40.6.8 Synchronization

Due to asynchronicity between the main clock domain and the peripheral clock domains, some registers need to be synchronized when written or read.

The following bits are synchronized when written:

• Software Reset and Enable bits in Control A register (CTRLA.SWRST and CTRLA.ENABLE)
• Capture Channel Buffer Valid bit in STATUS register (STATUS.CCBUFVx)

The following registers are synchronized when written:

• Control B Clear and Control B Set registers (CTRLBCLR and CTRLBSET)
• Count Value register (COUNT)
• Period Value and Period Buffer Value registers (PER and PERBUF)
• Channel x Compare/Capture Value and Channel x Compare/Capture Buffer Value registers (CCx and CCBUFx)

The following registers are synchronized when read:

• Count Value register (COUNT): Synchronization is done on demand through READSYNC command (CTRLBSET.CMD).

Required write synchronization is denoted by the Write-Synchronized property in the register description.

Required read synchronization is denoted by the Read-Synchronized property in the register description.