16.3.7 Synchronization Delay
The synchronization will delay write and read accesses by a certain amount. This delay D is within the range of:
5×PGCLK + 2×PAPB < D < 6×PGCLK + 3×PAPB
Where PGCLK is the period of the generic clock and PAPB is the period of the peripheral bus clock. A normal peripheral bus register access duration is 2×PAPB.