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gamepad not working after SuperCIC mod
http://forums.nesdev.com/viewtopic.php?f=12&t=16352
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Author:  eadmaster [ Sat Aug 12, 2017 7:10 pm ]
Post subject:  gamepad not working after SuperCIC mod

hi, i have this PAL SNES SNSP-CPU-02 board with the SuperCIC installed (see the attachment).
Games boot fine and region-forcing with the reset button seems to work fine as well.
The only problem is the P1 controller is not working!
I've double-checked the connections to the front panel with a multimeter.
I've also checked the P1 controller port: the 5V pin is fine, while on the Clock pin i get around 50-60Hz with no controller attached (same as the Latch pin).

Attachments:
File comment: motherboard front
P1060433.JPG
P1060433.JPG [ 3.27 MiB | Viewed 644 times ]

Author:  lidnariq [ Sat Aug 12, 2017 7:49 pm ]
Post subject:  Re: gamepad not working after SuperCIC mod

Try testing continuity to a controller, not just to the jack.

If you have a 'scope or logic analyzer, the various control signals should look like:

Code:
OUT  __'__________________ ... [repeat every 16/20ms]
CLK  ____''''''''''''''''_ ...
D0   __ʎ=XXXXXXXXXXXλ_____ ... (only with standard controller plugged in)

Author:  eadmaster [ Mon Aug 14, 2017 4:13 pm ]
Post subject:  Re: gamepad not working after SuperCIC mod

I've checked continuity with a controller and it seems fine.
Unfortunately i don't have a logic analyzer, but i do have a multimeter with a frequency measure mode.

So i've checked the S-CLK chip which i had some issues while soldering.
All frequencies matches the nocash specs, except pins 1 and 2... do you know if these are related to the controller clock?

Author:  lidnariq [ Mon Aug 14, 2017 5:00 pm ]
Post subject:  Re: gamepad not working after SuperCIC mod

Pins 1 and 2 are analog signals from the actual crystal driver. As such, they won't reach full CMOS voltages. But the very presence of 21.28MHz means that it's working.

Apparently it was easier to use a 4×PAL crystal and a custom-made extra IC that both multiplies 17.7MHz by 6/5 (to generate the master clock) and divides it by 4 (to generate the colorburst clock); in contrast the NTSC deck instead starts with a 6×NTSC crystal to generate the master clock and S-PPU2 divides that by 6 to generate the colorburst clock.

Author:  eadmaster [ Mon Aug 14, 2017 5:19 pm ]
Post subject:  Re: gamepad not working after SuperCIC mod

what frequency should i read on the P1 controller Clock pin?

do you think there may be some bridges i should check?

(the P1 controller was working correctly before the mod)

Author:  lidnariq [ Mon Aug 14, 2017 5:37 pm ]
Post subject:  Re: gamepad not working after SuperCIC mod

Clock pin is active every 16/20ms (depending on region) but when it's active, it specifically goes high 16 times with supersonic spacing. Trivial to see on an oscilloscope or logic analyzer, but I don't think any other hardware is really up to the task.

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