After some Googling and studies, finally I can pair my ProMini with raspi. It seems the shift key is not working, don’t know what’s wrong. But while it works normally with my Mac and PC, I moved to the next step and stucked there — auto connection.
Seems the bluez library isn’t well documented in this, or it just leaving this for developers. If it is the case then I’ll have to write my own service for detecting the keyboard. (awe… headache)
Google suggest bluetooth over linux CLI is kinda poorly supported, developed and documented… well let’s keep studying.