Hi Juergen,
I've been trying to connect, but finally I gave up.
Just for your clarity, what I've been doing is:
1. Mini is the slave, the other BT device (connectBlue) is configured as SPP master.
2. Mini is configured with AIRcable.bas which is a sample "Micro Slave" download
from wiki below:
(I added LED control to show connection status)
3. Power both them up.
4. Initiate pairing from connectBlue. Enter PIN and paired and connected successfully.
5. While both devices are being connected, turn OFF connectBlue, then it's of course
disconnected. At this moment, mini is kept powered.
6. Turn ON connectBlue. connectBlue attempts connection automatically and it
successfully connects.
7. Repeat 5 and 6 many times, all successful.
8. Turn OFF mini. connectBlue is kept powered. Connection lost, of course.
9. Turn ON mini. connectBlue attempts connection, but failed.
I hope mini is connected in the case 9 above. I tried this sequence many times
tinkering, but failed.
I tried with other several units of mini, but the result was the same.
I actually have an Android App which is an SPP utility, and the result was
exactly the same. To re-connect after power OFF of mini, I needed to re-pair.
As you say, mini is seemingly rejecting a connection from its counterpart which
was once connected. And from my point of view, mini is doing so because it forgets
pairing information (link key as you say) after power OFF.
Now I'm very interested in what you mentioned as simple secure pairing. Do you
think that will help me?
Regards,
Ryuji