Nagasaki PC104-688VL, User Manual

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NAGASAKI IPC
48
Watchdog Timer Setting
The watchdog timer is a circuit that may be used from your program software to
detect system crashes or hang-ups. LED1 on this CPU board is the watchdog timer
indicator, which is located at the upper-left corner above the USB connector.
Whenever the watchdog timer is enabled, the LED will blink to indicate that the timer is
counting. The watchdog timer is automatically disabled after reset.
Once you have enabled the watchdog timer, your program must trigger the
watchdog timer every time before it times out. After you trigger the watchdog timer, it
will be set to non-zero value to watchdog counter and start to count down again. If
your program fails to trigger the watchdog timer before time-out, it will generate a
reset pulse to reset the system.
The factor of the watchdog timer time-out constant is approximately 1 second. The
period for the watchdog timer time-out period is between 1 to 256 timer factors.
If you want to reset your system when watchdog times out, the following table listed
the relation of timer factors between time-out periods.
Watchdog Timer Enabled
Watchdog Timer Trigger
Watchdog Timer Disabled
Reset
Time Factor
Time-Out Period
Sec/Minutes
01h 1
02h 2
03h 3
04h 4
05h 5
06h 6
~ ~
FFh 256
Note: In the DRIVER/WatchDog/F75101r directory a demo file is included to provide
watchdog control information and assemble source code.