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4.12
Dual Staged Watchdog Timer
Basics
A watchdog timer (or computer operating properly (COP) timer) is a computer hardware or software timer that triggers a
system reset or other corrective action if the main program, due to some fault condition, such as a hang, neglects to
regularly service the watchdog (writing a „service pulse" to it, also referred to as „kicking the dog", "petting the dog",
„feeding the watchdog" or „triggering the watchdog"). The intention is to bring the system back from the nonresponsive
state into normal operation.
The microETXexpress®-DC offers a watchdog which works with two stages that can be programmed independently and
used one by one.
Available Events
Reset:
A reset will restart the module and starts POST and operating system new.
NMI:
A non-maskable interrupt (NMI) is a computer processor interrupt that cannot be ignored by standard interrupt masking techniques in the system. It is typically
used to signal attention for non-recoverable hardware errors.
Delay:
Might be necessary when an operating system must be started and the time for the first trigger pulse must extended. (Only available in the first stage)
Cascade:
Does nothing, but enables the 2nd stage after the entered time-out.
WDT Signal
B27 on COM Express® Connector offers a signal that can be asserted when a watchdog timer has not been triggered within
time. It can be configured to any of the 2 stages. Deassertion of the signal is automatically done after reset. If
deassertion during runtime is necessary please ask your Kontron technical support for further help.
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