Section 11 Watchdog Timer
11.1
Overview
The H8/3437 Series has an on-chip watchdog timer (WDT) that can monitor system operation by
resetting the CPU or generating a nonmaskable interrupt if a system crash allows the timer count
to overflow.
When this watchdog function is not needed, the watchdog timer module can be used as an interval
timer. In interval timer mode, it requests an WOVF interrupt at each counter overflow.
11.1.1 Features
WDT features are shown below.
•
•
•
Selection of eight counter input clocks
Switchable between watchdog timer mode and interval timer mode
Timer counter overflow generates an internal reset or internal interrupt:
Selection of internal reset or internal interrupt generation in watchdog timer mode
WOVF interrupt request in interval timer mode
•
RESO output in watchdog timer mode
Low-level signal output from RESO pin when counter overflows in watchdog timer mode
(when internal reset is selected)
221
HITACHI [ HITACHI SEMICONDUCTOR ]
