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11.1
Overview
The H8/3008 has an on-chip watchdog timer (WDT). The WDT has two selectable functions: it
can operate as a watchdog timer to supervise system operation, or it can operate as an interval
timer. As a watchdog timer, it generates a reset signal for the H8/3008 chip if a system crash
allows the timer counter (TCNT) to overflow before being rewritten. In interval timer operation,
an interval timer interrupt is requested at each TCNT overflow.
11.1.1
Features
WDT features are listed below.
• Selection of eight counter clock sources
φ/2, φ /32, φ /64, φ /128, φ /256, φ /512, φ /2048, or φ /4096
• Interval timer option
• Timer counter overflow generates a reset signal or interrupt.
The reset signal is generated in watchdog timer operation. An interval timer interrupt is
generated in interval timer operation.
• Watchdog timer reset signal resets the entire H8/3008 internally, and can also be output
externally.
The reset signal generated by timer counter overflow during watchdog timer operation resets
the entire H8/3008 internally. An external reset signal can be output from the RESO pin to
reset other system devices simultaneously.
Section 11 Watchdog Timer
299
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