I'm setting up a mobile application to support bluetooth communication between an android phone and one dual-mode bluetooth module. Two devices must init a BLE connection and transfer sound through HandsFree profile. At any time, two device must be able to re-establish these communications.
Should application shut down the Classic bluetooth process after sound transferring is done and always connect by BLE??
If I understood your question correctly, you don't need Bluetooth Low Energy (BLE) for your application. If you just want to transfer sound through the HandsFree profile, then this can be accomplished with classic Bluetooth alone and you can even turn BLE for the entirety of the application.
Please see this Android Developer page which gives a step-by-step guide on how to do this and provide sample code:-
https://developer.android.com/guide/topics/connectivity/bluetooth#Profiles
Finally, please note that for the most part BLE and classic Bluetooth are mutually exclusive; even though they are part of the same specification, they are like two different wireless technologies and in almost all cases your application will need one or the other, but not both. Please see this post for more details:-
Can a Bluetooth LE powered device discover a classic Bluetooth device and vice-versa?
I hope this helps.
