Intel HS-2601A 443H, 443H, 045H

After an Enable cycle of WDT, user must immediately execute a Refresh cycle to WDT before its period setting comes to an end every 1, 2, 10, 20, 110 or 220 seconds. If the Refresh cycle does not activate before WDT period cycle, the onboard WDT architecture will issue a Reset or NMI cycle to the system. There are three I/O ports that control the Watchdog Timer.

443H	I/O Read	The Enable cycle
443H	I/O Read	The Refresh cycle
045H	I/O Read	The Disable cycle

The following sample program shows how to Enable, Disable and Refresh the Watchdog Timer：

WDT_EN_RF	EQU	0433H
WDT_DIS	EQU	0045H
WT_Enable	PUSH	AX	; keep AX DX
	PUSH	DX
	MOV	DX,WDT_EN_RF	; enable the WDT
	IN	AL,DX
	POP	DX	; get back AX, DX
	POP	AX
	RET
WT_Refresh	PUSH	AX	; keep AX, DX
	PUSH	DX
	MOV	DX,WDT_ET_RF	; refresh the WDT
	IN	AL,DX
	POP	DX	; get back AX, DX
	POP	AX
	RET
WT_DISABLE	PUSH	AX
	PUSH	DX
	MOV	DX,WDT_DIS	; disable the WDT
	IN	AL,DX
	POP	DX	; get back AX, DX
	POP	AX
	RET

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