16.4.2.2 Reset Causes and Effects

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

These are the types of Reset sources:

  • Power supply Reset: Resets caused by an electrical issue. It covers POR and BOD Resets.
  • User Reset: Resets caused by the application. It covers external Resets, system Reset requests, and Watchdog Resets (WDR).

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

Table 16-1. Effects of the Different Reset Causes
Power Supply ResetUser Reset
POR, BODVDDExternal ResetWDT Reset, System Reset Request
RTC, OSC32KCTRL, RSTCReset--
GCLK with WRTLOCKReset--
Debug logicResetReset-
OthersResetResetReset

An external Reset is generated when the RESET pin is pulled low.

The POR and BODVDD Reset sources are generated by their corresponding modules in the Supply Controller Interface (SUPC). Refer to the Supply Controller section for more information.

The Watchdog Timer (WDT) Reset is generated by the Watchdog Timer. Refer to the Watchdog Timer section for more information.

The System Reset Request is a Reset generated by the CPU when the SYSRESETREQ bit ,located in the Reset Control register of the CPU, is asserted. Refer to the Arm® Cortex® Technical Reference Manual on http://www.arm.com for more information.

The CPU Lockup Reset Request is a Reset generated when the CPU enters the architecturally defined LOCKUP state. Refer to the Arm® Cortex® Technical Reference Manual on http://www.arm.com for more information.

Note: Refer to the TRST Specification in the Power Supply section of the Electrical Characteristics section for more information.