The counter clock CLK_WDT_OSC is asynchronous to the bus clock (CLK_WDT_APB). Due to this
asynchronicity, writing to certain registers will require synchronization between the clock domains. Refer
to
Related Links
on page 145
OSC32KCTRL – 32KHz Oscillators Controller
on page 258
on page 1147
24.5.4. DMA
Not applicable.
24.5.5. Interrupts
The interrupt request line is connected to the interrupt controller. Using the WDT interrupt(s) requires the
interrupt controller to be configured first.
Related Links
Nested Vector Interrupt Controller
on page 44
on page 44
24.5.6. Events
Not applicable.
24.5.7. Debug Operation
When the CPU is halted in debug mode the WDT will halt normal operation.
24.5.8. Register Access Protection
All registers with write-access can be write-protected optionally by the Peripheral Access Controller
(PAC), except the following registers:
•
Interrupt Flag Status and Clear (INTFLAG) register
Optional write-protection by the Peripheral Access Controller (PAC) is denoted by the "PAC Write-
Protection" property in each individual register description.
PAC write-protection does not apply to accesses through an external debugger.
24.5.9. Analog Connections
Not applicable.
24.6. Functional Description
24.6.1. Principle of Operation
The Watchdog Timer (WDT) is a system for monitoring correct program operation, making it possible to
recover from error situations such as runaway code, by issuing a Reset. When enabled, the WDT is a
constantly running timer that is configured to a predefined time-out period. Before the end of the time-out
period, the WDT should be set back, or else, a system Reset is issued.
The WDT has two modes of operation, Normal mode and Window mode. Both modes offer the option of
Early Warning interrupt generation. The description for each of the basic modes is given below. The
settings in the Control A register (CTRLA) and the Interrupt Enable register (handled by INTENCLR/
INTENSET) determine the mode of operation:
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
313