Advantech AIMB-221 manual Example Programs, Table A.1 Watchdog timer registers

Table A.1: Watchdog timer registers

Address of	Read/Write	Value (2F) & description
register (2E)
87 (hex)	-----	Write this address to I/O address port 2E (hex) twice to
		unlock the W83627HF
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. Disabled 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.
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
		disable.[default]
		Bit 5: Write 1 to generate a timeout signal immediately
		and automatically 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 the watch-
		dog timer 2.

A.3.1 Example Programs

Enable watchdog timer and set 10 seconds as the timeout interval

;-----------------------------------------------------------
Mov dx,2eh		; Unlock W83627HF
Mov al,87h
Out dx,al
Out dx,al
;-----------------------------------------------------------
Mov al,07h		; Select registers of watchdog timer
Out	dx,al
Inc	dx
Mov	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-221 User Manual 92