2button and 6button gamepad schematic

[Bonknuts]

 WIP. Just need to connect the pins to the controller port. Y0-Y3 is data out to the PCE. Select and OE/CP are the 2 bit inputs (output from the PCE). I did a quick measurement of the resistors in place, so that's why they're probably ~45k. They're probably 47k resistors, but it makes no difference. They're just pull-up resistors to interface the CMOS I/O logic chips with the cpu.

 This is from the actual PCB I have. I don't have a 6 button pad, so I can exactly replicate it via schematic. But I have a very good idea exactly how it works. I'll be over the TAP 6button read code to verify my design, then I'll draw it out and built it from scratch and see how well it functions (four '157s and one '163).

 Edit: Didn't fix the the 2button schematic yet, but I worked out a 6button compatible circuit.

 6 Button layout:


 I used a 4th 157 to redirect autofire. The problem is that the TAP does auto Reset (D1). And since you need to re-read the pad again to gain the additional buttons, the counter used for autofire gets clocked twice. So instead of using Q1/Q2, I used Q2/Q3 of the 4bit output. This keeps autofire at the same rates as two button mode. Also, Q0 bit clock is used to select which chip. I still need to see if this is how the original 6button pad does this, or if there there's a bistable input switch on reset instead. The idea is; Reset is asserted to reset the TAP back to port 1, but also outputs to the PAD port 1. This in turns clocks the '163. Like SF2, to read the second set of buttons - the TAP is reset back to port 1 via D1 (reset on/off) - thus the '163 is clocked again and the second set of buttons of the '157 are selected. With the 2button switch, everything is bypassed and used as normal.

 I have quick a few junk Genesis pads (really back). They have '157s in them too. So I plan to build out this circuit on the bread board and test it out on SF2 and my own 6button read test code.

[BlueBMW]

Very nice!  That schematic will certainly be useful!  Though a six button schematic would also be very nice to have!

[Bonknuts]

Updated with WIP 6button schematic.

[soop]

Updated with WIP 6button schematic.

This is interesting.  Although, I have to say I'm barely able to comprehend your level of expertise.

[Bonknuts]

You would probably get rid of one of the '157s in the 6button schematic if you have a correct physical two position (multi input/output) switch that can handle enough lines. The '157s are nothing more than electronic switches themselves.

 I've built the 2 button circuit on a bread board yesterday and tested it out (updated layout from what I posted), and it worked out fine (though I didn't add in turbo yet). I've got PS2/PSX arcade stick that I'm gonna use to test out a 6 button version of the same over the next few days. Once I do, I'll finish up the schematics along with the correct pin output (not all controller cords have the same pin order on the PCB) and the correct caps.