[Gta04-owner] Second trial with QtMoko2

Thu Apr 12 14:51:48 CEST 2018

> Am 12.04.2018 um 14:32 schrieb Sven Dyroff <S.Dyroff at phytec.de>:
> 
> Hello Nikolaus, 
> 
> it would astonish me if you're right, but of course I'll then test it again in order to give you a chance to astonish me...    :-)) 

I have done this test for you:

GTA04A4 and GTA04A5 with display upside on the table with the same µSD card (i.e. boot A5 first, then swap card and boot A4).
Run evtest /dev/input/accel | head -20 and write down highest X/Y/Z values.

On a GTA04A5:

root at letux:~# evtest /dev/input/accel | head -20
Input driver version is 1.0.1
Input device ID: bus 0x0 vendor 0x0 product 0x0 version 0x0
Input device name: "accelerometer-iio-input-bridge"
Supported events:
  Event type 0 (EV_SYN)
  Event type 3 (EV_ABS)
    Event code 0 (ABS_X)
      Value     14
      Min     -511
      Max      511
    Event code 1 (ABS_Y)
      Value    -32
      Min     -511
      Max      511
    Event code 2 (ABS_Z)
      Value   -253
      Min     -511
      Max      511
Properties:
Testing ... (interrupt to exit)
root at letux:~# 

This means: X=14/256 = +5%, Y=--32/256 = -12%, Z=-253/256 = -99%

On a GTA04A4:

root at letux:~# evtest /dev/input/accel | head -20
Input driver version is 1.0.1
Input device ID: bus 0x0 vendor 0x0 product 0x0 version 0x0
Input device name: "accelerometer-iio-input-bridge"
Supported events:
  Event type 0 (EV_SYN)
  Event type 3 (EV_ABS)
    Event code 0 (ABS_X)
      Value    -15
      Min     -511
      Max      511
    Event code 1 (ABS_Y)
      Value     -5
      Min     -511
      Max      511
    Event code 2 (ABS_Z)
      Value    274
      Min     -511
      Max      511
Properties:
Testing ... (interrupt to exit)
root at letux:~# 

This means: X=-15/256 = +6%, Y=--5/256 = -2%, Z=274/256 = +107%

Comparing A4 and A5: they basically behave *the same* regarding the range
and report both +/-256 for 1g. They just differ in the orientation of the sensor.

I.e. the Z axis also has a sign error. This is still missing in my correction patch.
To make it really precise I should rotate both devices by 90° and write down all
values...

What I don't know and can't compare is if they behave like a GTA02... And
if a total value of ~1g is what QtMaze expects. And if the QtMaze makes use
of the Z-axis at all (doesn't look as if it does).

BR,
Nikolaus

> 
> Best regards 
>    Sven 
>     
> 
> 
> 
> 
> Von:        "H. Nikolaus Schaller" <hns at goldelico.com> 
> An:        List for communicating with real GTA04 owners <gta04-owner at goldelico.com> 
> Datum:        12.04.2018 14:25 
> Betreff:        Re: [Gta04-owner] Second trial with QtMoko2 
> Gesendet von:        "Gta04-owner" <gta04-owner-bounces at goldelico.com> 
> 
> 
> 
> Hi Sven, 
> 
> Am 12.04.2018 um 14:19 schrieb Sven Dyroff <S.Dyroff at phytec.de <mailto:S.Dyroff at phytec.de>>: 
> 
> Hello Nikolaus, 
> 
> fine, but this will "only" correct the swapping. It will still not correct the calibration. 
> 
> Whereat the comments of the affected source give a nice hint: "On my GTA04, sitting flat on the table, the raw Z acceleration value is about 256, so we divide by 256 here." 
> 
> So I suggest to add a further printf of the value of "accel -> z", in order that your code will provide you the needed calibration data that you can then use for "accel -> [xyz]scale" in case of having detected a GTA04A5. 
> 
> It is easier than a printf: evtest /dev/input/accel reports the range [0..512] and the current values. 
> 
> I have checked that and the GTA04A5 also reports roughly 256. 
> 
> So I think you should test (after I have uploaded it to the server) if it is now ok for you. 
> 
> BR, 
> Nikolaus 
> 
> 
> Best regards 
>   Sven 
>    
> 
> 
> 
> 
> Von:        "H. Nikolaus Schaller" <hns at goldelico.com <mailto:hns at goldelico.com>> 
> An:        Sven Dyroff <S.Dyroff at phytec.de <mailto:S.Dyroff at phytec.de>> 
> Kopie:        List for communicating with real GTA04 owners <gta04-owner at goldelico.com <mailto:gta04-owner at goldelico.com>> 
> Datum:        11.04.2018 19:21 
> Betreff:        Re: [Gta04-owner] Second trial with QtMoko2 
> 
> 
> Hi Sven, 
> 
> Am 05.04.2018 um 18:05 schrieb Sven Dyroff <S.Dyroff at phytec.de <mailto:S.Dyroff at phytec.de>>: 
> 
> Hello Nikolaus, 
> 
> > I have now booted my GTA04A4 and the orientation is completely correct. 
> > Hm. Maybe a subtle difference between GTA04A4 and A5? They use different accelerometer chips. 
> 
> something like that is what I already assumed. Would have wondered me if some scaling factors would have gone lost by just rebuilding QtMoko... 
> 
> I have now added a device version detection to swap the horizontal axis if we run on a GTA04A5: 
> 
> http://git.goldelico.com/?p=gta04-qtmoko.git;a=commit;h=04c30a3b18be8b55148427d6c63423837f6a77cc <http://git.goldelico.com/?p=gta04-qtmoko.git;a=commit;h=04c30a3b18be8b55148427d6c63423837f6a77cc> 
> 
> I have not yet published the new debian packages, but will do soon. So apt-get update will not 
> yet find anything new. 
> 
> BR, 
> Nikolaus 
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