Modifying Genesis controller to use start button as pause on Master System

Discussion in 'Sega Discussion' started by Friend of Sonic, Mar 18, 2016.

  1. Friend of Sonic

    Friend of Sonic Spirited Member

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    I found a Youtube video with a guy demonstrating a Genesis controller pausing Master System games, but can't find any instructions. Would love to do this to my Gen controller-- does anyone have any information? All I could find was a guide to add a button to the Master System pad.
     
  2. abveost

    abveost Peppy Member

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    Was it 3 or 6 buttons? Was the game modified?
     
  3. Friend of Sonic

    Friend of Sonic Spirited Member

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    Three button controller. Certainly doesn't appear to be a flash cart using a modified ROM.
     
  4. jamespoo

    jamespoo Peppy Member

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    wow that looks cool never knew that could be done
     
  5. Gentlegamer

    Gentlegamer Active Member

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    I believe you just use the instructions to add "pause" to a Master System pad, just tied to the Genesis pause button (that controller becomes your dedicated Master System pad).

    The modification provides a way to add a pause button on SMS joypads with no rewiring and minor modifications on the power base's side. It works by tying two opposite directions of the pad to ground, making an "impossible" combination which can be detected to trigger an NMI.

    http://www.smspower.org/Development/JoypadPauseButton
     
  6. Friend of Sonic

    Friend of Sonic Spirited Member

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    I'll give that a shot, thanks!
     
  7. TriState294

    TriState294 Site supporter 2016

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    That strategy would require you to mod both the Master System itself and the Genesis controller. It would be one mated pair of modded kit.

    The slicker way to do this would be to demodulate a stock Genesis controller input inside the Master System. Then you could use any Genesis controller with it.
     
  8. Friend of Sonic

    Friend of Sonic Spirited Member

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    The latter part intrigues me...!
     
  9. abveost

    abveost Peppy Member

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    The SMS didn't have a multiplexed controller so SMS games wouldn't toggle the select line. In that case the Genesis controller will only output one set of signals. You'll never get the start button status unless you set select low.
    The easiest way to do this on a SMS would be to run the start button over the unused line on the controller port to the pause button in the console. Probably wouldn'y want to use that controller on a Genesis since that line is 5V, unless you put in some extra bits to detect what system you're plugged in to.
     
  10. Friend of Sonic

    Friend of Sonic Spirited Member

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    I have zero issues dedicating a Genesis controller for this purpose. They're not too expensive after all.
     
  11. TriState294

    TriState294 Site supporter 2016

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    That would work, but is essentially just the same pause mod as the wiki shown above except starting with a Genesis controller instead of adding a button to a Master System controller. It would require both the console and the controller to be modded.

    The SMS Power wiki seems to suggest that the select line is toggled in certain cases, but other docs seem to say that it not. I'd really like to look into this when I get the time, but I'm not the most experienced with dealing with logic chips.
     
  12. l_oliveira

    l_oliveira Officer at Arms

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    Export Master System units were designed later so they have a slightly better (it has two programable bidirectional pins) controller port. SG-1000 MKIII and consequently the Japanese Master System have a less capable controller port (and actually the region detection involves detecting the presence or not of the advanced controller port) and on Japanese machines, the bidirectional pins are simply wired to GND.

    That also happens to be why there is no SMS gun games in Japan.

    So modding games for this would only work on non Japanese SG-1000 MK-III/SMS and I suppose that's what the wiki meant to say.
     
  13. Friend of Sonic

    Friend of Sonic Spirited Member

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    Very interesting information.

    I'm actually waiting on my controller to come in the mail. Hopefully I can try things out soon.
     
  14. segasonicfan

    segasonicfan Robust Member

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    I don't think there are any "unused" pins in the SMS controller port, fyi. The often cited as "unused" pin 7 is actually TL and it required for lightgun games. Pin 5 is often left blank but this is actually +5v out and is also needed for lightgun games. Found this out the hard way and wanted to slap the people circulating the wrong info.

    -Segasonicfan
     
  15. Friend of Sonic

    Friend of Sonic Spirited Member

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    Oh! Dang... I guess I am out of luck? I wouldn't say sacrificing lightgun support is worth a pause button button.
     
  16. segasonicfan

    segasonicfan Robust Member

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    afraid so....unless you did some multiplexing of one of the signals, it is not possible to have both!
     
  17. thunderid

    thunderid Newly Registered

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    I was thinking if it was possible to put an AND gate to see when select and start are active and then use this signal to pause the Master System, modding only the console. But from what I understood the system have to send the select signal to the controller. So I modification needed to be made to send this signal and read the outputs from the controller, but that would mess up the reading of the other commands,

    Maybe some kind of converter could be made by sending all the information to a microcontroller and then from the microcontroller to the console, but that would probably input some lag. Maybe this would be worth implementing with a bluetooth controller for both systems, since you would have some kind of lag anyways.
     
    Last edited: Jun 20, 2016
  18. l_oliveira

    l_oliveira Officer at Arms

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    Fujitsu does this on the FM Towns controller:

    Since it's impossible to push up+down and left+right at once it uses these two pairs of signal pins (with diodes) to signal the select/start buttons on it's controller.

    Modding the controller that way and putting a micro controller inside the console to catch these signals could work. But some games could behave erratically to these weird/opposing button presses.
     
  19. Yakumo

    Yakumo Pillar of the Community *****

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    I have a Master System converter for the Mega Drive which doesn't feature an PAUSE button. Would there be a possible way to add such a button to the converter?
     
  20. l_oliveira

    l_oliveira Officer at Arms

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    The pause button is a signal on the slot connector, so yes it is possible.
     

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