I downloaded retroarch on my nvidia shield. The shield controller seems to already be mapped fine, as well as my buffalo snes controller. However I also have a buffalo famicom controller I'd like to use but I get an error that the controller is not configured, so I can't use it. If I can't use it, I can't map anything to it because I can't even navigate the menu. How do I manually get this controller configured if I can't use it at all?

By the way the controller itself works just fine for the shield, it is just retroarch that complains it isn't configured.