28.3.4 Sleep Mode Operation

CTCSCAN is halted in all sleep modes. In all CPU Sleep modes, the CRCSCAN peripheral is halted and will resume operation when the CPU wakes up.

The CRCSCAN starts operation three cycles after writing the EN bit in CRCSCAN.CTRLA. During these three cycles, it is possible to enter Sleep mode. In this case:
  1. The CRCSCAN will not start until the CPU is woken up.
  2. Any interrupt handler will execute after CRCSCAN has finished.