Gameboy Pokemon Cartridge Upgrades

[wadeVillines]

Hey,

I have been wanting to upgrade my Gameboy (mostly Pokemon) cartridges to use non-volatile RAM so that my save files don't disappear anymore when the battery dies. The best replacement RAM chip that I have found is the FM18W08. The only problem is, to make this chip work as a drop-in replacement, a 10K resistor must be used to connect the voltage supply pin (Vcc or Vdd) and the chip enable pin (CE).

Once in place, the battery could actually be removed from the cartridge and the game would still retain save data. Of course, if the game uses a real-time clock, the clock won't run while the console is turned off if there is no battery in there.

Seems simple enough, right? The only issue is, I hate the way an axial resistor looks when it's soldered in, and would like a more professional-looking solution. A surface-mount resistor would look great, but this would require editing the cartridge design to fit one in.

That's what we're gonna do.

[Edited for clarity]

 

[wadeVillines]

I have decided to take this into my own hands. I sat down with my trusty multimeter and this is what I have come up with so far for the RAM chip.
The C4, C5, and C6 refer to capacitors on the circuit board.

Maybe there will be more to follow.

 

[MichiS97]

As an electrical engineer, this seems pretty intriguing to me. What exactly do you want to accomplish with that modification?

 

[wadeVillines]

I am replacing the volatile SRAM chips in my gameboy cartridges with non-volatile FRAM chips. I want to use FRAM so I can do away with the coin cell battery. The only issue is that I need a pull-up resistor attached between the voltage pin and the chip-enable pin of the FRAM chip to accommodate the way FRAM does address latching. I wasn't satisfied with soldering in an axial resistor because the end result looked kind of ugly compared to what a surface mount resistor would look like.

The chip I am using is the FM18W08. Details about using the pull-up resistor are in the datasheet.

 

[wadeVillines]

Made a fair bit of progress. Created my schematic in DipTrace and converted it to the following PCB file. All that's left to do is route and manufacture (hopefully). This PCB has been modified to use an AMD flash chip so it can be reprogrammed as any gameboy title that is less than 2 MB in size. Also, the battery contacts have been adjusted to allow a battery holder to be installed. Finally, a resistor has been added so that F-RAM (non-volatile RAM) can be used.

 

[wadeVillines]

It's been 3 long weeks, but I think I have my first prototype ready. I have already ordered 3 copies of this from a fabricator. (This is actually my second revision, I wasn't happy with my first one).

Until next time.

 

[wadeVillines]

Cartridge is finished. It works! I still have some minor adjustments I want to make to this design before I’m done, but this is a big win today. I will be releasing my board design to the public so anyone can order this board for themselves! Thanks for watching!

 

[migles]

Cartridge is finished. It works! I still have some minor adjustments I want to make to this design before I’m done, but this is a big win today. I will be releasing my board design to the public so anyone can order this board for themselves! Thanks for watching!
View attachment 107304

looks awesome! it's funny how when i hear about a bootleg, i usually refuse the idea, because i do love stock as possible.
but this "bootleg" which is an upgrade to the original, seems something i am looking for..

is this compatible with the pokemon stadium\n64 transfer pack games? do you accept orders directly?

 

[wadeVillines]

looks awesome! it's funny how when i hear about a bootleg, i usually refuse the idea, because i do love stock as possible.
but this "bootleg" which is an upgrade to the original, seems something i am looking for..

is this compatible with the pokemon stadium\n64 transfer pack games? do you accept orders directly?

Unfortunately, I don't have the resources right now to supply these cartridges. Once I move into a house from this apartment (shouldn't be too long), maybe I can sell a few. I will post on here if I do.
I haven't been able to test with Pokemon Stadium yet, but the graphical glitches are fixed, so I would assume the Stadium issue is fixed as well, since they were caused by the same problem.

