3069RF-ZTAT Datasheet, PDF (461/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Section 12 Watchdog Timer
12.1 Overview
The H8/3069R 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 H8/3069R 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.
12.1.1 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 H8/3069R internally.
The reset signal generated by timer counter overflow during watchdog timer operation resets
the entire H8/3069R internally.
Rev. 5.0, 09/04, page 439 of 978