# Gameboy Pokemon Cartridge Upgrades



## wadeVillines (Oct 19, 2017)

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]


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## wadeVillines (Oct 25, 2017)

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.


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## MichiS97 (Oct 25, 2017)

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


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## wadeVillines (Oct 25, 2017)

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.


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## wadeVillines (Nov 1, 2017)

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.


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## wadeVillines (Nov 22, 2017)

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.


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## wadeVillines (Nov 30, 2017)

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!


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## migles (Nov 30, 2017)

wadeVillines said:


> 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?


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## wadeVillines (Nov 30, 2017)

migles said:


> 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.


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## migles (Nov 30, 2017)

wadeVillines said:


> 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?


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## wadeVillines (Nov 30, 2017)

migles said:


> 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.


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## migles (Nov 30, 2017)

wadeVillines said:


> 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


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## wadeVillines (Dec 1, 2017)

migles said:


> 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).


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## CMDreamer (Dec 1, 2017)

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.


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## gnmmarechal (Dec 1, 2017)

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


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## ov3rkill (Dec 1, 2017)

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?


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## wadeVillines (Dec 1, 2017)

ov3rkill said:


> 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.


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## wadeVillines (Dec 1, 2017)

.


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## how_do_i_do_that (Dec 1, 2017)

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.


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## wadeVillines (Dec 1, 2017)

how_do_i_do_that said:


> 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.
> 
> 
> 
> ...



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.


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## Plstic (Dec 1, 2017)

Looks like a good design, Pokemon games always go dead fast. My yellow version died in 2002 lol.


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## gnmmarechal (Dec 2, 2017)

how_do_i_do_that said:


> 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.
> 
> 
> 
> ...


Iirc, some of the bootleg GBC carts I owned had similar ones, and replacing the battery was really easy.

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Plstic said:


> Looks like a good design, Pokemon games always go dead fast. My yellow version died in 2002 lol.


My Blue cart is still alive


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## placebooooo (Dec 2, 2017)

Bro, that was pretty sick. Good for you that it worked out!!


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## how_do_i_do_that (Dec 2, 2017)

wadeVillines said:


> 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.


The battery retainer picture I linked supports 2025, 2032 sized batteries.

If you want something smaller, like a 12XX sized battery. Something like this one will do, wich supports 1216, 1220 or 1225:




Source link


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## wadeVillines (Dec 10, 2017)

I had originally wanted to use a full size 20mm battery in this cartridge, but there just isn't enough surface area to fit everything in. The real time clock cartridges use a lot more components than other cartridge types, so space is VERY limited. There also aren't any good 16mm battery retainers that I could find that meet both the height and the surface area requirements, so it will have to be bumped down to a 12mm battery for the time being. This isn't too bad because the battery is ONLY used to keep the clock ticking. When it dies, the save data will be kept intact and only the clock will need to be set again. Even with this drop in battery capacity, the battery should last for plenty of time. 

However, I did find another version of the same flash chip I'm using (same chip, different package) that takes up way less surface area. For those interested, it is the version of the AM29F016 in a TSOP 40 (or 48) package. If this chip is used, it may be possible to fit a 20mm battery on this board, possibly up to a 2032, which was even larger than the original stock battery. This will take time to develop, but it's moving along at a steady pace.

Good news: my second revision came in and it is an improvement on the last one. I am wrapping up what looks to be the final revision today. If everything works (clock, saving, etc.) I should be prepared to release this project so people can start making their own.


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## gnmmarechal (Dec 10, 2017)

wadeVillines said:


> I had originally wanted to use a full size 20mm battery in this cartridge, but there just isn't enough surface area to fit everything in. The real time clock cartridges use a lot more components than other cartridge types, so space is VERY limited. There also aren't any good 16mm battery retainers that I could find that meet both the height and the surface area requirements, so it will have to be bumped down to a 12mm battery for the time being. This isn't too bad because the battery is ONLY used to keep the clock ticking. When it dies, the save data will be kept intact and only the clock will need to be set again. Even with this drop in battery capacity, the battery should last for plenty of time.
> 
> However, I did find another version of the same flash chip I'm using (same chip, different package) that takes up way less surface area. For those interested, it is the version of the AM29F016 in a TSOP 40 (or 48) package. If this chip is used, it may be possible to fit a 20mm battery on this board, possibly up to a 2032, which was even larger than the original stock battery. This will take time to develop, but it's moving along at a steady pace.
> 
> Good news: my second revision came in and it is an improvement on the last one. I am wrapping up what looks to be the final revision today. If everything works (clock, saving, etc.) I should be prepared to release this project so people can start making their own.


Glad to hear that it is going well!


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## wadeVillines (Dec 27, 2017)

Small update: finished the next revision. Some parts had to be moved around so the cartridge would completely close, and the clock didn't keep accurate time before. Hopefully the clock issues have been corrected in this version. If so, then this cartridge should be pretty much finished.

More to follow.


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## Cerdoinculto (Mar 29, 2018)

Excuse me, could you help me with the specification of capacitor Y1?


