39.6.10 Synchronization
Due to the asynchronicity between the main clock domain (CLK_CAN_APB) and the peripheral clock domain (GCLK_CAN) some registers are synchronized when written. When a write-synchronized register is written, the read back value will not be updated until the register has completed synchronization.
The following bits and registers are write-synchronized:
INIT Initialization bit in CC Control register (CCCR.INIT)