I decided to use a 32 GB micro SD card with an SD adapter on my Wii U, it is already formated and I can't see it on my Wii U menu! I can see it on the Wii menu but not on the Wii U one. How does this exactly works?

Can you use SD cards as memory for the Wii U?  I thought you could only use the USBs and th SD card slot is to transfer and store Wii data.

http://www.nintendo.com/consumer/systems/wiiu/en_na/system_sd_cards.jsp

If so I didn't know... So I can only expand the memory by using a USB drive?

Don't take my word for it, the guy that posted after me had a link that looks like it proves me wrong.

But is the SD supposed to act as memory for the Wii U?  That isn't answered there

Maybe this will help, I didn't read it in detail or anything

http://www.gamefaqs.com/boards/631516-wii-u/65965407?page=2

No idea, I haven't tried it. I was just trying to help. I would use your sd for your 3DS if you have one and get yourself an external HD for the Wii U.

Okay we can close this thread! It seems the SD card can't be used to expand the Wii U storage capacity...

http://arstechnica.com/gaming/2012/11/why-the-8gb-wii-u-can-only-store-3gb-of-downloaded-games-and-dlc/

Here at the end, it explains it quite nicely.

Thanks for the help thoug! It seems I'll have to use and external HD .