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Accelerometer on a laptop?!? What? Where?
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Matte88
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PostPosted: Mon Jan 14, 2013 5:19 pm    Post subject: Accelerometer on a laptop?!? What? Where? Reply with quote

Mine is a Lenovo Essential laptop (not a tablet or convertible, a simple laptop) and today I found this
Code:
I: Bus=0019 Vendor=0000 Product=0000 Version=0000
N: Name="Acer BMA150 accelerometer"
P: Phys=wmi/input1
S: Sysfs=/devices/virtual/input/input8
U: Uniq=
H: Handlers=event8 js0
B: PROP=0
B: EV=9
B: ABS=7

Can anyone help me please find out this device?
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eccerr0r
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PostPosted: Mon Jan 14, 2013 5:28 pm    Post subject: Reply with quote

They're not completely unheard of....

Apparently you got yours configured as a joystick (/dev/input/js0). You can try getting some applications that use the joystick to see what it does...
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gerard82
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PostPosted: Mon Jan 14, 2013 8:31 pm    Post subject: Reply with quote

Accelerometers in laptops are there to protect the hard drive in case it's dropped I think.
But I don't own one so I am not sure.
It can be found in the kernel config under "Device Drivers > Miscellaneous devices".
How to make use of it I have no idea.
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eccerr0r
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PostPosted: Mon Jan 14, 2013 9:52 pm    Post subject: Reply with quote

I think mine also has some usage in determining when to turn the fan on. In multiple situations when I tip my laptop a bit, the fan will come on full speed - I suppose the firmware is assuming that if it needs power it will reduce processing speed to prevent overheating but it still has a lot of heat backed up. However if it senses the laptop being tipped, it's likely got an opening where the vents are free and it should pump out as much heat as it can (turning on fans full blast) before it gets blocked on a lap or soft material once more...

That's what I suspect at least.

But yes, hdd protection is another good use for it. It unfortunately isn't very useful in my laptop now (SSD's don't need to be parked...)
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Matte88
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PostPosted: Tue Jan 15, 2013 1:44 am    Post subject: Reply with quote

Tipping my laptop and nothing happened... I can't understand to which device/hw-part/button is related the accelerometer.
The docs about my model doesn't talk about HDD protection (is an entry-level laptop), so this input device remains unknown... ?... 8O

[EDIT]
Strange behaviour... Look at this
Code:
laptoo ~ # cat /dev/input/mouse0
▒�▒�▒�(�8��8��8��8��8��8��8��8��▒�▒�(�▒�▒(�(�(�(��▒�▒�^C
laptoo ~ # cat /dev/input/mouse1
c^C
laptoo ~ # cat /dev/input/js0
cat: /dev/input/js0: Operazione non permessa
With mouse0 you can see input, mouse1 shows no activity and js0 gives Operation not permitted...
Code:
I: Bus=0003 Vendor=046d Product=c05a Version=0111
N: Name="Logitech USB Optical Mouse"
P: Phys=usb-0000:00:1a.0-1.3/input0
S: Sysfs=/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3:1.0/input/input6
U: Uniq=
H: Handlers=mouse0 event6
B: PROP=0
B: EV=17
B: KEY=ff0000 0 0 0 0
B: REL=143
B: MSC=10

I: Bus=0019 Vendor=0000 Product=0000 Version=0000
N: Name="Acer BMA150 accelerometer"
P: Phys=wmi/input1
S: Sysfs=/devices/virtual/input/input9
U: Uniq=
H: Handlers=event9 js0
B: PROP=0
B: EV=9
B: ABS=7

I: Bus=0011 Vendor=0002 Product=000e Version=0000
N: Name="ETPS/2 Elantech Touchpad"
P: Phys=isa0060/serio1/input0
S: Sysfs=/devices/platform/i8042/serio1/input/input10
U: Uniq=
H: Handlers=mouse1 event10
B: PROP=1
B: EV=b
B: KEY=6420 30000 0 0 0 0
B: ABS=260800011000003
Code:
crw-r--r--  1 root root 13,  0 15 gen 02.46 js0
crw-r-----  1 root root 13, 32 15 gen 02.46 mouse0
crw-r-----  1 root root 13, 33 15 gen 02.46 mouse1
[/EDIT]
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_______0
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PostPosted: Tue Jan 15, 2013 2:11 am    Post subject: Reply with quote

1
Code:
jstest <device>

2 give it a lappy dance

3
Code:
<crazy numbers>

4 FUN!!

thinkpads are known to use gyros for their hdds.

http://www.thinkwiki.org/wiki/HDAPS

thread solved.
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Matte88
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PostPosted: Tue Jan 15, 2013 2:38 pm    Post subject: Reply with quote

_______0 wrote:
1
Code:
jstest <device>

2 give it a lappy dance

3
Code:
<crazy numbers>

4 FUN!!

thinkpads are known to use gyros for their hdds.

http://www.thinkwiki.org/wiki/HDAPS

thread solved.
Code:
$ jstest /dev/input/js0
jstest: Operation not permitted
Code:
$ su -c 'jstest /dev/input/js0'
Password:
jstest: Operation not permitted
8O
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ppurka
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PostPosted: Tue Jan 15, 2013 2:53 pm    Post subject: Reply with quote

Don't know about your laptop, but for thinkpads there used to be a program called hdapsd, along with a corresponding module(?) in tp-smapi. One would run it as a daemon - it would read the accelerometer data and it would park the hard drive head whenever there was a sudden motion of the laptop. Before my thinkpad broke down, I used hdaps and it used to work.
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PostPosted: Sun Feb 03, 2013 10:20 am    Post subject: Travelmate? Reply with quote

I just found the same device on my Acer TravelMate 5742. For ThinkPads I wouldn't be so surprised, but this is a rather lower-end machine. It seems strange, I've found no reference about accelerometers in this line of machines, neither in the acer_wmi.c file.
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