NOTES:
1. If the same level is not detected on enabled pin three or four times in a row at
the sampling clock, the signal is eliminated as noise.
2. A pulse level should be input for the duration of 3 clock or more to be actually
detected as a valid edge.
3. The port de-bounce is automatically disabled at stop mode and recovered after
stop mode release.
4. Refer to Port De-bounce Selection Register (PSR0) for the de-bounce time.