Hi http://doc.qt.io/qt-5/qtbluetooth-index.html Do you have BlueZ 4.x/5.x installed ?

No, because they were neved emitted. I just found this: https://bugreports.qt.io/browse/QTBUG-38401, it seems that they are not implemented yet for Bluez 5. However, I would like to set the pin in only one-way, the raspberry shouldn't accept any pairing if the pin code (probably hardcoded in the raspberry) is different from the one entered by the user. Anyway, I'm not sure if this is possible.

@raven-worx no, sorry, as said in the last post it doens't listen for incoming pairing request. Is the application which has to issue a pairing request! It's quite different. Of course the final result is pretty the same, but I didn't understand how it works from the documentation.

Hi and welcome to devnet, If possible, you should upgrade to 5.5, IIRC, there's been a lot of work done in the bluetooth module for it.