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Main => Main Forum => Topic started by: maffewl on November 13, 2012, 07:39:24 pm

Title: Invert Trackball Directions
Post by: maffewl on November 13, 2012, 07:39:24 pm
Looks like I accidentally installed the trackball upside down.  :banghead:

Instead of having to undo the mounting brackets and cutting a new hole for wiring, is there a way I can just invert the trackball directions in windows or mame?

 
Title: Re: Invert Trackball Directions
Post by: PL1 on November 13, 2012, 08:04:19 pm
Swapping the two data lines on each axis should do it IIRC.

X1<==>X2

Y1<==>Y2

Leave the 5v and ground wires as is.


Scott
Title: Re: Invert Trackball Directions
Post by: maffewl on November 13, 2012, 08:06:59 pm
Sorry, I should have mentioned that it is connected through PS2.  I guess my only option is to un-mount and start drilling.   :angry:

Thanks though PL1
Title: Re: Invert Trackball Directions
Post by: PL1 on November 13, 2012, 08:09:45 pm
It still uses opto boards, or does it have the encoder on the same PCB?


Scott
Title: Re: Invert Trackball Directions
Post by: maffewl on November 13, 2012, 11:37:20 pm
I'm really not sure what any of that means?  Sorry, I'm new to most of this stuff.
Title: Re: Invert Trackball Directions
Post by: PL1 on November 14, 2012, 12:27:48 am
The trackball works like a mechanical mouse (http://en.wikipedia.org/wiki/Mouse_%28computing%29#Mechanical_mice).

Further details and better pictures here (http://computer.howstuffworks.com/mouse2.htm) and there's an explanation of quadrature waveforms here (http://en.wikipedia.org/wiki/Optical_encoder#Incremental_rotary_encoder).

There are 4 wires per axis leading to the encoder:
1. 5v - operating voltage for the LED
2. Data A
3. Data B
4. Ground (Sometimes jumpered inside the trackball case, leaving one axis with only 3 wires)

By swapping Data A for Data B, you are swapping quadrature waveform A for waveform B which the encoder translates as turning the other way.

(https://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Quadrature_Diagram.svg/600px-Quadrature_Diagram.svg.png)


Scott
Title: Re: Invert Trackball Directions
Post by: BadMouth on November 14, 2012, 09:49:01 am
What he's saying is swapping two of the wires coming from the circuit board will reverse direction.

If you're not comfortable with that, you can invert the axis in MAME.
In the in game menu (TAB by default), go to analogue controls and there should be an option to invert axis.

There should be a line for it in the mame.ini file that will do it globally for all games, but I'm at work and don't have it to look at.

It will still be backwards for everything outside of MAME.
Title: Re: Invert Trackball Directions
Post by: maffewl on November 14, 2012, 02:24:16 pm
Thanks for the help everyone.  I decided it would be easier for me to just disassemble the control panel and drill a new hole on the other side of the trackball bracing.  I am wanting to update my artwork anyways, so this will give me a chance to do so.  Again, much thanks!