Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Fiche De Données

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Atmel | SMART SAM D21 [DATASHEET]

Atmel-42181C–SAM-D21_Datasheet–07/2014

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 configured to a predefined time-out period, and is 
constantly running when enabled. If the WDT is not cleared within the time-out period, it will issue a system reset. An 
early-warning interrupt is available to indicate an upcoming watchdog time-out condition.

The window mode makes it possible to define a time slot (or window) inside the total time-out period during which the 
WDT must be cleared. If the WDT is cleared 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 the WDT to be cleared 
frequently.

When enabled, the WDT will run in active mode and all sleep modes. It is asynchronous and runs from a CPU-
independent clock source.The WDT will continue operation and issue a system reset or interrupt even if the main clocks 
fail.

z

Issues a system reset if the Watchdog Timer is not cleared before its time-out period

z

Early Warning interrupt generation

z

Asynchronous operation from dedicated oscillator

z

Two types of operation:

z

Normal mode

z

Window mode

z

Selectable time-out periods, from 8 cycles to 16,000 cycles in normal mode or 16 cycles to 32,000 cycles in window 
mode

z

Always-on capability

GCLK_WDT

COUNT

Reset

PER/WINDOW/EWOFFSET

0

CLEAR

0xA5

Early Warning Interrupt