JW24A8-8-S problem: Jitter?

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anegroo
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Joined: Thu Jan 17, 2013 1:36 pm

JW24A8-8-S problem: Jitter?

Post by anegroo »

Hello,
I would like to use a JW24A8-8-S as a custom gamecontroller in vvvv. I have made the electric connections between board and buttons and potentiometers, and it is recognized by Windows XP and the vvvv program too. The buttons all are working fine, but there is a problem with the potmeters. I can change the value of all three axes from -1 to 1. But if the values differs from this min-max values the output is not stable. They are varying a little bit, almost continuously (here is a little video about this). It is a jitter problem? How could I avoid it?

I opened a thread in the vvvv forum (here), but nobody helped me regarding to this problem. You can download from there also the patch I made in vvvv for this circuit. I don`t know what I am doing wrong. Can you help me with any suggestion please? I am not a programmer, I only have a little experience in electronics. Thanks.
Guido Körber
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Re: JW24A8-8-S problem: Jitter?

Post by Guido Körber »

-1 to 1 is not the native range of the JoyWarrior (0..255 is the actual output range). I assume there is some scaling taking place?

+/- one digit of jitter is always present in A/D conversion. Depending on the quality of the pots, length of the cables, and noise in the environment there can be a bit more noise.

Make sure that the cables between the JoyWarrior and the pots are as short as possible.

Are you using our JW24MOD-A8-x modules, or have you done your own PCB?
anegroo
Posts: 3
Joined: Thu Jan 17, 2013 1:36 pm

Re: JW24A8-8-S problem: Jitter?

Post by anegroo »

Hi Guido,
Thanks for the reply!

Yes, there is taking place some internal scaling to this range.
I bought the controller with your PCB. I only attached the USB cable, the buttons and potmeters. Now the potmeters are connected with aprox. 10cm long non-shielded cables. But I would like to use longer cables, I don`t know if it is possible... What kind of potmeters and cables you suggest? If the cables are shielded they could be longer? The three cables conected to one potmeter can be shielded together (common shield) or is better to be shielded each cable individually? The shield and possibly the potmeters metallic body have to be connected to the USB ground, I think....
Thanks
Guido Körber
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Re: JW24A8-8-S problem: Jitter?

Post by Guido Körber »

Shielding the cables can help, but try to keep them as short as possible, it is better to move the module to the pots. USB is quite immune to interference, but the signals to the pots are analog.
anegroo
Posts: 3
Joined: Thu Jan 17, 2013 1:36 pm

Re: JW24A8-8-S problem: Jitter?

Post by anegroo »

I found a solution in vvvv forums. There is noise reduction patch, a kind of filter, which can eliminate this jitter problem.
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