The lower boundary can be calculated based on the values listed in the Section 6.7 table. Additionally, facts must be taken into account to verify that the lower boundary is where it is expected. Because the internal oscillator of the window watchdog is running free, any rising edge at the WDI pin is taken into account at the next internal clock cycle. Accounting for any rising edge at the WDI pin occurs regardless of the external source. Because the shift between internal and external clock is not known, consider the worst-case condition when calculating this value.