Dual Staged Watchdog Timer - Kontron COMe-mTT10 User Manual

4.14

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 COMe-mTT10 offers a watchdog which works with two stages that can be programmed independently and used one by
one.
Time-out 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.
SCI A system control interrupt (SCI) is a OS-visible interrupt to be handled by the OS using AML code
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)
WDT Signal only This setting triggers the WDT Pin on baseboard connector (COM Express® Pin B27) only
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.
37
COMe-mTT10 / Features and Interfaces