@doantrungnghia05
I'm pretty sure the boards which only got a gyro on them don't even convert the gyro readings into degrees, but uses the rate as the input to there PID loop.
You can find plenty of firmware for you board. There is no need to write your own. For instance I found this using Google: GitHub - DaneGardner/KKMulticontroller: kkmulticopter flight controller software
You should ask at a quadrocopter forum or something like that instead.