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8051 VariantsPramod Ranade

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Introduction

8051 family of micro-controllers is themost popular 8 bit micro-controller family.

Original 8051 introduced in 1981 by Intel.

8051 architecture included flexibility toinclude future enhancements.

Today, hundreds of variants of 8051 are

available.

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New features and emerging

trends in new 8051 variants:

More and more on-chip program memory8K (AT89C52)

20K (AT89C55)

64K (P89C51RD2)>64K (for example, 96K in P89C669)

In-System-Programmable (ISP) flashprogram memory

Philips

Dallas

Analog Devices

Many more

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New features and emerging

trends in new 8051 variants:

On-chip external data memory1K (P89C51RD2)

8K (P89C668)

Many more Reduced pin count, for compact designs

AT89C2051 (20 pin package)

Many more

Low voltage / low power consumptionPhilips LPC family (2.7 to 3.3 Volts)

Many more

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New features and emerging

trends in new 8051 variants:

More on-chip peripherals:

A-D converter (P8x552, ADuC8xx, more)

PWM output (several manufacturers)

D-A converter (ADuC8xx, more)

Counters / timers / capture modules (several

manufacturers)

Watchdog timer (several manufacturers)

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New features and emerging

trends in new 8051 variants:

More speed, using various techniques:

Support for higher clock frequencies (upto 33

MHz)

Less clocks per instruction

Extra DPTR

Math co-processor

Combination of above techniques

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New features and emerging

trends in new 8051 variants:

Hardware support for more serialinterfaces:

2 UARTs

Support for other bus standards such as I2C,SPI, CAN, USB

f

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New features and emerging

trends in new 8051 variants:

Architecture extension:

More than 64K program memory

More than 64K data memory

New Instructions

Example: Philips 8051MX family

Upto 8MB program memory

Upto 8MB data memory

New instructions include Universal Pointers

to access 16MB memory space uniformly

N f d i

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New features and emerging

trends in new 8051 variants:

Custom designed 8051:

Buy 8051 core (VHDL source code)

Make necessary changes to add desired

features and/or to remove unwanted features.

Build own 8051 chip (FPGA or ASIC)

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Summary:

Wide choice of micro-controllers isavailable within 8051 family.

Developer can select the optimum 8051variant for own application.

Or design and build own 8051 variant.

Select 8051 development tools that support

all or most variants.