19.3.3.1 Normal Mode
In Normal mode operation, a single time-out period is set
for the WDT. If the WDT is not reset from software using the
WDR any time before the time-out occurs, the WDT
will issue a system Reset.
A new WDT time-out period will be started each time the WDT is reset by
WDR.
There are 11 possible WDT time-out periods (TOWDT), selectable from 8 ms to 8s by writing to the Period (PERIOD) bit field in the Control A (WDT.CTRLA) register.
Normal mode is enabled as long as the WINDOW
bit field in the Control A (WDT.CTRLA) register is 0x0.