FabiaTech FX5612, Руководство пользователя

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FabiaTech Corporation
44
Watchdog Timer Enabled
To enable the watchdog timer, you have to output a byte of timer factor to the
watchdog register whose address is 2Eh and data port is 2fH. The following is an
Assemble program, which demonstrates how to enable the watchdog timer and set
the time-out period at 28 seconds.
;------------------------------------------------------------------------------------------
; Enter the extended function mode, interruptible double-write
;------------------------------------------------------------------------------------------
Mov dx, 2eh ; Enter to extended function mode
Mov al, 87h
Out dx,al
Out dx,al
Mov al,07h
Out dx,al
;------------------------------------------------------------------------------------------------------
; Logical device 8, configuration register CRF5 Bit 3,CRF6 Bit 0~7
;------------------------------------------------------------------------------------------------------
Mov dx,2fh
Mov al,08h ; Select Logical Device 8 of watchdog tim
er
Out dx,al
Mov dX,2eh
Mov al,0f5h ;Set second as counting unit
Out dx,al
Mov dx,2fh
In al,dx
Or al,c0 ; Trigger P/W LED.
And al,not c8h ;Set Second.
;And al,c8h ;Set Minute.
Out dx,al
Mov dx,2eh
Mov al,0f6h
Out dx,al
Mov dx,2fh
Mov al,28h ; Set timeout interval as 28seconds and start counting
Out dx,al
;------------------------------------------
; Exit extended function mode
;------------------------------------------
Mov dx,2eh
Mov al,0aah
Out dx,al
Watchdog Timer Trigger
After you enable the watchdog timer, your program must write the same factor as
enabling to the watchdog register at least once every time-out period to its previous
setting. You can change the time-out period by writing another timer factor to the
watchdog register at any time, and you must trigger the watchdog before the new
time-out period in next trigger.