Casio QT-7300 Series, Руководство по обслуживанию

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4-15. Watchdog Function
The QT-7300 features a system protective device, watchdog timer which can generate a CPU reset when the
system comes to a halt or failure. This function is to ensure the system's reliability during unattended operation.
The trigger sources for the watchdog contain both temperature over range and system failure. The system failure
may be caused by thunder, power glitch, radio interference, software bug or whatever reason.
To activate the watchdog timer, some program code similar to the following code has to be written to the system
running loops:
:
Loop: read (0x121) ; enable and trigger WDT
: ; interval time between triggers
if (END) GOTO END ; must be smaller than time-out
GOTO Loop ; period
END:
read (0x120) ; disable WDT
:
The time-out period ranges from 0.5 to 1000 seconds. If special settings for temperature or time-out are needed,
please refer to the utility diskette.
4-15-1. How to Use Watchdog Function
The user can read I/O Port 121H to enable Watchdog or disable it by reading I/O Port 120H.
Reset Watchdog - Read I/O Port 121H
Time_A - Read I/O Port 121H
Time_B - Read I/O Port 121H
Disable Watchdog - Read I/O Port 120H
** Time_B_Time_A < Time_Out Setting **
In system Run_Time, you must still have to read I/O Port 121H to reset the Watchdog timer.
If the system fails, the TSR should be stopped and Watchdog reset action will be activated.