M68HC05 datasheet(61/128 Pages) FREESCALE

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MC68HC05J1A — Rev. 3.0

Technical Data

Parallel Input/Output (I/O)

Technical Data — MC68HC05J1A

Section 7. Parallel Input/Output (I/O)

7.1 Contents

7.2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

7.3

I/O Port Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

7.4

Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

7.4.1

Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

7.4.2

Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

7.4.3

Pulldown Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

7.4.4

Port A External Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

7.5

Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

7.5.1

Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

7.5.2

Data Direction Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

7.5.3

Pulldown Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

7.2 Introduction

This section describes the two bidirectional input/output (I/O) ports.

7.3 I/O Port Function

The 14 bidirectional I/O pins form two parallel I/O ports. Each I/O pin is

programmable as an input or an output. The contents of the data

direction registers determine the data direction of each I/O pin.

All 14 I/O pins have mask-optional, software-programmable pulldown

devices.

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M68HC05 Datasheet(PDF) 61 Page - Freescale Semiconductor, Inc