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CHAPTER 11 WATCHDOG TIMER
11.5
Usage Notes on the Watchdog Timer
Notes on using the watchdog timer are given below.
■ Usage Notes on the Watchdog Timer
●
Stopping the watchdog timer
Once the watchdog timer is activated, it cannot stop until a power-on or watchdog reset occurs. The
watchdog timer counter is cleared by an external reset or software reset; however, the watchdog timer does
not stop.
●
Intervals
Since a carry signal of the time-base timer is used as the count clock for the interval, the watchdog timer
interval may become longer than the setting time when the time-base timer is cleared.
●
Selecting the interval
The interval can be set when the watchdog timer is activated. Data written during operations other than
activation is ignored.
●
Notes on program creation
When a program that repeatedly clears the watchdog timer in the main loop is created, the processing time
of the main loop including the interrupt processing must be equal to or less than the minimum watchdog
timer interval.
●
Watchdog timer operation in time-base timer mode
The time-base timer operates while the time-base timer mode is set. The watchdog timer, however, is
temporarily stopped.
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