I have four bluetooth modules, two are HC-05, and the other 06(which ones were which, I dont remember), which I took the time to test and see how they work and how far they can go before cutting out.
The far wall of my bedroom to my front door is 37.2ft, in which I wanted to know how far I could be and still have them pair up. I found out that they can still find each other, pair up at 34 - 36 ft, but given my house is mesh lined, I thought the number would vary. Turns out, not by much. I tested the paring range again outside and roughly at 40ft they could just barely pair up. (They would pair up for a few seconds then lose connection)
As I said, yes they can be difficult to set up if you’re doing it for the first time, but once you get a hang of it, its simple plug and play. At least with the modules I have. They are all currently set to the default setting, 9600, no parity bit…etc. Yet, I can throw together a simple Serial sketch to send one char from one arduino to the other and see it on the serial monitor.
A V1.2 will not pair with a V1.02 nor to a V1.05, but two V1.05 will. So technically I only have one working pair, but I can still use the other slave, (V1.2) to debug to my computer if needed.
These are the only modules I own, so the same can’t be said with confidence for the blue, Silver or GoldSmirf. Their protocol may be completely different or they could be the same, but if I don’t have them, then I can’t test them.
I tried to resize the image as best I could without losing quality.
Added: the two on the left do automaticly pair to one another, but the other two, since they are not the same version, I can’t be certain. I do know that all four need to be manually paired when connecting to my laptop.