(event) {
this.setBall();
this.hideMessage();
Event.stop(event);
}

FirstAssistant.prototype.handleShaking = function(event) {
this.setBall();
this.hideMessage();
Event.stop(event);
}

FirstAssistant.prototype.handleShakeEnd = function(event) {
this.showRandomMessage();
Event.stop(event);
</source>

[[Category:Hardware]]

WebOS Internals - User contributions [en]

Accelerometer