Just set up a folder on the root of the phones internal memory, and another "test" folder on the external SD.
Typically most phones know when they're plugged in, and automatically set themselves to sharing mode unless specified otherwise.
As long as it looks like this: Folder/Files, or Folder/Files/Folder/Files, etc. then it will work, but they HAVE to be in a main folder on an object like phones and it would probably be a good standard practice to name it "audio" or the likes just in case.
I haven't done it, but I know my 16gig drive I bought from ripoffshack for 9 bucks on clearance works just fine.
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View my fuel log 2014 Mirage ES 1.2 manual: 36.2 mpg (US) ... 15.4 km/L ... 6.5 L/100 km ... 43.5 mpg (Imp)