RoadBlasters JAMMA / GamePad Conversion Success!

FlashShift

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Have started working on a JAMMA adapter for RoadBlasters, and I wanted it to work with a gamepad or joystick, so that I don't have to connect a steering yoke. So far, have made some great progress. The optical board pulses CLK and DIR pins on J103, but the game expects a specific ordering of the optics. The two pulses interleave in order to steer, and depending on the interleave of those pulses, you go either left or right. I implemented a test circuit on a breadboard with an NE555 timer combined with an RC delay circuit (resistor+capacitor) so that the first pulse is clocked, and the second pulse is just behind it. Success! And to reverse the pulse, I just invert the signal. Depending on how the DIR pin pulses first determines the direction.

Going to tie this to some gamepad buttons next, and test the steering. The longer you hold the pad down, the more it will veer into a given direction. One problem I can see with this is there's presently no return to zero. I'll most likely need to add an 8-bit counter to the circuit, and trigger it to count/clock backwards whenever a button is released until it reached zero (or 127, or whatever). Synchronizing this with the game may be tricky.

Anyway, thought I'd share this - have always loved this game, and would really like to get it going on my jamma+gamepad "coffee table" setup.
 

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Makeshift JAMMA adapter working. The steering wheel interface fits on a potato chip. It's a timer circuit with an RC delay for the DIR pin, and inverts the signal depending on direction. Works a lot smoother than mame.
 

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boards came in today. I ended up using a 224 for the timing cap instead of the 0.47 uf and now the steering speed is right on. The negative voltage boost inverter delivers -12V straight to the system 1. op amp working nicely. DM me if you're interested in a board.IMG_3130.jpeg
 
The point is to be able to eliminate the steering yoke and play with a joystick or gamepad, whether that's on a coffee table or a cabinet :)
 
Having loved the original long ago I'm not predisposed to think of it without wheel and pedal but this is a really cool project all the same.

I think Road Blasters may have been the only golden age racer that used its particular type of optical wheel actually, making a hack of some sort even more of a viable effort.

Cool work.

Let's see it built out and playin!
 
I have a Roadblasters, and adore the game. I also have owned a few Ultracades over the years and Roadblasters is one of the licensed games they have which i tought was odd since none of those cabinets ar set up for wheels. I found that playing it with a arcade stick and buttons replacing the whieel, pedal, and triggers that it wasn't much fun. Really one of the controls makes the game kind of games.

But that said, I agree with @bobbyb13 that the project itself is pretty neat. And i look forward to seeing your updates.
 
Sure, different blokes different strokes. I grew up on Rad Racer, and a few adaptations of Roadblasters using a gamepad so I'm more comfortable with it. But mainly, steering yokes available these days are pretty rusted out, poorly cared for, and pretty expensive so unless you're using a dedicated System 1 cabinet, it may be more feasible to enjoy the game with joystick/gamepad controls.
 
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