1.40.18 Reset Controller (RSTC)

The Reset Controller collects the various reset sources and generates reset for the device and allows the reset source to be identified by the software.

  • Power On Reset: The device contains a poweronreset (POR) detector, which keeps the system reset until power is stable. This eliminates the need for external reset circuitry to guarantee stable operation when powering up the device.

  • VDDCORE Brown Out Reset: BOD12 will reset the device if a voltage of 1.2 V or below is observed on the I/O pin supplying power to the MCU core (VDDCORE).

  • VDDANA Brown Out Reset: BOD33 resets the device if the voltage on the VDDANA pin falls below a value configured by the SYSCTRL

  • Watchdog Reset: The watchdog reset occurs when it times out

  • System Reset: The System Reset Request is a software reset generated by the CPU when asserting the SYSRESETREQ bit located in the Reset Control register of the CPU

  • External Reset: A external reset is generated when a low level is detected on the RESET pin

Resets are divided into two modes based upon the source of the reset.

  • Power Resets include resets generated by POR, BOD12, and BOD33.

  • User Resets consist of the external reset, WDT, and the software reset instruction

Both power and user reset causes the device to restart and set most registers of the MCU to a preset state. The difference between the two modes is how they affect the Real Time Clock, the 32 K oscillator, and the WDT. The underlying reasoning for having two reset modes is to protect the operation of the WDT and the RTC from nonpower related anomalies.

Using The Library

The reset controller (RSTC) peripheral library provides API to find the cause of last device reset

Library Interface

Reset Controller peripheral library provides the following interfaces:

Functions

Name Description
RSTC_ResetCauseGet Reports the cause of the last reset
RSTC_BackupExitCauseGet Reports the cause of the Backup Exit

Data types and constants

Name Type Description
RSTC_RESET_CAUSE Typedef Identifies the type of reset
RSTC_BKUPEXIT_CAUSE Typedef Identifies the cause for Backup reset