Gamecube memcard emulator with arduino?

[GizmoTheGreen]

here's a wild idea...
make a custom memcard with an arduino(or compatible) which would be like an SD Gecko, but for regular games it acts like a memory card and writes the saves to a folder on the (micro) SD card....
when the arduino sees typical gamestuff communication it would respond as expected and emulate a memorycard, writing files to sd(fat,fat32, maybe exfat?)
otherwise it would do straight through SD coms for homebrew.

or it could just be a switch.

I gather it's doable?

Might seem like a bothersome project at first but there's a few good things if this was done.
1. Future proofing
We can make our own memory cards, with any size(or limitless!)
no longer reliant on third party cards from china for the future, who knows how much longer they'll be making them?

2. easy backup of saves to pc, just swap the sdcard in and out to PC, do what you want.

[novenary]

Arduino is not a good platform for this, you need an FGPA or a CPLD. It's definitely feasible, but it would be cheaper and easier to build memory cards with a USB connector. For arbitrarily large flash, you would also need some kind of bank switching mechanism.

[GizmoTheGreen]

huh.
since we're interfacing SD on the same io I figured an arduino could get the job done... apologies

[novenary]

The problem is that the memory card slots use a bus that is very similar to SPI (though not fully compatible). That works fine for controlling SD cards, but the speed at which memory cards are being driven is almost equal to the CPU speed on the Arduino, which makes it pretty much impossible to receive data from the cube on there.
You need a CPLD or an FPGA because the timing is relatively tight and sensitive even for a faster microcontroller to handle.
What you can do with an Arduino however is a separate device that could read and write to a real memory card and either make it standalone or integrate it with the card. Considering how easy it is to do using homebrew on a GC or Wii, it's not really worth the hassle.

[GizmoTheGreen]

Right, thanks for the elaborate information