Accelerometers - Revision history

imported_>amigadave: fix double redirect

2010-06-16T14:12:00Z

fix double redirect

← Older revision		Revision as of 14:12, 16 June 2010
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	#REDIRECT [[N900 ~~Hardware Accelerometer~~]]		#REDIRECT [[N900 accelerometer]]

imported_>amigadave: redirect to N900 Hardware Accelerometer

2010-06-14T13:42:33Z

redirect to N900 Hardware Accelerometer

← Older revision		Revision as of 13:42, 14 June 2010
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	~~[[Open development/Maemo roadmap/Fremantle\|Fremantle]] provides an accelerometer API. There are currently [https://bugs.maemo.org/show_bug.cgi?id=4724 two interfaces available]:~~		#REDIRECT [[N900 Hardware Accelerometer]]
	# ~~D-Bus~~
	~~# sysfs~~

	~~See also the~~ [~~http://talk.maemo.org/showthread.php?p=288990 related thread] at talk.maemo.org.~~

	~~== D-Bus ==~~

	~~Thomas Thurman (~~[http://twitter.com/marnanel marnanel]) has put together a simple demo of an application using accelerometers using the D-Bus interface. You can find sources and .deb up at http://people.collabora.co.uk/~tthurman/sandcastle/

	~~== sysfs ==~~

	~~Another way is to use the sysfs file information:~~

	~~/sys/class/i2c-adapter/i2c-3/3-001d/coord~~

	~~When reading that file you get 3 values X, Y and Z (provided on one line, separated by white space). Values are in mG (milli G). 1000 = 1 G~~

	~~{\| class="wikitable"~~
	\|-
	~~! Position~~
	~~! X~~
	~~! Y~~
	~~! Z~~
	\|-
	~~\| Lying on table (back down)~~
	~~\| 0~~
	~~\| 0~~
	~~\| -1000~~
	\|-
	~~\| Lying on table (face down)~~
	~~\| 0~~
	~~\| 0~~
	~~\| 1000~~
	\|-
	~~\| Sitting on table (bottom edge down)~~
	~~\| 0~~
	~~\| -1000~~
	~~\| 0~~
	\|-
	~~\| Sitting on table (right edge down)~~
	~~\| -1000~~
	~~\| 0~~
	~~\| 0~~
	\|-
	~~\| Sitting on table (left edge down)~~
	~~\| 1000~~
	~~\| 0~~
	~~\| 0~~
	\|-
	~~\| Bottom right corner down (approx.)~~
	~~\| -707~~
	~~\| -707~~
	~~\| 0~~
	\|}

	~~These are theoretical values. In real life your mileage will vary.~~

	~~An example can be found at: [http://git.zimmerle.org/?p=inclinometer.git;a=summary]~~

	~~== Using the data ==~~

	~~The ''X'' and ''Y'' values can be used to calculate<ref>Tom Pycke, ''[http://tom.pycke.be/mav/69/accelerometer-to-attitude~~ Accelerometer ~~to pitch and roll]''</ref> the pitch (that is, clockwise rotation) using the ''atan2'' function (note the inverted sign of ''y''):~~

	~~angle_in_radians = '''atan2'''(''x'', -''y'')~~

	~~Similar, ''Y'' and ''Z'' can be used to calculate the roll:~~

	~~angle_in_radians = '''atan2'''(''y'', -''z'')~~

	~~== Python ==~~

	~~Using the sysfs interface:~~
	~~<source lang="python">~~
	~~def get_rotation():~~
	~~f = open("/sys/class/i2c-adapter/i2c-3/3-001d/coord", 'r' )~~
	~~coords = [int(w) for w in f.readline().split()]~~
	~~f.close()~~
	~~return coords~~
	~~</source>~~

	~~And using the D-Bus interface:~~
	~~<source lang="python">~~
	~~import dbus~~
	~~bus = dbus.SystemBus()~~
	~~accel = bus.get_object('com.nokia.mce',~~
	~~'/com/nokia/mce/request',~~
	~~'com.nokia.mce.request')~~
	~~orientation , stand , face , x , y , z = accel.get_device_orientation()~~
	~~</source>~~
	x,y,z are the raw accelerometer measurements values, and the first three variables give text information about the device orientation. In particular, the first one informs about the landscape/portrait state.

