Table A.1: Watchdog Timer Registers; A.2.1 Example Programs - Advantech AIMB-781 User Manual

Table A.1: Watchdog timer registers

Address of Read/
register (2E) Write
87 (hex) -
07 (hex) write
30 (hex) write
F5 (hex) write
F6 (hex) write
read/
F7 (hex)
write
AA (hex) -
A.2.1 Example Programs
Enable watchdog timer and set 10 seconds as the timeout interval
;-----------------------------------------------------------
Mov dx,2eh ; Unlock NCT6776F
Mov al,87h
Out dx,al
Out dx,al
;-----------------------------------------------------------
Mov al,07h ; Select registers of watchdog timer
Out dx,al
Inc dx
in al,dx
Or al,08h
Out dx,al
;-----------------------------------------------------------
Dec dx; Enable the function of watchdog timer
Mov al,30h
Out dx,al
Inc dx
Mov al,01h
Out dx,al
;-----------------------------------------------------------
AIMB-781 User Manual
Value (2F) & description
Write this address to I/O address port 2E (hex) twice to unlock the
NCT6776F
Write 08 (hex) to select register of watchdog timer.
Write 01 (hex) to enable the function of the watchdog timer. Dis-
abled is set as default.
Set seconds or minutes as units for the timer. Write 0 to bit 3: set
seconds as counting unit. [default]. Write 1 to bit 3: set minutes as
counting unit.
Write 1 to bit 4: Watchdog timer count mode is 1000 times faster.
If bit 3 is 0, the count mode is 1/1000 seconds mode. If bit 3 is 1, the
count mode is 1/1000 minutes mode.
0: stop timer [default]
01 ~ FF (hex): The amount of the count, in seconds or minutes,
depends on the value set in register F5 (hex). This number decides
how long the watchdog timer waits for strobe before generating an
interrupt or reset signal. Writing a new value to this register can
reset the timer to count with the new value.
Bit 6: Write 1 to enable keyboard to reset the timer, 0 to dis-
able.[default]
Bit 5: Write 1 to generate a timeout signal immediately and auto-
matically return to 0. [default=0]
Bit 4: Read status of watchdog timer, 1 means timer is "timeout".
Write this address to I/O port 2E (hex) to lock NCT6776F.
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