AR-B1380/AR-1380A User’ s Guide
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5.4 WATCHDOG TIMER
This section describes how to use, disable, enable, and trigger the Watchdog Timer.
AR-B1380/AR-B1380A provides two methods for the users to utilize the watchdog timer function. One is
the watchdog timer built in the chipset, which makes use of the CPU’ s registers to use the watchdog timer.
The other is the watchdog timer program programmed by Acrosser which helps you to use the watchdog
timer through the use of the IRQ11 and IRQ15.
The SSD directory in the diskette includes the watchdog timer utility files, “ WD1380.EXE,” WD6117C.EXE,”
and WD6117C.CPP.” ”WD6117C.EXE” and WD6117C.CPP” are ALI M6117C’ s built-in watchdog timer
program. “WD6117C.EXE” demonstrates how to set/enable/disable/trigger the watchdog timer.
“WD6117C” is the source file of the “WD6117C.” The other is “ WD1380.EXE” programmed by Acrosser.
You may choose either the onchip watchdog timer or Acrosser’ s program to utilize the watchdog timer.
5.4.1 Acrosser’ s Watchdog Timer Program
The AR-B1380/AR-B1380A is equipped with a programmable time-out period watchdog timer. You can use
this program to enable the watchdog timer. Once you have enabled the watchdog timer, the program
should trigger it every time before it times out. If your program fails to trigger or disable this timer before it
times out because of a system hang-up, it will generate a reset signal to reset the system. The time-out
period can be programmed to be from 3 to 42 seconds.
Watchdog
Register
Time Base
Counter
and
Compartor
Enable (D7)
Time Factor (D0-D2)
Write and Trigger
Watchdog
LED
RESET
Figure 5-1 Watchdog Block Diagram
(1) Set up the Watchdog Timer by IRQ15/IRQ11
The watchdog timer is a circuit that may be used from your program software to detect crashes or hang-ups.
Whenever the watchdog timer is enabled, the LED will blink to indicate that the timer is counting. The
watchdog timer is automatically disabled after reset.
Once you have enabled the watchdog timer, your program must trigger the watchdog timer every time
before it times-out. After you trigger the watchdog timer, it will be set to zero and start to count again. If
your program fails to trigger the watchdog timer before time-out, it will generate a reset pulse to reset the
system or trigger the IRQ15 signal to tell your program that the watchdog has timed out.
The factor of the watchdog timer time-out constant is approximately 6 seconds. The period for the
watchdog timer time-out period is between 1 to 7 timer factors. If you want to reset your system when the
watchdog times out, the following table lists the relation of timer factors between time-out period.
Summary of Contents for AR-B1380
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