some are HC-05 (slave only) or HC-06 (Master/slave switchable).
The HC05 can be master or slave as you know..
What can be made of this?More to the point, how tell which is which?
But my problem is that I see cheap ($6ish) BT modules on ebay, but can't seem to find anything from a repeatable online vendor like Digikey or Farnell for anything near that price range. Ebay's great for one-offs, but if I ever have to build 200 of something, I'd like to avoid it.
As to telling them apart, AFAIK they are the same hardware, it's just the firmware that determines there modus operandi
The connections to the backplane are different but I think you only find out about that when you've got it wrong.