Overview Of Hardware Watchdog Timer - Fujitsu F2MC-8FX Hardware Manual

CHAPTER 12 HARDWARE WATCHDOG TIMER
12.1

Overview of Hardware Watchdog Timer

The hardware watchdog timer serves as a counter used to prevent programs from
running out of control.
Hardware Watchdog Timer Function
The hardware watchdog timer functions as a counter used to prevent programs from running out of control.
Once the hardware watchdog timer is activated, its counter needs to be cleared at specified intervals
regularly. A hardware watchdog reset is generated if the timer is not cleared within a certain amount of
time due to a problem such as the program entering an infinite loop.
The output of RC oscillator is the count clock for the hardware watchdog timer. Table 12.1-1 shows the
minimum and maximum frequency of RC oscillator.
Table 12.1-1 Frequency of RC oscillator
The interval times of the hardware watchdog timer are shown in Table 12.1-2. If the counter of the
hardware watchdog timer is not cleared, a hardware watchdog reset is generated between the minimum
time and the maximum time. Clear the counter of the hardware watchdog timer within the minimum time.
Table 12.1-2 Interval Times of Hardware Watchdog Timer
For information about the minimum and maximum times of the hardware watchdog timer interval, refer to
"12.4 Explanation of Hardware Watchdog Timer Operations and Setup Procedure Example".
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RC oscillator
Count clock
RC oscillator
Frequency
Min. Typ.
50kHz 100kHz
Interval time
Minimum time Maximum time
327.68 ms 2.62 s
(RC=200kHz) (RC=50kHz)
Max.
200kHz