Re: [Enigma-devel] TiltStick, USB based tilt sensor

[Till Harbaum / Lists]

Hi,

i was fiddling around with that some time ago and it didn't work.
But the first tiltsticks at that time were pretty unprecise. This has
changed and using jscal is now eliminating the death zone.

There's still a problem left: The sensivity of the tiltstick ranges from
-2G to +2G, but by tilting you can only reach +/- 1G (at least on
this planet). So using jscal will result in the max/min range mapping
being limited to +/- 1G where the device itself can do +/-2G.

Anyway, thanks for pointing me to jscal again.

But there's still one reason left to use the event interface: I am doing
this to use it on the Nokia internet tablets. These unfortunately don't
include any joystick routines in the kernel at all. So my only way to
to get the TiltStick to work there is with the event interface.

Till

Am Dienstag 05 Februar 2008 schrieb Tacvek:
> ----- Original Message -----
> From: "Till Harbaum / Lists" <address@hidden>
> To: <address@hidden>
> Sent: Sunday, February 03, 2008 2:27 PM
> Subject: Re: [Enigma-devel] TiltStick, USB based tilt sensor
>
> > Hi,
> >
> > hmm, no feedback. Please let me explain why i am bothering you with this.
> > The sdl layer supports joysticks and the tiltstick is a joystick. Thus
> > everything should be a no brainer.
> >
> > Unfortunately there's some magic in the linux joystick driver (i never
> > checked
> > if windows does the same) that extends the "death zone" of any joystick
> > somewhat. This means that the range around zero of each axis is extended
> > a little bit to make sure that a slightly miss-calibrated joystick
> > doesn't permanently report tiny movements. Thus the joystick has to moved
> > a significant amount before starting to report values != 0.
>
> I would expect the nullzone to be fully user configurable. Having magic
> hardcoded into the kernel that cannot be turned off at runtime does not
> sound like standard procedure to me. Are you sure you cannot specify the
> null zone in the kernel level joystick calabration tool? (jscal, part of
> the joystick package).
> Since you seem to have hardware level calibration, in theory the software
> calibration could be set to just output the raw input values, with no
> nullzone.
> Is that not correct?
> I'm pretty sure that can be done, but I'm having trouble seeing how this is
> done by just reading the driver source.