ATXMEGA384C3_14 Datasheet, PDF (25/125 Pages) ATMEL Corporation – 8/16-bit Atmel XMEGA C3 Microcontroller

13. WDT – Watchdog Timer
13.1
Features
• Issues a device reset if the timer is not reset before its timeout period
• Asynchronous operation from dedicated oscillator
• 1kHz output of the 32kHz ultra low power oscillator
• 11 selectable timeout periods, from 8ms to 8s
• Two operation modes:
– Normal mode
– Window mode
• Configuration lock to prevent unwanted changes
13.2
Overview
The watchdog timer (WDT) is a system function for monitoring correct program operation. It makes it possible to recover
from error situations such as runaway or deadlocked code. The WDT is a timer, configured to a predefined timeout
period, and is constantly running when enabled. If the WDT is not reset within the timeout period, it will issue a
microcontroller reset. The WDT is reset by executing the WDR (watchdog timer reset) instruction from the application
code.
The window mode makes it possible to define a time slot or window inside the total timeout period during which WDT
must be reset. If the WDT is reset outside this window, either too early or too late, a system reset will be issued.
Compared to the normal mode, this can also catch situations where a code error causes constant WDR execution.
The WDT will run in active mode and all sleep modes, if enabled. It is asynchronous, runs from a CPU-independent clock
source, and will continue to operate to issue a system reset even if the main clocks fail.
The configuration change protection mechanism ensures that the WDT settings cannot be changed by accident. For
increased safety, a fuse for locking the WDT settings is also available.
XMEGA C3 [DATASHEET]
25
Atmel-8361F-AVR-ATxmega384C3-Datasheet–11/2014