	~~== Smoothed C interface ==~~

	~~This is a C function which returns smooth values from the accelerometer.~~
	~~Designed for applications running at >=25fps (otherwise it lags)~~

	~~(GPL code extracted from libliqbase: liqaccel.c)~~

	~~<source lang="c">~~
	~~static int ocnt=0;~~
	~~static int oax=0;~~
	~~static int oay=0;~~
	~~static int oaz=0;~~

	~~static const char *accel_filename = "/sys/class/i2c-adapter/i2c-3/3-001d/coord";~~

	~~int liqaccel_read(int ax,int ay,int *az)~~
	{
	~~FILE *fd;~~
	~~int rs;~~
	~~fd = fopen(accel_filename, "r");~~
	~~if(fd==NULL){ liqapp_log("liqaccel, cannot open for reading"); return -1;}~~
	~~rs=fscanf((FILE*) fd,"%i %i %i",ax,ay,az);~~
	~~fclose(fd);~~
	~~if(rs != 3){ liqapp_log("liqaccel, cannot read information"); return -2;}~~
	~~int bx=*ax;~~
	~~int by=*ay;~~
	~~int bz=*az;~~
	~~if(ocnt>0)~~
	{
	ax=oax+(bx-oax)0.1;
	ay=oay+(by-oay)0.1;
	az=oaz+(bz-oaz)0.1;
	}
	~~oax=*ax;~~
	~~oay=*ay;~~
	~~oaz=*az;~~
	~~ocnt++;~~
	~~return 0;~~
	}
	~~</source>~~

	~~[[Category:Development]]~~
	~~[[Category:Fremantle]]~~
	~~[[Category:Hardware]]~~
	~~[[Category:Sensors~~]]

imported_>amigadave: use

2010-06-14T13:33:50Z

use <source>

← Older revision		Revision as of 13:33, 14 June 2010
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	Using the sysfs interface:		Using the sysfs interface:
	<~~pre~~>		<source lang="python">
	def get_rotation():		def get_rotation():
	f = open("/sys/class/i2c-adapter/i2c-3/3-001d/coord", 'r' )		f = open("/sys/class/i2c-adapter/i2c-3/3-001d/coord", 'r' )
Line 78:		Line 78:
	f.close()		f.close()
	return coords		return coords
	</~~pre~~>		</source>

	And using the D-Bus interface		And using the D-Bus interface:
	<~~pre~~>		<source lang="python">
	import dbus		import dbus
	bus = dbus.SystemBus()		bus = dbus.SystemBus()
Line 88:		Line 88:
	'com.nokia.mce.request')		'com.nokia.mce.request')
	orientation , stand , face , x , y , z = accel.get_device_orientation()		orientation , stand , face , x , y , z = accel.get_device_orientation()
	</~~pre~~>		</source>
	x,y,z are the raw accelerometer measurements values, and the first three variables give text information about the device orientation. In particular, the first one informs about the landscape/portrait state.		x,y,z are the raw accelerometer measurements values, and the first three variables give text information about the device orientation. In particular, the first one informs about the landscape/portrait state.

Line 98:		Line 98:
	(GPL code extracted from libliqbase: liqaccel.c)		(GPL code extracted from libliqbase: liqaccel.c)

	<~~pre~~>		<source lang="c">

	static int ocnt=0;		static int ocnt=0;
	static int oax=0;		static int oax=0;
Line 131:		Line 130:
	return 0;		return 0;
	}		}
	</~~pre~~>		</source>

	[[Category:Development]]		[[Category:Development]]

imported_>javiplx: /* Python & D-Bus */

2010-04-20T09:36:14Z

Python & D-Bus

← Older revision		Revision as of 09:36, 20 April 2010
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	</pre>		</pre>

			And using the D-Bus interface
			<pre>
			import dbus
			bus = dbus.SystemBus()
			accel = bus.get_object('com.nokia.mce',
			'/com/nokia/mce/request',
			'com.nokia.mce.request')
			orientation , stand , face , x , y , z = accel.get_device_orientation()
			</pre>
			x,y,z are the raw accelerometer measurements values, and the first three variables give text information about the device orientation. In particular, the first one informs about the landscape/portrait state.

