Watch-Dog Timer - Boser HS-3200/4M Manual

2.7Watch-Dog Timer

The Watch-Dog Timer is enabled by reading the port 443H. It should be
triggered before the time-out period ends; otherwise, it will assume that the
program operation is abnormal and will either issue a reset signal to start
again or activate a NMI to the CPU. The Watch-Dog Timer is disabled by
reading the port 043H.
JP9 determines the Watch-Dog timer function. It can disable the Watch-Dog
timer or connect the Watch-Dog timer to the reset trigger or NMI trigger.
JP9 : Watch-Dog Active Select
??
JP9
*1-2
2-3
OPEN
*) : default setting
JP14 : WDT Time - Out Period
??
PERIOD
*1 sec
2 sec
10 sec
20 sec
110 sec
220 sec
*) : default setting
When the power of the HS-3200/4M is turned on, the Watch-Dog timer is
disabled. The watch-dog timer can be enabled by reading the Watch-dog timer
enable/refresh control port (443H) and disabled by reading the Watch-dog
timer disable control port (43H). After the Watch-dog timer is enabled, the
user must constantly refresh the Watch-dog timer by reading the Watch-dog
timer enable/refresh port (443H) every 1, 2, 10, 20, 110 or 220 seconds. If the
user fails to do so or the system hangs, the watch-dog
timer will automatically reset the system or issue a NMI(Non-maskable
interrupt).
The Watch-Dog Timer is controlled by two I/O ports.
Disabled Watch-Dog Timer
1-2 3-4
OFF OFF
OFF OFF
OFF ON
OFF ON
ON OFF
ON OFF
DESCRIPTION
System Reset
Active NMI
5-6
ON
ON
OFF
OFF
OFF
OFF
7-8
OFF
ON
OFF
ON
OFF
ON
15