Access MicroSD Card over USB-C?

[Zi0v4_]

Hey,
a few weeks ago, I started replaying my CFW Old 3ds XL and by being aware of the current hw mods, some ideas came to my mind and I was wondering if some of you may answer my questions :
Can a USB-C/A mod to transfer files to sd card by cable be possible ?
Same for a USB A OTG (to connect wired controller, headphone, USB Key, etc..) ?

If you have some more ideas for potential HW mods, write them below so maybe we can have answers and further researches..

 

[kijetesantakalu042]

A usb mod will only allow for charging

 

[Zi0v4_]

A usb mod will only allow for charging

But I was wondering if connecting a USB C breakout to the sd card slots test points or anything like that could allow file transfer

 

[kijetesantakalu042]

But I was wondering if connecting a USB C breakout to the sd card slots test points or anything like that could allow file transfer

USB and SD card are completely incompatible, you'd need some form of micro controller (or most likely FPGA) to allow them to communicate. I also don't even think there are test points on the 3DS's motherboard.

 

[Zi0v4_]

USB and SD card are completely incompatible, you'd need some form of micro controller (or most likely FPGA) to allow them to communicate. I also don't even think there are test points on the 3DS's motherboard.

Still is it possible ? For sure it's not gonna be light work, but my initial question was if the 2 mods I thought about were possible in a way or another

 

[Kwyjor]

Still is it possible ?

"Everything is theoretically impossible until it is done." -Robert A. Heinlein

 

[kijetesantakalu042]

Still is it possible ? For sure it's not gonna be light work, but my initial question was if the 2 mods I thought about were possible in a way or another

This issue also is race problems where a game wants to write or read something but the hardware won't allow it because it's writing data into the SD cards.

if you wanted to make it, you probably could, but don't expect someone to do it for you

"Everything is theoretically impossible until it is done." -Robert A. Heinlein

Said it perfectly

 

[The Real Jdbye]

USB and SD card are completely incompatible, you'd need some form of micro controller (or most likely FPGA) to allow them to communicate. I also don't even think there are test points on the 3DS's motherboard.

But I was wondering if connecting a USB C breakout to the sd card slots test points or anything like that could allow file transfer

Wire a USB MicroSD reader internally, it should be quite doable (of course never plug the USB in while the 3DS is turned on or you may have corruption)

Hey,
a few weeks ago, I started replaying my CFW Old 3ds XL and by being aware of the current hw mods, some ideas came to my mind and I was wondering if some of you may answer my questions :
Can a USB-C/A mod to transfer files to sd card by cable be possible ?
Same for a USB A OTG (to connect wired controller, headphone, USB Key, etc..) ?

If you have some more ideas for potential HW mods, write them below so maybe we can have answers and further researches..

USB OTG is a lot harder to do. Headphones are easy enough, you can wire an adapter internally. Controller support would need to have wires running to each button pad and you could probably use a Pi Pico or similar to accomplish the translation between USB host -> button inputs. But to support both through the same port, you wouldn't be able to use a simple audio adapter. Perhaps the Pi Pico is powerful enough to also act as a DAC for USB -> analog audio so it can accomplish both things. In any case it would not be a simple mod.
USB drives are probably not feasible, there's just no mechanism for connecting secondary storage to the 3DS, or mounting it in the software. And homebrew wouldn't know how to access it anyway. IIRC an adapter exists that allows you to plug a USB drive into a SD slot, but it's unstable with very slow data transfer rates and essentially useless, and even with an adapter like that, you wouldn't be able to use a SD card anymore. So the only way that it could work is by having a microcontroller handle both the USB drive, and the microSD, and merge the file systems, pretending to be a SD card to the 3DS so what the 3DS sees is the combination of both of their files. It's possible in theory but writing the code and making it all work reliably (and with decent speed) is a problem. This might be best done with a FPGA, I'm not sure if a Pi Pico could handle it. The PIO on the Pi Pico is powerful, but it only has 12 pins and you're already asking it to do a lot of things. I think asking it to do even more might exceed the capabilities. Any other microcontroller (that doesn't have an equivalent to PIO) would have no chance, they're only capable of connecting SD cards in the much slower SPI mode which is too slow for any significant data transfer.

 

[kijetesantakalu042]

(of course never plug the USB in while the 3DS is turned on or you may have corruption)

Which completely ruins the point. At that point just plug the SD card into your pc

 

[The Real Jdbye]

Which completely ruins the point. At that point just plug the SD card into your pc

Unless the point is to avoid taking the SD card out or bringing a SD card reader around with you.
But I agree, it's a niche mod with limited usefulness.

