Breaking Out A Game Boy Link Cable

[Samuel] is working on one of the most important electronics projects of our generation. He’s building a device for the Game Boy that will allow Pokemon trades between generation II and III. Yes, This means bringing your Charmander from Pokemon Red to your team in Pokemon Ruby, Sapphire, or Emerald. and finally completing the National Dex you’ve been working on for 20 years. Before he gets to designing this system, he first needs to listen in on the Game Boy Link Cable, and that means creating a breakout board.

The Game Boy Link Cable – sometimes inaccurately referred to as the Zelda cable – is a special proprietary connector. The design is well documented, but unlike the Wii Nunchuck controller, there’s no readily available breakout board available for this piece of obsolete technology.

Together with a his friend [David], [Samuel] loaded up a copy of Eagle and designed a board that will fit on a small piece of copper clad FR4. This design was then sent over to a small CNC mill, The traces were machined away, and a sextet of pins were soldered into the holes.

With a breakout board for the Game Boy Link Cable, [Samuel] now has a great platform for peering into the strange and magical world of Pokemon. He’ll be using a Teensy microcontroller for his trading device, and with several similar projects already completed by others around the Internet, the potential for a Gen II to Gen III Pokemon trader is palpable.

17 thoughts on “Breaking Out A Game Boy Link Cable

  1. “He’s building a device for the Game Boy that will allow Pokemon trades between generation II and III. Yes, This means bringing your Charmander from Pokemon Red to your team in Pokemon Ruby, Sapphire, or Emerald.”

    uh.. Red is generation I

    1. Yes red is generation 1. However generation 1 allowed trading to the generation 2 games. Generation 3 games on the GBA can all trade between each other. The Gen 4 games on the DS also had a facility for trading with a gen 3 title via the GBA port and there are ways of trading between gen 4 and 5, also ways to trade between gens 5 and 6. Hypothetically I can catch a pokemon in pokemon ruby and trade it all the way through multiple copies of the games on a few consoles to bring it to pokemon Y on a 3ds (or even Omega Ruby if I wanted). For some people this is a desirable thing, but gen 3 is the oldest you can do it with. There is no way to trade from generation 2 to 3, once this is crossed, then yes, you can trade your team in pokemon red through to pokemon gold/silver/crystal and then through to ruby/sapphire/emerald, although my personal preference would be simply get firered/leafgreen which were the gen1 remakes in gen 3.

  2. The games had a large overhaul between Generations II and III. The data structure of Pokémon in each is completely different — things exist in Gen III that did not in Gen II, and vice versa. There already exist tools that “convert” between these by making assumptions.

    1. DIfferent pokemon game generations are different consoles. Generation 1 games were gameboy, 2 gameboy colour, 3 gameboy advance etc. Generation 1 and 2 can trade. There are ways of trading upwards through generation 3 onwards. But there was no way to trade between generation 2 and 3.

  3. Why not just cut the cable… and solder on headers to plug onto your teensy. I think this is over engineer.

    Actually Gen I games are ported to Gen III, namely firered and leafgreen, so Charmander on Gen III doesn’t need this. but this is still an interesting project. I would like to point you to the usb gba multiboot project by tangrs, which provides an open source implementation of bitbanging the GBA, and he uses Teensy too.

    I can only guess that will be a tremendous load of work to do to figure out the Pokemon transfer protocol. Good luck.

  4. Nintendo intentionally released LeafGreen and FireRed on the GBA so the Gen I Pokemon could make it to Gen III. They might have left out Gen II until SoulSilver and HeartGold, but all Gen I and II Pkmn are tradabel from Gen III and IV upwards respectively.
    That being said, I like the idea of taking ‘your original Pkmn’ from the very first pixel sprites all the way into the 3D sprite era.
    However, I don’t believe the coding in Gen I and II are compatible with III though (so they released FRLG based on RSE), so I’m guessing they’re probably aiming for a ‘read old Pkmn values in Gen I / II -> create new Pkmn with same values in Gen III’ approach..You could use a gameshark or similar device to achieve that without the cable.

    1. It obviously can be done. The trick is just to add in any factors that the old game doesn’t have, and remove any that the newer game doesn’t. To get the values, you could use all sorts of methods, perhaps a table of standard ones for the particular Pokemon. And of course you can cheat yourself up some Super ‘mons, if you wanted to.

  5. I always wanted to do this. Problem is that pokemon internal data is so different from generation II to generation III that he will need to made up some portions of this data. I’m talking about IV values and such.
    But yes, this is a very cool idea(:

  6. I’m not sure about this. II mean, it’d be great to get “my” mon from Gen 1 (yes I still have my cart), but I don’t know if they’d be the same once they cross from Gen 2 to Gen 3. The middle has to have some changes to the code as has been mentioned. I think the EV’s or something were twice as high. Or maybe it was IV’s. They could be 32 in Gen 1/2 and only 16 in Gen 3+. So either the mon traded up are modified to where they aren’t my mon anymore, or they’re kept with their stats, and therefore seem to be “hacked” and un-bankable. Kind of like how you can’t say absolutely whether or not I’m the same me on the other side of a destructive teleporter (Star Trek = destructive, StarGate = non-destructive).

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