Reset Causes and Effects

The latest Reset cause is available in RCAUSE register, and can be read during the application boot sequence in order to determine proper action.

These are the groups of Reset sources:

Power supply Reset: Resets caused by an electrical issue. It covers POR and BODs Resets
User Reset: Resets caused by the application. It covers external Resets, system Reset requests and watchdog Resets

The following table lists the parts of the device that are reset, depending on the Reset type.

Table 1. Effects of the Different Reset Causes
	Power Supply Reset		User Reset		Backup Reset
	POR, BODVDD	BODCORE	External Reset	WDT Reset, System Reset Request	RTC, BBPS
RTC, OSC32KCTRL, RSTC, CTRLA.IORET bit of PM	Y	N	N	N	N
GCLK with WRTLOCK	Y	Y	N	N	Y
Debug logic	Y	Y	Y	N	Y
Others	Y	Y	Y	Y	N

The external Reset is generated when pulling the RESET pin low.

The POR, BODCORE, and BODVDD Reset sources are generated by their corresponding module in the Supply Controller Interface (SUPC).

The WDT Reset is generated by the Watchdog Timer.

The System Reset Request is a Reset generated by the CPU when asserting the SYSRESETREQ bit located in the Reset Control register of the CPU (for details refer to the ARM^® Cortex™ Technical Reference Manual on http://www.arm.com).