After the reset of the supervisor is released, the lower boundary of the first WDI window is disabled. However, after the first WDI pulse low-to-high transition is detected, the lower boundary function of the window is enabled. All further WDI pulses must fit into the configured window frame.

The lower boundary of the watchdog window begins with the rising edge of the WDI trigger pulse. At the same time, all internal timers are reset. If an external capacitor is used, the lower boundary is impacted because of the different oscillator frequency. See the Section 8.2.2.1 section for additional details. Figure 7-3, especially the shaded boundary area, was prepared in a nonreal ratio scale to better visualize the description.

Figure 7-3 Timing Diagram