29.3.3.1 Normal Mode

A single time-out interval is configured for the WDT in the Normal mode operation. If the WDT is not reset from the software using the WDR instruction during the configured time-out interval, the WDT will issue a system reset.

Each time the WDT is reset by software using the WDR instruction, a new WDT time-out interval starts.

There are 11 possible WDT time-out intervals (TO_WDT), selectable from 244 μs to 250 ms by writing to the Period (PERIOD) bit field in the Control A (CTRLA) register.

The figure below shows a typical timing scheme for the WDT operating in Normal mode.

Figure 29-2. Normal Mode Operation

The Normal mode is enabled as long as the Window (WINDOW) bit field in the CTRLA register is ‘0x0’.