[Gta04-owner] Making sense of the sensors.

Belisko Marek marek.belisko at gmail.com
Thu Aug 9 23:23:27 CEST 2012


On Thu, Aug 9, 2012 at 11:13 PM, Benjamin Deering
<ben_deering at swissmail.org> wrote:
>
> It is going crazy.  I watched the 3 axis in sensmon.  X and Y are reasonable
> if I adjust the range, but Z sends random looking garbage.  Even moving a
> powerful magnet close around the phone makes no noticeable change.
Maybe there is some bug in driver. I've remember when working on
driver I've got -4096 for Z value
most of the time which means invalid but cannot figure out why.
Anybody else can share test results?
>
>
> On 08/09/2012 05:07 PM, Michele Brocco wrote:
>>
>> Is the needle going crazy or is it constantly showing in the same
>> direction if you don't move your device?
>>
>>
>> On 8/9/12, Benjamin Deering<ben_deering at swissmail.org>  wrote:
>>>
>>> I played a bit with valacompass on GTA04.  Libsensmon would need a
>>> BMA150 module for tilt compensation to work, but I commented out the
>>> accelerometer code in my build.
>>>
>>> The hmc5843 driver for the latest SHR kernel has the sysfs files in a
>>> different place.
>>>
>>> I changed .Sensmon/config to include:
>>> [Hmc5843Source]
>>> device=/sys/bus/i2c/devices/2-001e/iio:device0
>>>
>>> The sysfs file 'rate' seems to have changed to sampling_frequency.
>>>
>>> X,Y,and Z values come from separate files.  I'm not a vala programmer,
>>> but I can send what I did to get them.
>>>
>>> I had to adjust in_magn_range to get the Y axis to show anything but
>>> -4096.0
>>>
>>> I don't know how important the tilt compensation is, but with all my
>>> changes the needle in valacompass does not point north.  The direction
>>> it points seems to change when I rotate the phone, but it is very
>>> noisy.  I think there is some interference from the speaker magnets as I
>>> was able to get a reading on the Y axis without adjusting the range if I
>>> brought a magnet near the phone.  I have Slyon's 3d printed speaker box
>>> and 2 speakers, maybe those with a single speaker will have different
>>> results.
>>>
>>> Ben
>>>
>>> On 08/04/2012 02:10 PM, Michele Brocco wrote:
>>>>
>>>> On 8/4/12, NeilBrown<neilb at suse.de>   wrote:
>>>>>
>>>>> The compass seems to have a strong bias on all axes. Presumably some
>>>>> magnet
>>>>> in the GTA04 (speaker?) needs to be compensated for.  Has anyone played
>>>>> with
>>>>> this at all?  Figured out how to calibrate, then how to convert the 3
>>>>> numbers
>>>>> into  a compass direction?
>>>>
>>>> hi neil,
>>>>
>>>> I wrote a proof of concept user space compass application for the
>>>> navigation board (http://wiki.openmoko.org/wiki/ValaCompass). you can
>>>> take a look at the source code if you want. i wanted to update the
>>>> application once the kernel in shr will support this sensor and the
>>>> accelerometers. but currently I am very busy and could not chek if
>>>> everything is there already.
>>>>
>>>> regards,
>>>>
>>>> Michele
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>
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cheers,

mbe

-- 
as simple and primitive as possible
-------------------------------------------------
Marek Belisko - OPEN-NANDRA
Freelance Developer

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