Boser HS-6237, Руководство пользователя

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23
JP7
:
Watchdog Timer Active Type Setting
Options Settings
Active NMI Short 1-2
System Reset (default) Short 2-3
Disabled Watchdog Timer Open
JP9 (5-10): WDT Timeout Period Select
Period PINS 5-6 PINS 7-8 PINS 9-10
1 sec (default) Short Short Short
2 sec Open Short Short
10 sec Short Open Short
20 sec Open Open Short
110 sec Short Short Open
220 sec Open Short Open
The Watchdog Timer is disabled after the system Power-On. It can be
enabled via an Enable cycle and reading the control port (443H), or via
a Refresh cycle and reading the control port (443H), or via a Disable
cycle and reading the disable control port (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