	== Smoothed C interface ==		== Smoothed C interface ==

imported_>onion: Categories

2010-03-26T08:14:10Z

imported_>milo: /* Using the data */

2010-02-23T17:47:54Z

Using the data

← Older revision		Revision as of 17:47, 23 February 2010
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	== Using the data ==		== Using the data ==

	The ''X'' and ''Y'' values can be used to calculate<ref>Tom Pycke, ''[http://tom.pycke.be/mav/69/accelerometer-to-attitude Accelerometer to pitch and roll]''</ref> the ~~roll~~ (that is, clockwise rotation) using the ''atan2'' function (note the inverted sign of ''y''):		The ''X'' and ''Y'' values can be used to calculate<ref>Tom Pycke, ''[http://tom.pycke.be/mav/69/accelerometer-to-attitude Accelerometer to pitch and roll]''</ref> the pitch (that is, clockwise rotation) using the ''atan2'' function (note the inverted sign of ''y''):

	angle_in_radians = '''atan2'''(''x'', -''y'')		angle_in_radians = '''atan2'''(''x'', -''y'')

	Similar, ''Y'' and ''Z'' can be used to calculate the ~~pitch~~:		Similar, ''Y'' and ''Z'' can be used to calculate the roll:

	angle_in_radians = '''atan2'''(''y'', -''z'')		angle_in_radians = '''atan2'''(''y'', -''z'')

109.108.3.85: /* sysfs */

2010-02-21T13:55:48Z

sysfs

← Older revision		Revision as of 13:55, 21 February 2010
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	\|-		\|-
	\| Bottom right corner down (approx.)		\| Bottom right corner down (approx.)
	\| -~~500~~		\| -707
	\| -~~500~~		\| -707
	\| 0		\| 0
	\|}		\|}

imported_>amigadave: wikify

2010-02-19T09:26:05Z

wikify

← Older revision		Revision as of 09:26, 19 February 2010
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	[[Fremantle]] provides an accelerometer API. ~~Currently<ref>~~[https://bugs.maemo.org/show_bug.cgi?id=4724 ~~#4724] ''Lack of official documentation on how to use the accelerometer''</ref> there are~~ two interfaces available:		[[Open development/Maemo roadmap/Fremantle\|Fremantle]] provides an accelerometer API. There are currently [https://bugs.maemo.org/show_bug.cgi?id=4724 two interfaces available]:
	# D-Bus		# D-Bus
	# sysfs		# sysfs
Line 123:		Line 123:
	</pre>		</pre>

	~~== References ==~~		[[Category:Development]]
			[[Category:Fremantle]]
	~~<small>~~
	~~<references/>~~
	~~</small>~~

	[[Category:Development]][[Category:Fremantle]]

imported_>amigadave: add [[Fremantle[[ link

2010-01-28T16:38:46Z

add [[Fremantle[[ link

← Older revision		Revision as of 16:38, 28 January 2010
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	Fremantle provides an accelerometer API. Currently<ref>[https://bugs.maemo.org/show_bug.cgi?id=4724 #4724] ''Lack of official documentation on how to use the accelerometer''</ref> there are two interfaces available:		[[Fremantle]] provides an accelerometer API. Currently<ref>[https://bugs.maemo.org/show_bug.cgi?id=4724 #4724] ''Lack of official documentation on how to use the accelerometer''</ref> there are two interfaces available:
	# D-Bus		# D-Bus
	# sysfs		# sysfs

189.115.169.82: /* sysfs */

2010-01-18T13:04:56Z

sysfs

← Older revision		Revision as of 13:04, 18 January 2010
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	These are theoretical values. In real life your mileage will vary.		These are theoretical values. In real life your mileage will vary.

			An example can be found at: [http://git.zimmerle.org/?p=inclinometer.git;a=summary]

	== Using the data ==		== Using the data ==

← Older revision		Revision as of 08:14, 26 March 2010
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	[[Category:Development]]		[[Category:Development]]
	[[Category:Fremantle]]		[[Category:Fremantle]]
			[[Category:Hardware]]
			[[Category:Sensors]]