Author Topic: Saturn PAD to JAMMA Ver 1.1  (Read 4001 times)

Offline l_oliveira

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Saturn PAD to JAMMA Ver 1.1
« on: June 20, 2009, 02:20:41 am »
Found out that I left an important part of the device out of the schematic I posted on this thread:
http://nfggames.com/forum2/index.php?topic=3686.0

Also, a few improvements have been done:
The pull up resistors for the latches inputs were missing. This could cause *all* buttons to appear as 0 (pressed) on each player if no SEGA SATURN controller was connected.
2x 100 ohm resistors were added to the PADs 5v to prevent fires in case of short circuit on the controller cables.  (I think only 3rd party pads have chance of ever doing this
but better safe then sorry)
1k ohm resistors added to S0 and S1 address lines to diminish addressing errors with longer controller cables. (signal echoing)



On a side note, I'm thinking about "developing" an version for the SEGA Mega Drive 3 buttons pad (probably for the PC-Engine pad too as these controllers use the same sort of logic on their design)
(Concept block diagram on the attachments)
Such controllers (the PC-Engine one most notably) is best suited for 2 button shooters such as:

Toaplan/Taito:  Twin Cobra/Kyukyoku Tiger   Truxton/Tatsujin
Irem's R-Type series
Taito's  Scramble formation/Tokyo
Seibu's Raiden
Nihon Bussan's Terra Cresta


I have a feeling that playing these ARCADE games on a PCE PAD would be very much a form of bliss.

If I get hold of a few 74LS164 chips I might try decoding NES/SNES pads too...

Lastly I'd like to thanks all people related to the SEGA SATURN PAD schematics, for posting it here and allowing me to see it. It was a great source of inspiration.

Offline l_oliveira

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Re: Saturn PAD to JAMMA Ver 1.1 (Updated to 1.2)
« Reply #1 on: July 03, 2009, 12:55:42 pm »
A small change on how the pads are read. Now the binary counter is wired in a way that make  the latch get clock pulses twice per state.
This greatly increased the reliability of the circuit and allowed me to get rid of the ugly hack with the LEDs.

A special thanks for Calpis from Assemblergames who gave me the insight on how to solve this problem.