SH7014 datasheet(325/754 Pages) RENESAS

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11. Watchdog Timer (WDT)

Rev.5.00 Sep. 27, 2007 Page 291 of 716

REJ09B0398-0500

Section 11 Watchdog Timer (WDT)

11.1

Overview

The watchdog timer (WDT) is a 1-channel timer for monitoring system operations. If a system

encounters a problem (crashes, for example) and the timer counter overflows without being

rewritten correctly by the CPU, an overflow signal (

WDTOVF) is output externally. The WDT

can simultaneously generate an internal reset signal for the entire chip.

When the watchdog function is not needed, the WDT can be used as an interval timer. In the

interval timer operation, an interval timer interrupt is generated at each counter overflow. The

WDT is also used in recovering from the standby mode.

11.1.1

Features

The WDT has the following features:

• Works in watchdog timer mode or interval timer mode.

• Outputs WDTOVF in the watchdog timer mode. When the counter overflows in the watchdog

timer mode, overflow signal

WDTOVF is output externally. You can select whether to reset

the chip internally when this happens.

• Generates interrupts in the interval timer mode. When the counter overflows, it generates an

interval timer interrupt.

• Clears standby mode.

• Works with eight counter input clocks.

SH7014 Datasheet(PDF) 325 Page - Renesas Technology Corp