FabiaTech FB2402, User Manual

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FabiaTech Corporation
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Watchdog Timer
This section describes how to use the Watchdog Timer 0 and Watchdog Timer 1,
including disabled, enabled, and triggers functions.
The FB2402 is equipped with a programmable time-out period watchdog timer.
User can use the program to enable the watchdog timer. Once you have enabled
the watchdog timer, the program should trigger it every time before it times out. If
your program fails to trigger or disable this timer before it times out because of
system hang-up, it will generate a reset signal to reset the system or trigger an IRQ
signal. The time-out period can be programmed to be 30.5 μ seconds to 512
seconds.
Watchdog Timer Setting
The watchdog timer (WDT0 and WDT1) is a circuit that may be used from your
program software to detect crashes or hang-ups. 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 zero and start to count again. If your program fails to trigger
the watchdog timer before time-out, it will generate a reset pulse to reset the
system or trigger an IRQ signal and NMI to tell your program that the watchdog is
times out. To access WDT0 registers the software programmer use the index port
22hh data port 23h and access WDT1 registers, its use IO ports A8h ~ AEh.