HD6475348R Datasheet, PDF (256/487 Pages) Hitachi Semiconductor – Single-Chip Microcomputer

Section 13 Watchdog Timer
13.1 Overview
The H8/534 and H8/536 have an on-chip watchdog timer (WDT) module. This module can
monitor system operation by generating a signal that resets the entire chip if a system crash allows
the timer count to overflow.
When this watchdog function is not needed, the WDT module can be used as an interval timer. In
the interval timer mode, an interval timer interrupt is requested at each counter overflow.
The WDT module is also used in recovering from the software standby mode.
13.1.1 Features
The basic features of the watchdog timer module are summarized as follows:
• Selection of eight clock sources
• Selection of two modes: watchdog timer mode and interval timer mode
• Counter overflow generates a reset signal or interrupt request
Reset signal in watchdog timer mode; interval timer interrupt request in interval timer mode.
• External output of reset signal
The reset signal generated in watchdog timer mode resets the entire H8/534 or H8/536 chip.
Depending on a reset output enable bit, the reset signal can also be output from the RES pin to
reset devices controlled by the H8/534 or H8/536.
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