Fool analog controls with button

[jkl]

Hi there,
I recently modded a Dreamcast MadCatz MC2 Wheel for use with my Naomi setup.
Everything is working (I mean if the goal is automatic gearing, since I didn't wired any control for it).

But I wonder if I can have a feature that the wheel has with real Dreamcast, the "full state" of pedals on the buttons built into the wheel. Doing so the pedals are optionals, you can use just the wheel (in this case of course no analog control, you have no gas/full gas as well as no brake/full brake.

Question is: how could I fool the JVS board expecting to have three pins, gnd, vcc, and a variable signal pin (the central one in potentiometers)?

Many thanks in advance,
JKL

[Howard_Casto]

Sure... it isn't that hard.  Get a resistor the same value as the potentiometer and connect it between the button  and vcc and the other end of the button goes to ground.  At least I think... machines that use all three pins are a bit tricky, but it is possible.  Maybe someone else can chime in on this one. 

[PL1]

I wonder if I can have a feature that the wheel has with real Dreamcast, the "full state" of pedals on the buttons built into the wheel. Doing so the pedals are optionals, you can use just the wheel (in this case of course no analog control, you have no gas/full gas as well as no brake/full brake.

Question is: how could I fool the JVS board expecting to have three pins, gnd, vcc, and a variable signal pin (the central one in potentiometers)?

That sounds like your setup has gas and brake on a single axis like this:



The single axis setup translated into a schematic with the resulting voltages:
- Pink (brake) = Vcc
- Blue/Yellow = Wiper (center pin)
- Blue/Red = Ground



Connect the pushbuttons to these potentiometer leads:

- The brake button shorts Vcc to Wiper when presed.

- The gas button shorts Wiper to ground when pressed.

If the gas and brake functions are swapped (i.e. Vcc on wiper = gas pedal pressed), swap Vcc for ground.


Scott
Edit: Clarified the button connection points.

[Howard_Casto]

Glad you chimed in.  I didn't have a clue what he was asking, apparently. 

[jkl]

Many many thanks guys!!
PL1 was absolutely right.
I ripped off my wheel and added 2 momentary buttons behind the wheel, wiring them as PL1 said.
Work like a charm.
I added 2 buttons because I wanted to mantain all the functionality of original Dreamcast wheel, so the orange factory buttons are still working like madcatz did (they're doing it with an integrated circuit).

Many thanks again, you rock!

JKL

[PL1]

Glad to assist.   


Scott

[baritonomarchetto]

This is gold and should be cited/reported in the badmouth's driving racing info topic!

[SegaOutrun]

what tutorial did u use to wire the dreamcast wheel to the naomi? ive always wanted a netbooting naomi but, finding the arcade wheel and pedal for initial d wasnt cheap

[jkl]

It's all about the JVS interface you're using. Since what I know you could have a JVS2JAMMA, a JVS type 1, type 2, type 3. I'm almost sure the analog pinout is exactly the same on all these boards, since all of them have 26 pins analog connector, but I can't ensure it to you, do it at your risk.
I have a JVS2JAMMA, this one (http://triplemoonstar.brinkster.net/theshed/default.asp?stockid=1854).
On that site, if you search for other JVS boards, you find them with pinout in description (mine hadn't):
- type 1 http://triplemoonstar.brinkster.net/theshed/default.asp?stockid=1718
- type 2 http://triplemoonstar.brinkster.net/theshed/default.asp?stockid=2098
- type 3 http://triplemoonstar.brinkster.net/theshed/default.asp?stockid=2532

JVS2JAMMA has a jamma standard pinout on the jamma connector, the only button missing is button 6 for fighters, that's NOT on jamma connector but instead is the fourth from tha bottom on the white CN connector you have on left side of the board when jamma end is towards you. To enable it you have to move the jumper located top left of the board.

As for the analog inputs, they're on the only black connector (26 pin).
For pinout I simply followed the tables this guy did (http://www.gamoover.net/Forums/index.php?topic=32526.0).

For the wheel (steer, gas, brake) you only need 5 pins: 1 gnd (all the same, your choice), 1 vcc (all the same, your choice), 3x AD (exactly AD1, AD2, AD3). AD's are the signal pins.
On that very very useful tables you can find also the input diagrams of many Sega racers, so you can try to wire up an almost "universal" setup: steer, gas, brake, and "turbo".

Right now I have wired 1x 6 button joystick (I use it for credit, start, view change) and my modded MC2 wheel (steer, gas, brake, turbo).

If I can help more just tell me (sorry for my english).

JKL