Generally following equation is applies:
You must know scale of frequency. Scale * Q.15.
For example scale = 1000 Hz, if Q1.15 = 0.4, then frequency is 1000*0.4 = 400 Hz
I hope this helps.
It would be helpful if you could provide us more information, which MCU are you using? Are you running a demo project?
Thanks in advance!
Technical Support Engineer