16.4.2.4 Watchdog Reset

The Watchdog reset is entered when a watchdog fault occurs. This reset lasts three MD_SLCK cycles.

When in Watchdog reset, the Processor reset and the Peripheral reset are asserted. The NRST_OUT line is also asserted, depending on the value of RSTC_MR.ERSTL. However, the resulting low level on NRST_OUT does not result in a User reset state.

The WDT is reset by the Processor reset signal. As the watchdog fault always causes a Processor reset if WDT_MR.WDRSTEN is written to ‘1’, the WDT is always reset after a Watchdog reset, and the Watchdog is enabled by default and with a period set to a maximum.

When WDT_MR.WDRSTEN is written to ‘0’, the watchdog fault has no impact on the RSTC.

After a watchdog overflow occurs, the report on the RSTC_SR.RSTTYP may differ (either WDT_RST or USER_RST) depending on the external components driving the NRST pin. For example, if the NRST line is driven through a resistor and a capacitor (NRST pin debouncer), the reported value is USER_RST if the low-to-high transition is greater than one MD_SLCK cycle.