Advantech ASMB-820-00A1E, User Manual

Page: 74 / 88

ASMB-820I User Manual 64
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
;-----------------------------------------------------------
Table A.1: Watchdog Timer Registers
Address of
register (2E) Read/
Write
Value (2F) & description
87 (hex) -
Write this address to I/O address port 2E (hex) twice to unlock the
NCT6776F
07 (hex) write Write 08 (hex) to select register of watchdog timer.
30 (hex) write
Write 01 (hex) to enable the function of the watchdog timer. Dis-
abled is set as default.
F5 (hex) write
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.
F6 (hex) write
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.
F7 (hex)
read/
write
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”.
AA (hex) - Write this address to I/O port 2E (hex) to lock NCT6776F.