MX29LV320 PCB (prototype) for SuperFX and CX4 Snes

[hidden0]

So i have been trying to make a PCB for MX29LV320 PCB for SuperFX and CX4 Snes since the AM29f032 are so expensive now.
MX29LV320 Tssop 48 chips are much more accessible and cheap so i took the retro stage design and tried to make modifications cuz i have seen some you tubers selling these kind of things but i am not able to find any kind of opensource pcb designs.

Since MX29LV320 works with 3.3v , All i saw they were using the 2x Diodes , Or may be we can use some AMS117.

Code: Select all

https://www.youtube.com/watch?v=KFV6kH9SExA

I am attaching the Idea of prototype if that's can be done.

Help from more experienced people will be very helpful.

Attaching Both Source File for my work , For Attrium Designer as well as EasyEDA export file and gerbers.

[Ziggy]

You should not use 3.3v chips in this way. Bringing the voltage down on the Vcc line is not enough. All of the address, data and control pins switch between +5v and ground. So they will will be getting hammered with 5v while their max tolerance is less than that (4.something volts). At best, this will eventually burn out the chip. But at worst, it could cause damage to the SNES.

Do you need 32 Mebibit? Because you could use the 29F160 which is 5v tolerant and still in production. People have already made such an adapter iirc. If you need 32Mebibit, then you can stack two 29F160, people have done this already for the DIP socket, you could design one for the SOIC footprint found on the GSU boards.

[hidden0]

That’s why i came here fir advice but indunno how stacking works and how to wire them so may be i can design a pcb adaptor board with 2 x 29f016 if i can find any reference.

Can you tel me where i can start and how to wire 2x in the same pcb.

[Ziggy]

Well I don't think you could fit 2 TSOP48's on the same PCB, at least not with keeping the SOIC footprint of the GSU mask ROM. It *might* be possible if you used 1 normal and 1 reversed pinout, that's exactly what the reverse pinout is for. I see it referenced in the datasheet, but I never see it for sale. Maybe I'm not searching correctly? Or maybe they just stopped manufactured the reverse pinned one?

But by stacking, what I meant was using two of the same PCB, with a TSOP40 on each, and stacking one on top of the other. Tie all of the pins together, with the exception of /OE. You would take the /OE pin from each TSOP and use some 74 logic to select between them. Which 74 depends on what you want to do. If you have a single game that is larger than 16 Mebibit, then you would need it to span across two 29F160. In this case, you could use a 74LS139 (selects 2-4 PROMs) or 74LS00 (selects between 2 PROMs). Both of these are standard for SNES carts, so you should have no problems finding a schematic or wiring diagram.

But are there any GSU games larger than 16 Mebibit? IIRC, there aren't. So if you need larger memory than 16 Mebibit, then I'm assuming it's to make a multi cart. In which case you would want to use a 74LS74, which you can wire up to select between two PROMs. Or a 74LS161, which you can use to select between 2 and 4 PROMs. They can be wired so that the console's reset signal switches between games. Both of these 74's are pretty standard for making multicarts in this way, so finding a schematic or wire diagram should be easy. If you didn't want the reset function to control switching games, you could also wire the /OE pins up to a physical switch.

Just realized you also mentioned the Cx4. This chip was only used for two games: Mega Man X2 and X3. So if you need more than 16 Mebibit for Cx4, then it must be because you're making an X2/X3 multicart. And if that is the case, someone has already made an adapter that'll let you use a 27C322 and select between both games by resetting the console.

https://arthrimus.com/how-to-make-a-cx4 ... x2-and-x3/



edit: Also note the difference between 29F016 and 29F160...

29F016 is a 16 Mebibit 40-pin TSOP chip that is 5v tolerant with an 8-bit data bus, but is no longer in production.

29F160 is a 16 Mebibit 48-pin TSOP chip that is 5v tolerant with a 16 or 8-bit data bus and is still in production.