SH7052 datasheet(439/919 Pages) RENESAS

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Section 12 Watchdog Timer (WDT)

12.1

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 standby mode.

12.1.1

Features

The WDT has the following features:

• Works in watchdog timer mode or interval timer mode

• Outputs WDTOVF in watchdog timer mode

When the counter overflows in watchdog timer mode, overflow signal

WDTOVF is output

externally. It is possible to select whether to reset the chip internally when this happens. Either

the power-on reset or manual reset signal can be selected as the internal reset signal.

• Generates interrupts in interval timer mode

When the counter overflows, it generates an interval timer interrupt.

• Clears software standby mode

• Works with eight counter input clocks

SH7052 Datasheet(PDF) 439 Page - Renesas Technology Corp