HD6432621 Hitachi, HD6432621 Datasheet - Page 441

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

12.1
A single on-chip watchdog timer channel (WDT0) is provided in the H8S/2623 Series, and two
watchdog timer channels (WDT0 and WDT1) in the H8S/2626 Series. The WDT outputs an
overflow signal (WDTOVF) if a system crash prevents the CPU from writing to the timer counter,
allowing it to overflow. At the same time, the WDT can also generate an internal reset signal for
the H8S/2626 Series or H8S/2623 Series.
When this watchdog function is not needed, the WDT can be used as an interval timer. In interval
timer operation, an interval timer interrupt is generated each time the counter overflows.
12.1.1
WDT features are listed below.
Switchable between watchdog timer mode and interval timer mode
WDTOVF output when in watchdog timer mode
If the counter overflows, the WDT outputs WDTOVF. It is possible to select whether the LSI
is internally reset or an NMI interrupt is generated at the same time.
Interrupt generation when in interval timer mode
If the counter overflows, the WDT generates an interval timer interrupt.
WDT0 and WDT1 respectively allow eight and sixteen types of counter input clock to be
selected
The maximum interval of the WDT is given as a system clock cycle
A subclock may be selected for the input counter of WDT1.
Where a subclock is selected, the maximum interval is given as a subclock cycle
Selected clock can be output from the BUZZ output pin (WDT1)
Overview
Features
Section 12 Watchdog Timer
131072 256.
256 256.
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