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I/O PORTS OF 8051

BY

Ms.S.Preethi

Assistant Professor (SRG)

ECE Department

Kongu Engineering College

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PIN DIAGRAM

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Functions of Ports

PORT 0

  • Normal bidirectional I/O Port
  • Address/data interfacing for accessing external memory
  • Multiplexed address and data bus

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Functions of Ports

PORT 1

  • Normal bidirectional I/O Port

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PORT 2

  • Normal bidirectional I/O Port
  • Used for higher order addresss bus(A8-A15)

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Functions of Ports

PORT 3

  • Normal bidirectional I/O Port
  • Each of its port pin has special functions

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Port-1 Internal Structure

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� Writing ‘1’ to output Pin P1.X

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Writing ‘0’ to output Pin P1.X

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Reading ‘high’ at Input pin P1.X

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Reading ‘low’ at Input pin P1.X

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Port 0-Internal Structure

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Port 2-Internal Structure

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Port 3-Internal Structure

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Thank you