 

[migles]

Unfortunately, I don't have the resources right now to supply these cartridges. Once I move into a house from this apartment (shouldn't be too long), maybe I can sell a few. I will post on here if I do.
I haven't been able to test with Pokemon Stadium yet, but the graphical glitches are fixed, so I would assume the Stadium issue is fixed as well, since they were caused by the same problem.

btw, i noticed you swaped the rom chip?
does this means, we can't use a donor cartridge to use it's mcb+rom in this pcb?

 

[wadeVillines]

btw, i noticed you swaped the rom chip?
does this means, we can't use a donor cartridge to use it's mcb+rom in this pcb?

Correct, this is actually a re-programmable chip instead of a ROM chip. It can be programmed to be any game that is 2 MB or less in size. Taking this design and making it use original ROM chips would be an easy step, though. The design would be a good deal simpler.

 

[migles]

Correct, this is actually a re-programmable chip instead of a ROM chip. It can be programmed to be any game that is 2 MB or less in size. Taking this design and making it use original ROM chips would be an easy step, though. The design would be a good deal simpler.

can you use this guy's gbx reader to write your custom card? https://www.insidegadgets.com/projects/gbxcart-rw/
he is very cool, i had purchased that gbx reader, chatted a while with him via email, he is very friendly and likes to help

 

[wadeVillines]

can you use this guy's gbx reader to write your custom card? https://www.insidegadgets.com/projects/gbxcart-rw/
he is very cool, i had purchased that gbx reader, chatted a while with him via email, he is very friendly and likes to help

Don't quote me on it, but it should work just fine. I'm sure he could give you a definite answer. Just tell him it's an AM29F016 Flash chip. If it can write other flash carts, then I imagine mine should be no problem.
EDIT:
I forgot to tell you that you can use an MBC from a donor cartridge, just not the original ROM chip. (In fact, a donor cartridge is the only way to get the MBC without making a custom one).

 

[CMDreamer]

Now this is something that makes me fell grateful to know about. The designs looks pretty "simple" (not easy), and being it reprogrammable it makes for an awesome upgrade!

Thank you for willing to share the final design, I'm looking forward for it.

 

[gnmmarechal]

Wow, this looks neat. This is something I'll be paying attention to.

 

[ov3rkill]

Haven't looked into the details yet. This reminded me of this one (http://www.reinerziegler.de/readplus.htm). Hopefully, you can share new details too since this is new, updated and interesting. How much did it all cost, PCB and components?

 

[wadeVillines]

Haven't looked into the details yet. This reminded me of this one (http://www.reinerziegler.de/readplus.htm). Hopefully, you can share new details too since this is new, updated and interesting. How much did it all cost, PCB and components?

Once I get all the flaws hammered out, I would really like to make a proper blog so anyone can do this for themselves, or use the board files I plan to post there. My last task is to squeeze a battery holder onto this board somewhere (the battery is still required to power the clock), but after that I hope to publish all the details.

 

[wadeVillines]

.

 

[how_do_i_do_that]

I would recommend a mod to the battery type that is being used on the PCB you have laid out. Instead of a tabbed battery requirement, a battery holder/retention clip to accommodate normal batteries would be better.

source link here

Other clips or holders if the above doesn't work for you.

This would reduce the maintenance cost for the user and a whole lot cheaper and easier to find a normal button cell. Reason being that not everyone that wants a flashcart can solder a new battery.

 

[wadeVillines]

I would recommend a mod to the battery type that is being used on the PCB you have laid out. Instead of a tabbed battery requirement, a battery holder/retention clip to accommodate normal batteries would be better.

source link here

Other clips or holders if the above doesn't work for you.

This would reduce the maintenance cost for the user and a whole lot cheaper and easier to find a normal button cell. Reason being that not everyone that wants a flashcart can solder a new battery.

That is an excellent suggestion, and is actually what I have planned to do. I have ordered 3 different kinds and am deciding which one I like best. I am one of those people that does not enjoy firing up my soldering iron just to replace one simple battery.