Looks like a good design, Pokemon games always go dead fast. My yellow version died in 2002 lol.
Gameboy Pokemon Cartridge Upgrades
- Thread starter wadeVillines
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Iirc, some of the bootleg GBC carts I owned had similar ones, and replacing the battery was really easy.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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My Blue cart is still alive
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
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.
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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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.
More to follow.
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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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)
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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Last edited by wadeVillines,
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.
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!
Website is RetroReboot.net. Thanks for your patience!
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.
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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