ADLINK Technology cPCI-6810, User Manual

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Appendix 65
Appendix B - WatchDog Timer Programming Guide
The Watchdog Timer (WDT) can monitor the system’s status.
Once a value is given to the WDT, the timer will begin to count
down. If the system becomes idle or hangs, the system will reboot
itself when the timer times out.
The Watch Dog timer includes an 8-bit timer clocked by a 1-minute
internal clock that is derived from the battery-backed 32.768KHz
crystal clock generator. The timer is loaded with the WATCHDOG
Time-Out data value written in the WDTO register and counts
down to zero. This 8-bit data enables time-out values between 1
and 255 minutes to be programmed (00h is an invalid data value).
The following events can trigger the WATCHDOG by reloading the
timer:
X
Keyboard interrupt
X
Mouse interrupt
X
Serial Port 1 interrupt
X
Serial Port 2 interrupt
X
Software writing to control register
All control registers are accessed through the following I/O ports.
I/O mapped Port
Index port Data Port
2EH 2FH