help with sega gen controller pcb

[ulao]

Hi al I tried to make a pcb to emulate my sega 6 button but I have two issues.

1) I'm not getting the higher buttons  x,y,z
2) up and down are alternating when either re pressed.

pretty sure (2) is because up and down are connected to the other multiplexers. Since something is wrong they are showing osculations. but I'm not sure what I did wrong with (1), maybe my counter set up?




this was my go a it. Can anyone spot my mistakes?

this was based on @KillingBeans design in  https://nfggames.com/forum2/index.php?topic=2266.0

[ulao]

I think I see the issue (s)

either 1 or both.

1) Timing changes all of this, you need to plug it in when its not pulsing. Good bet it will be right for 3 button but 6 button is very tricky.

most of the time I get this plugging in for 6 button mode.

top my circuit
bottom oem.


2) The 1qc is wrong, for clear state. move to 2qc because of that the clocking was out of sync.


as a note of concern make sure to read the propagation timing for the parts. Keep it all under 50ns or so. Sega will allow some drift but not must. I think 300ns is the max value.

[ulao]

Ok I solved the (1) by adding a switch. You can add a cap to add the de-bounce but I didn't have to. I just added a switch from +5 to clear. Plug it in, then switch from clr holding high, to released. I hit it most every time now. All the bouncing of plugging in the controller was messing up the clocks.

 

[ulao]

yes, these changes worked, and with switch form 3 to 6 button mode works.