MPU-6050 gyro calibration

Chagrin:
The MPU-6050 has a +/- 20 degrees/second tolerance for zero rate, but this is normal for any gyro chip.

You should be using the accelerometer readings in combination with the gyro for a zero point of reference.

thank you.
the internal DMP of this chip should already combine gyro and accell, or i'm i wrong?
i've made some screenshot of the behavior 16.50 / 19.20 / 20.50 time (chip is in the same position, i've not moved it)

Cattura_16.50.JPG

Cattura_19.20.JPG

Cattura_20.50.JPG