H838532H datasheet(285/508 Pages) RENESAS

Part #	H838532H

Description	16-Bit Single-Chip Microcomputer H8 Family / H8/300H Super Low Power Series

PDF	508 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

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Section 9 Timers

Rev. 1.00 May 30, 2008 Page 265 of 484

REJ09B0436-0100

9.6

Watchdog Timer

9.6.1

Overview

The watchdog timer has an 8-bit counter that is incremented by an input clock. If a system

runaway allows the counter value to overflow before being rewritten, the watchdog timer can reset

the chip internally.

(1) Features

Features of the watchdog timer are given below.

• Incremented by internal clock source (φ/8192 or φw/32).

• A reset signal is generated when the counter overflows. The overflow period can be set from

from 1 to 256 times 8192/

φ or 32/φw (from approximately 4 ms to 1000 ms when φ = 2.00

MHz).

• Use of module standby mode enables this module to be placed in standby mode independently

when not used.

(2) Block Diagram

Figure 9.17 shows a block diagram of the watchdog timer.

PSS

TCSRW

TCW

φ/8192

Notation:

TCSRW:

TCW:

PSS:

φw/32

Reset signal

Timer control/status register W

Timer counter W

Prescaler S

Figure 9.17 Block Diagram of Watchdog Timer

H838532H Datasheet(PDF) 285 Page - Renesas Technology Corp