28.3.4 Sleep Mode Operation

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

The CRCSCAN starts operation three cycles after writing the Enable (ENABLE) bit in the Control A (CRCSCAN.CTRLA) register. 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.