The 8051 Microcontrollers

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Odd semester

2013/2014

Mikroprosesor &Mikrokontroler

THE 8051

MICROCONTROLLERS

Prima Dewi Purnamasari1



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OBJECTIVES

Compare and contrast microprocessors and microcontrollers Describe the advantages of microcontrollers for some applications

Explain the concept of embedded systems

Discuss criteria for choosing a microcontroller

Explain the variations of speed, packaging, memory, and cost per unitand how these affect choosing a microcontroller

Compare and contrast the various members of the 8051 family

Compare 8051 microcontrollers offered by various manufacturers

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MICROCONTROLLERS AND EMBEDDED

PROCESSORS

Microcontroller versus general-purposemicroprocessor

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Figure 1 –1 Microprocessor System Contrasted With Microcontroller System



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Table 1 –1

Some Embedded

Products

Using

Microcontrollers

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CHOOSING A MICROCONTROLLER5

C i i f Ch i




Criteria for Choosing a

Microcontroller1. Meet the task efficiently and effectively

1. Size: 8-bit, 16-bit or 32-bit microcontroller

2. Speed

3. Packaging

4. Power consumption

5. Size of RAM and ROM on chip

6. Number of I/O pins & timer on chip

7. Easiness to upgrade to higher performance or lowerconsumption versions

8. Cost per unit2. How easy to develop e.g. programming

language

3. Availability now and future

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A brief history of the 8051

In 1981, Intel Corporation introduced an 8-bitmicrocontroller called the 8051.

128 bytes of RAM

4K bytes of on-chip ROM

two timers one serial port

four I/O ports (each 8-bits wide) all on a single chip.

The 8051 is an 8-bit processor, meaning that the CPU can

work on only 8 bits of data at a time.

Data larger than 8 bits has to be broken into 8-bit pieces

to be processed by the CPU.

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A brief history of the 8051

The 8051 became widely popular after Intel allowed othermanufacturers to make and market any flavors of the 8051they please with the condition that they remain code-compatible with the 8051.

Means: if we write a program for one microcontroller, it will run

on any of them regardless the manufacturer

This has led to many versions of the 8051 with differentspeeds and amounts of on-chip ROM marketed by morethan half a dozen manufacturers.

8051 can have a maximum of 64K bytes of on-chip ROM But many manufacturers have put only 4K bytes on the chip

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8051 Block Diagram9


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Original 8051 Microcontroller

Table 1 –3

Features of the 8051

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8051 Versions11

Table 1 –5

Versions of 8051/52 Microcontroller From Dallas Semiconductor (Maxim)

Table 1 –6 Versions of 8051 From Atmel (All ROM Flash)



Various Speed12

Table 1 –7 Various Speeds of 8051 From Atmel



8052 microcontroller

The 8052 has all the standard features of the8051 as well as an extra 128 bytes of RAM and anextra timer.

8052 has 256 bytes of RAM and 3 timers.

It has 8K bytes of on-chip program ROM insteadof 4K bytes.

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8031 microcontroller

This chip is often referred to as a ROM-less 8051 since ithas 0K bytes of on-chip ROM.

This external ROM must contain the program that the 8031will fetch and execute.

The ROM containing the program attached to the 8031 canbe as large as 64K bytes.

In the process of adding external ROM to the 8031, youlose two ports.

To solve this problem, you can add external I/O to the8031, such as the 8255 chip

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Various 8051 microcontrollers

The 8051 is available in different memory types, such asUV-EPROM, flash, and NV-RAM, all of'which have differentpart numbers.

The UV-EPROM version of the 8051 is the 8751.

The flash ROM version is marketed by many companiesincluding Atmel Corp. and Dallas Semiconductor.

The Atmel Flash 8051 is called AT89C51, while DallasSemiconductor calls theirs DS89C4xO (DS89C420/430/440).

The NV-RAM version of the 8051 made by DallasSemiconductor is called DS5000.

There is also an OTP (one-time programmable) version ofthe 8051 made by various manufacturers.

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Other Members of 8051 Family16

Table 1 –4 Comparison of 8051 Family Members



Reference

The 8051 Microcontroller and Embedded SystemsUsing Assembly and C, 2nd ed., Mazidi, Prentice

Hall, 2006

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The 8051 Microcontrollers

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