 

[TheStonedModder]

Wire a USB MicroSD reader internally, it should be quite doable (of course never plug the USB in while the 3DS is turned on or you may have corruption)

USB OTG is a lot harder to do. Headphones are easy enough, you can wire an adapter internally. Controller support would need to have wires running to each button pad and you could probably use a Pi Pico or similar to accomplish the translation between USB host -> button inputs. But to support both through the same port, you wouldn't be able to use a simple audio adapter. Perhaps the Pi Pico is powerful enough to also act as a DAC for USB -> analog audio so it can accomplish both things. In any case it would not be a simple mod.
USB drives are probably not feasible, there's just no mechanism for connecting secondary storage to the 3DS, or mounting it in the software. And homebrew wouldn't know how to access it anyway. IIRC an adapter exists that allows you to plug a USB drive into a SD slot, but it's unstable with very slow data transfer rates and essentially useless, and even with an adapter like that, you wouldn't be able to use a SD card anymore. So the only way that it could work is by having a microcontroller handle both the USB drive, and the microSD, and merge the file systems, pretending to be a SD card to the 3DS so what the 3DS sees is the combination of both of their files. It's possible in theory but writing the code and making it all work reliably (and with decent speed) is a problem. This might be best done with a FPGA, I'm not sure if a Pi Pico could handle it. The PIO on the Pi Pico is powerful, but it only has 12 pins and you're already asking it to do a lot of things. I think asking it to do even more might exceed the capabilities. Any other microcontroller (that doesn't have an equivalent to PIO) would have no chance, they're only capable of connecting SD cards in the much slower SPI mode which is too slow for any significant data transfer.

Loopy has schematics online for a PCB that allows an external GameCube controller that attaches to those test points

 

[Hayato213]

Hey,
a few weeks ago, I started replaying my CFW Old 3ds XL and by being aware of the current hw mods, some ideas came to my mind and I was wondering if some of you may answer my questions :
Can a USB-C/A mod to transfer files to sd card by cable be possible ?
Same for a USB A OTG (to connect wired controller, headphone, USB Key, etc..) ?

If you have some more ideas for potential HW mods, write them below so maybe we can have answers and further researches..

USB port I only seen for charging, and capture card purpose, not SD card, I seen people done wired controller connected to the 3ds.

 

[Zi0v4_]

in fact the mode is pure qol improvement for a small issue, but brings phone file transfer when either a laptop nor a SD reader are in your pocket. I plan on trying to code a microcontroller and maybe if it needs to, designing a pcb to connect every ends. Do you think a manual button switch could make the usb c reachable when the 3ds is on, the button would then switch from usb c wire, to 3ds wires

 

[Kwyjor]

Do you think a manual button switch could make the usb c reachable when the 3ds is on, the button would then switch from usb c wire, to 3ds wires

That depends entirely on you and your skill in coding a microcontroller and designing a PCB.|

 

[Zi0v4_]

That depends entirely on you and your skill in coding a microcontroller and designing a PCB.|

So it is theorically possible ? Ima try it then, how could I test it without breaking entirely my 3ds in case of an error

 

[kijetesantakalu042]

So it is theorically possible ? Ima try it then, how could I test it without breaking entirely my 3ds in case of an error

You could try to find a (preferably old) 3DS with a broken hinge. I'd also suggest researching FPGAs. It'd probably make your mod work faster.

 

[Zi0v4_]

You could try to find a (preferably old) 3DS with a broken hinge. I'd also suggest researching FPGAs. It'd probably make your mod work faster.

thank you for your help, I might update the build on a new thread when I get to start the project

 

[Kwyjor]

So it is theorically possible ?

Everything is theoretically possible! It's "possible" you could rip out the entire 3DS motherboard and design a new one from scratch! If your options are more limited than that, then kindly restrict your definition of "possible".

 

[Zi0v4_]

Everything is theoretically possible! It's "possible" you could rip out the entire 3DS motherboard and design a new one from scratch! If your options are more limited than that, then kindly restrict your definition of "possible".

Would it be less painful if I do it on a N3DSXL ?

 

[kijetesantakalu042]

Would it be less painful if I do it on a N3DSXL ?

New 3ds XL is designed in a modular way. The SD card reader happens to be it's own module.

You could build a board with a ribbon cable and a ribbon connector, plug the reader into it, and then plug it into the console. You could then put the SD card control logic on that board.

You could also develop it with the sd card reader disconnected from the 3ds to make sure you can get usb writing working before putting it in your 3DS.

Spoiler: images