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## cearp (Mar 29, 2018)

any updates? @wadeVillines


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## wadeVillines (Mar 30, 2018)

cearp said:


> any updates? @wadeVillines


Perfect timing. The design underwent major changes, which I actually just finished yesterday. I was able to fit a 20mm battery on there, which is a big upgrade from the 12mm I was planning to use. You may notice there is an extra chip on this board, and that is a 3-input OR gate that is needed to enable/disable RAM access correctly. All that is left now is to order the board and test it. I did extensive testing when I assembled this circuit on a breadboard, so I'm pretty hopeful.

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Cerdoinculto said:


> Excuse me, could you help me with the specification of capacitor Y1?


Yes, that is actually a crystal, not a capacitor. This part is used to count seconds for the real time clock.
The most important thing is that you choose a crystal that has a 32.768 KHz frequency.
The next thing is choosing the correct capacitors to go along with your crystal.

The formula for this is CL = ((CX1 x CX2) / (CX1 + CX2)) + Cstray
CL = load capacitance of crystal
CX1 = load capacitance of capacitor 1
CX2 = load capacitance of capacitor 2
Cstray = the "parasitic capacitance" of your crystal circuit (in our case the circuit from the MBC, to the crystal, and back to the MBC)
Cstray doesn't matter too much, and can usually be estimated as anything from 0 - 5.
Also, I believe it is good to choose the same values for CX1 and CX2, at least in this case.
So knowing this, I found a crystal with a load capacitance of 12.5 pF, and two capacitors with 15 pF.
I don't know exactly how important this is, but for these capacitors, I made sure to find ones that had 1% tolerance, meaning they will always be within 1% of their rated capacitance.

The resistor for the crystal is a 330K resisitor.


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## wadeVillines (Apr 13, 2018)

Looks like it works. The clock, the FRAM, everything. Those gerber files will be uploaded soon!


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## migles (Apr 13, 2018)

wadeVillines said:


> Looks like it works. The clock, the FRAM, everything. Those gerber files will be uploaded soon!


can you tell what you have done? had you made the custom PCB? or moded the original one?


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## wadeVillines (Apr 13, 2018)

migles said:


> can you tell what you have done? had you made the custom PCB? or moded the original one?


Yes, it is a custom pcb with an authentic mbc3 chip and an fm18w08. i have added an OR gate to the board that takes the clock signal and the RAM_CS signal and use that output as the RAM chip enable.


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## wadeVillines (May 23, 2018)

OK, I think this project is ready for release. I have made a simple website to host some simple projects from, which is where you can find the gerber files for this project! You should be able to send the gerber files to a manufacturer and have them make the pcb for you. I recommend oshpark if you want cheap, but if you want durable, order from somewhere in china with gold plated cartridge connectors.

Website is RetroReboot.net. Thanks for your patience!


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## growl (Jul 30, 2018)

@wadeVillines

How did you flash the cart after putting it together? Can you recommend a compatible reader/writer?


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## JS7777 (Aug 5, 2018)

growl said:


> @wadeVillines
> 
> How did you flash the cart after putting it together? Can you recommend a compatible reader/writer?


Here you go : https://www.insidegadgets.com/projects/gbxcart-rw/


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## Toasty (Aug 30, 2018)

JS7777 said:


> Here you go : https://www.insidegadgets.com/projects/gbxcart-rw/


Thank you so much for this! This project is really cool, but a bit over my head. The OP doesn't seem to be interested in selling these himself sadly (but it's cool watching his work nevertheless!) I really need one of these writers so I can play my virtual console saves on my real hardware to play Stadium. This is possible, correct? Like I can extract the save with checkpoint?


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## JS7777 (Aug 30, 2018)

Toasty said:


> Thank you so much for this! This project is really cool, but a bit over my head. The OP doesn't seem to be interested in selling these himself sadly (but it's cool watching his work nevertheless!) I really need one of these writers so I can play my virtual console saves on my real hardware to play Stadium. This is possible, correct? Like I can extract the save with checkpoint?


I don't know what you mean by checkpoint but yes you can extract the saves from any carts.


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## cearp (Aug 30, 2018)

Toasty said:


> Thank you so much for this! This project is really cool, but a bit over my head. The OP doesn't seem to be interested in selling these himself sadly (but it's cool watching his work nevertheless!) I really need one of these writers so I can play my virtual console saves on my real hardware to play Stadium. This is possible, correct? Like I can extract the save with checkpoint?


https://bennvenn.myshopify.com/collections/frontpage/products/reader-writer-gen2?variant=51157011156
He's out of stock now, but sign up for email alerts. 
I have this and it's very good.


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## Toasty (Sep 4, 2018)

cearp said:


> https://bennvenn.myshopify.com/collections/frontpage/products/reader-writer-gen2?variant=51157011156
> He's out of stock now, but sign up for email alerts.
> I have this and it's very good.


Thank you for the link; this website is very interesting, definitely bookmarking it.


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## XR4CK (Nov 13, 2022)

Hello, I am new here in the formus and I have one important question. I have been researching a lot but the only closest topic I could find was this one here! I do repair these old original cartridges and I noticed on one Pokemon Crystal, that the *C4 capacitor* is missing. 


Can somebody explain me its function (because the game also works without it, and also saves the game!)? 
Does also someone know the exact value of this little component in order to replace it?

Greetings!


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