MC68HC705MC4MP datasheet(49/180 Pages) FREESCALE

49 / 180 page

General Release Specification

Resets

General Release Specification — MC68HC705MC4

Section 5. Resets

5.1 Contents

5.2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

5.3

External Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

5.4

Internal Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

5.4.1

Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

5.4.2

Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

5.4.3

Computer Operating Properly Reset . . . . . . . . . . . . . . . . . .51

5.2 Introduction

The MCU can be reset from four sources: one external input and three

internal reset conditions. The RESET pin is an input with a Schmitt

trigger as shown in Figure 5-1. The CPU and all peripheral modules will

be reset by the RST signal which is the logical OR of internal reset

functions and is clocked by the internal bus clock. The RESET pin will

also be pulled low by internal reset for four bus cycles.

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MC68HC705MC4MP 数据表(PDF) 49 Page - Freescale Semiconductor, Inc