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Author Topic: Logitech G25 and APAC  (Read 4788 times)

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jonbenderr

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Logitech G25 and APAC
« on: October 30, 2018, 06:55:16 am »
So I've been working on this driving cab off and on for a bit and am ready to really start digging in.

Right now, the plan is to use the steering wheel and shifter from a logitech g25 system and use an A-Pac to connect the original arcade accelerator and brake to the PC.

Using the original arcade hardware for the brake and accelerator will just look a lot nicer.  I've seen the inverted pedals setup for the logitech, just not a huge fan of that.  Plus, I don't have any plans at all for setting up games that need a clutch so that pedal would just sort of be hanging there useless which bugs me more than it probably should.

My question is am I setting myself up for huge headaches in regards to configuring games?

Will the logitech system even work without the pedals connected?

shaolindrunkard

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Re: Logitech G25 and APAC
« Reply #1 on: October 30, 2018, 01:18:33 pm »
There's probably no need to use an APAC. In fact it will probably screw things up more than you want. Both the pedals from the original cab and the pedals from the g25 use potentiometers. All you have to do is find a pinout for the G25 pedals and wire the Arcade pedals in the same way. If the Potentiometer value is not the same for both sets of pedals you can change out the Pots on the arcade pedals to match what the g25 uses.

The easiest way would probably be to open up the G25 pedals, and then take a picture of the wiring or at least write down which wires go where. Then desolder or disconnect the original cable from and the G25 pedals and reconnect it to the arcade pedals in the same way.

May take some fiddling ad you may have to swap some wires if they wind up working backwards but its not super hard to do.

PL1

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Re: Logitech G25 and APAC
« Reply #2 on: October 30, 2018, 10:08:37 pm »
If the Potentiometer value is not the same for both sets of pedals you can change out the Pots on the arcade pedals to match what the g25 uses.
To clarify and expand on this:

If it's a 3-wire per pot setup, you shouldn't need to swap the different-value pedal pot since it's working as a voltage divider.
- The encoder is measuring the voltage so a different-value pot is usually OK.

If it's a 2-wire per pot setup, you probably need to swap the different-value pedal pot since it's working as a variable resistor.
- The encoder is measuring the resistance so a different-value pot is usually not OK.


Scott

shaolindrunkard

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Re: Logitech G25 and APAC
« Reply #3 on: October 30, 2018, 10:32:54 pm »
If the Potentiometer value is not the same for both sets of pedals you can change out the Pots on the arcade pedals to match what the g25 uses.
To clarify and expand on this:

If it's a 3-wire per pot setup, you shouldn't need to swap the different-value pedal pot since it's working as a voltage divider.
- The encoder is measuring the voltage so a different-value pot is usually OK.

If it's a 2-wire per pot setup, you probably need to swap the different-value pedal pot since it's working as a variable resistor.
- The encoder is measuring the resistance so a different-value pot is usually not OK.


Scott

Indeed.

jonbenderr

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Re: Logitech G25 and APAC
« Reply #4 on: October 31, 2018, 05:27:11 am »
Thanks guys!

That's actually a brilliant solution!

I know the arcade hardware uses 3 wire pots.  Not sure about the G25 but I will pop it open and have a look!

EDIT:  Was just looking at g25 disassembly videos.  3 wire pots for the g25 as well.

Should be fairly straight forward!  Thanks again guys!
« Last Edit: October 31, 2018, 05:41:39 am by jonbenderr »

baritonomarchetto

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Re: Logitech G25 and APAC
« Reply #5 on: November 01, 2018, 05:39:41 am »
Having 3 wires connected doesn't necessarily mean that another pot value will work. Often in controllers pots are wired in parallel and different values could lead to problems on some axis. Decent potentiometers are sold for nuts nowadays, in case your pot replacement doesn't work... ;)

PL1

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Re: Logitech G25 and APAC
« Reply #6 on: November 01, 2018, 07:07:13 am »
If you're referring to gas and brake pedals wired in series as a single axis, then both pedals do need to be the same value.





Are you referring to the Dreamcast MadCatz MC2 controller pots wired in parallel? (pot value shouldn't cause a problem AFAIK)



If that's not what you're referring to, I'm not sure what you mean about problems with pots being wired in parallel.   :dizzy:

You've done more of these controller hacks than I have.

Do you have a particular controller or schematic as an example where you ran into problems?   :dunno


Scott

baritonomarchetto

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Re: Logitech G25 and APAC
« Reply #7 on: November 01, 2018, 09:29:38 am »
If I remember well, xbox 360 pads have those sticks with two orthogonal pots, one for each axis, wired in parallel. If you change one of the two axis pot (100 K ohm) with a different value pot, it will not work correctly.

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Re: Logitech G25 and APAC
« Reply #8 on: November 01, 2018, 12:57:14 pm »
If I remember well, xbox 360 pads have those sticks with two orthogonal pots, one for each axis, wired in parallel. If you change one of the two axis pot (100 K ohm) with a different value pot, it will not work correctly.
Pretty sure that XBox 360 used 10k pot thumbsticks.

Maybe what you're describing relates to some of the older controllers that didn't have a "Common Ground" setup, but I haven't found anything that confirms it.   :dunno

BadMouth tried other value pots for a newer XBox 360 padhack w. twin analog joysticks.

This post mentions having more jitter problems with 5k pots than 10k or 50k.

Ohm's Law shows that using different value pots would cause a difference in the amount of current flow for a given voltage.

Voltage (V) = Current (Amps) * Resistance (Ohms)
    5v = 1mA * 5k Ohm
    5v = 0.5mA * 10k Ohm

Even if you wired a 5k and a 10k potentiometer in parallel, both would still act as voltage dividers.

The 5k pot would draw twice the current as the 10k, but the A/D circuit in the encoder would still be measuring the wiper voltage.

If it was measuring resistance or current flow, the 5k and 50k pots wouldn't have worked in BadMouth's tests.


Scott

shaolindrunkard

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Re: Logitech G25 and APAC
« Reply #9 on: November 01, 2018, 01:25:11 pm »
Yeah I can confirm, in my setup I have a 5k pot wired to the analog stick(s) on an 360 controller and 10k pots wired to the triggers. Works fine. Slight jitter with the 5k but it doesn't adversely effect anything.

jonbenderr

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Re: Logitech G25 and APAC
« Reply #10 on: November 02, 2018, 08:15:04 am »
Just an update...

Wiring the original gas/brake pots into the g25 system works beautifully!!! 

Thanks again for the tip guys.


shaolindrunkard

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Re: Logitech G25 and APAC
« Reply #11 on: November 02, 2018, 10:36:36 am »
Just an update...

Wiring the original gas/brake pots into the g25 system works beautifully!!! 

Thanks again for the tip guys.

Nice!