# Normal Mode

In the Normal mode operation, a single time-out period is set for the WDT. If the WDT is not reset from software using the WDR instruction during the defined time-out period, the WDT will issue a system Reset.

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

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.

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

Figure 1. Normal Mode Operation

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