We at the blog love to demonstrate new, cutting edge features and documenting them for current and future users of the emulator. Wii USB device emulation is one of those things that lacks data and testing in Dolphin. It requires real hardware just to try it out and only a select few people are crazy enough to work on anything involving the Wii IOS HLE. The first time E-ticket Service Launch support was added to Dolphin, it managed to break connecting Wiimotes; that's just how touchy that code can be!
When looking around, the most common answer is that USB Devices won't work with Dolphin, with examples of the Konami microphones being given and recommendations toward an old branch that implemented Wii Speak support (which still doesn't support those microphones.) For anyone searching, the answer to "Do Wii USB devices work in Dolphin?" came up as a flat no on the wiki, issue tracker, and forums.
It turns out that a lot of these devices work perfectly in Dolphin! Support was added way back in 2013, but seems to have been mostly forgotten by time. The primary reason for this was that it was a part of the Wii Networking merge. The main focus of that merge was to add Wifi support to Dolphin for playing games on the still active Nintendo servers. Hidden within that was an USB HID implementation for Dolphin. Somehow, this wasn't really tested or noted for the most part and snuck into the emulator almost unnoticed. When a discussion about this came up on IRC a few days ago, we just had to try and see what would happen when we plugged some Wii accessories into our computers for Dolphin.
The current status is that all Skylanders Portals for Wii, EA Active's Heart/Motion Monitor Dongle, Wii Wireless Steering Wheel, possibly the Rockband Instruments and Tony Hawk Ride Skateboard work over Dolphin's USB HID Support. Any device that uses the Wii's support for USB HID should work in Dolphin. The caveat is that many accessories don't use this interface. We currently know that games that use USB Microphones (Just Dance, Sing It, Boogie, etc.) will not detect them in Dolphin. As well, the Your Shape camera also does not work. More obscurely, USB Harddrives/Mass Storage do not work either (as used by Dragon Quest X).
Do note that this feature requires real hardware. Users cannot use Dolphin to "emulate" a portal and figurines; it is merely interacting with the real devices as if it were a Wii.
Setting up for USB HID¶
There is a little bit of setup to actually use these accessorites though. Users familiar with setting up Nintendo's GameCube Controller Adapter for Dolphin will be fairly familiar with what needs to be done. Our computers need to know to use the WinUSB/LIBUSB drivers for the devices. The instructions are identical to the Adapter guide, except you must select whichever device you're planning to use with Dolphin. For the Skylanders Portals, it's "Spyro Porta", for EA Active, all devices are marked with "EA Active". After doing this, the device will work in Dolphin just fine whenever plugged in. Do note, this driver only affects your computer, the accessory itself is unchanged and will still work on console just fine.