[PD] joysticks with hid

[David Merrill]

Hello again hans & everyone -

I have a little more detail, after some investigation. I found an 
article that describes what I think is responsible for the spurious 
button presses, at:

http://www.linux-magazine.com/issue/04/LinuxUSB.pdf

So it seems that the sidewinder *does* send out buttonpresses when the 
continuous DOF gets near any edge of its range. But when I look at the 
output of evtest, I can see that the button codes for the near-edge 
condition are actually different than the codes for the thumb buttons - 
but I think the [hid] object is mapping the different codes to the same 
output, causing the confusing condition that I noticed:

vertical edge condition: evtest says: 259 (Btn3), [hid] is mapping this 
to the same output as 291 (TopBtn), sending "key btn_3 1" for both.
horizontal:  evtest says: 258 (Btn2), [hid] is mapping this to the same 
output as 290 (ThumbBtn2), sending "key btn_2 1" for both.

So is there a way to ask [hid] to not conflate codes 259/291, and 
258/290? Or to have [hid] just spit out raw codes, rather than the 
processed textual output that I'm seeing?

thanks!
-David M.

David Merrill wrote:

> Hello Hans, et al -
>
> I've got another puzzling joystick bug that's showing up today as i 
> play around with the [hid] object in linux (Ubuntu Hoary, kernel 
> 2.6.10-5-686).
>
> I am using a Microsoft "Sidewinder Dual Strike" USB joystick, and 
> after changing the permissions on /dev/input/event*
> I can successfully peek at the output with evtest, and I can open the 
> device for reading with the [hid] object.
>
> The strange behavior is that when I push the continuous 
> input-degree-of-freedom near one edge or another, a *button-press* 
> registers, but I have not pressed any button (I see this buttonpress 
> in both evtest, and hans' [hid] external). The continuous DOF of this 
> joystick has a springy region near the edges where there is some 
> resistance - and I get the spurious buttonpress when I cross into this 
> region.
>
> I tried the same joystick in windows, and I don't get the spurious 
> buttonpresses. (I tested it with both the windows control panel "game 
> controllers" interface, and jsarlo's joystick external).
>
> Has anyone see this kind of behavior? Any ideas why it doesn't show up 
> in Windows, but does in Linux? I'd be really interested to find out 
> how to fix something like this..
>
> thanks,
> -David Merrill
>
> Hans-Christoph Steiner wrote:
>
>>
>> On Apr 8, 2005, at 12:11 PM, august wrote:
>>
>>>>> hmm.  I have the 'evdev' module loaded, but there is nothing at
>>>>> /dev/input/event*
>>>>
>>>>
>>>>
>>>> You need:
>>>>
>>>> mknod /dev/input/event0 c 13 64
>>>> mknod /dev/input/event1 c 13 65
>>>> mknod /dev/input/event2 c 13 66
>>>> mknod /dev/input/event3 c 13 67
>>>> mknod /dev/input/event4 c 13 68
>>>> mknod /dev/input/event5 c 13 69
>>>> ...
>>>
>>>
>>>
>>>
>>> thanks....I had the devices listed alright....but the permissions  
>>> weren't
>>> set.  maybe someone else is having the same problem.
>>>
>>> doing "chmod +r /dev/input/event*"  should do the trick.
>>>
>>> now, HID works as expected.....but I only get a resolution from 
>>> 0-255  on
>>> the joystick axis.  Is that how it is supposed to be?   I thought the
>>> resolution was much higher.
>>>
>>> best -august.
>>>
>>> _______________________________________________
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>>
>> "Supposed to" might be the key word there.  That value, AFAIK, 
>> depends  on the hardware.  I have two joysticks: a Logitech Wingman, 
>> which  outputs 0-127, and  a Saitek Force 3D, which outputs 0-4091.  
>> This is  also why I wrote the [autoscale] object which is used in 
>> the  [joystick], [tablet], and [mouse] objects.  These objects always 
>> output  between 0 and 1, converting the output range of the device, 
>> to  resolution between 0 and 1.  Then when you write a patch for one  
>> joystick, it'll stick work with other joysticks.
>>
>> .hc
>>
>> ________________________________________________________________________ 
>> ____
>>
>>            "The arc of history bends towards justice."
>>                                                               Dr.  
>> Martin Luther King, Jr.
>>
>>
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>
>
>
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