microcontrollers-microcontrollers

8/13/2019 Microcontrollers-Microcontrollers

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Overview of Microprocessors

and Microcontrollers


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Microcontrollers & Microprocessors

A microcontroller(sometimes

abbreviated C, uC or MCU) is a small computer

on a single integrated circuit containing aprocessor core, memory, and programmable

input/output peripherals.

A microprocessorincorporates the functions of

a computer's central processing unit (CPU) on asingle integrated circuit, (IC) or at most a few

integrated circuits


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Microprocessors

It is a multipurpose, programmable device that

accepts digital data as input, processes it

according to instructions stored in its memory,and provides results as output.

It is an example of sequential digital logic, as it

has internal memory.

Intel 4004


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Basic Microprocessor

Architecture

Microprocessors operate on numbers and

symbols represented in the binary numeral

system.


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Functions of Microprocessor

The microprocessor is the master in thesystem, which controls all the activity of thesystem. It issues address and control signals

and fetchesthe instruction and data from memory. Then itexecutes the instruction to take appropriateaction.A microprocessor can perform many differentfunctions (not specific as microcontrollers).


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Architecture

Von Neumann architecture:-One shared memory for instructions(program) and data with one data busand one address bus betweenprocessor and memory.

Harvard architecture :-The Harvard architecture is acomputer architecture with physicallyseparate storage and signal pathwaysfor instructions and data.


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Evolution of Microprocessors

During the 1960s, computerprocessors were constructed out of

small and medium-scale ICs each

containing from tens to a fewhundred transistors.

For each computer built, all of these

had to be placed and soldered ontoprinted circuit boards, and often

multiple boards would have to be

interconnected in a chassis.


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Evolution of Microprocessors

The large number of discrete logicgates used more electrical powerand

therefore, produced more heatthan a more

integrated design with fewer ICs.

The distance that signals had to travelbetween ICs on the boards limited the speed

at which a computer could operate.

In the 1960s, integrated circuits weredeveloped, which placed all of the

components onto a single chip.

In 1971, Intel developed the first

microprocessor, the Intel 4004.


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First Generation

Introduced in 1971 to 1972Serial instructionsEx:- Intel 4004

Introduced November 15, 1971Clock rate 740 kHz0.07 MIPSBus Width 8 bitsPMOS

Number of Transistors 2,300 at 10 mAddressable Memory 640 bytesProgram Memory 4 KB (4 KB)


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Second GenerationLate 1970s16-bit arithmetic and pipelined instruction processing.overlapped fetch, decode, and execute stepsEx:- MC68000, 8080 (Used in home computers).

16-bit processors with minicomputer-likeperformance.The third generation came about as IC transistor

counts approached 2,50,000.The depth of the pipeline increased to five or morestages.

Intels 8086 (Introduced in 1976),ZilogZ8000 MC68020 were the exam les

Third Generation


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Fourth Generation

More than one instruction per clock cycleExample:- 80960CA,Motorolas 88100

Microprocessors in their fifth generation, thedesign soon surpassed 10 million transistors.

In this generation, PCs are a low-margin, high-volume-business dominated by a single

microprocessor (Computer, 1996).

Fifth Generation


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Moores Law


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Microcontrollers

Microcontrollers are designed for embeddedapplications, in contrast tothe microprocessors used in personal computersor other general purpose applications.

Microcontrollers are used in automaticallycontrolled products and devices, such asautomobile engine control systems, implantablemedical devices, remote controls, office

machines, appliances, power tools, toys and

An Intel Die


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Microcontrollers (Contd)

Essentially a microprocessor with on-chip memories and I/O devices

Designed for specific functionsAll in one solution - Reduction in chip

count Reduced cost, power, physical size,

etc.


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Microcontrollers (Contd)

By reducing the size and cost compared to adesign that uses a separate microprocessor,

memory, and input/output devices, microcontrollers

make it economical to digitally control even more

devices and processes. They will generally have the ability to retain

functionality while waiting for an event such as a

button press or other interrupt; power

consumption while sleeping (CPU clock and mostperipherals off) may be just nanowatts, making

many of them well suited for long lasting battery

applications.


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Why Microcontrollers?

The microprocessors Intel 4004 and 8008required external chips to implement a working

system, raising total system cost, and making it

impossible to economically computerize

appliances. Then TI engineers Gary Boone and Michael

Cochran succeeded in creating the first

microcontroller in 1971.

The result of their work was the TMS 1000, whichwent commercial in 1974. It combined read-only

memory, read/write memory, processor and clock

on one chip and was targeted at embedded

systems


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Development of Microcontrollers

Partly in response to the existence of the single-chip TMS 1000, Intel developed a computersystem on a chip optimized for controlapplications, the Intel 8048, with commercialparts first shipping in 1977. It combined RAMand ROM on the same chip.

This chip found its way in over one billion PCKeyboards and other numerous applications.This increased Intel divisions budget by 25%.

Intel introduced a microcontroller 8048 in 1976.But, it came up with a higher performancemicrocontroller 8051.

It took the microcontroller applications to peaks

in the electronic world. This is the most widelyused microcontroller till date.


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Differences in

Microcontrollers Most microcontrollers at this time had two

variants. One had an erasable EPROM program

memory, which was significantly more expensive

than the PROM variant which was only

programmable once. In 1993, the introduction of EEPROM memory

allowed microcontrollers (beginning with the

MicrochipPIC16x84) to be electrically erased

quickly without an expensive package asrequired for EPROM.

In the same year, Atmel produced its first

microcontroller using Flash Technology.


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8051 Microcontroller


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8051 (Contd)

12 MHz clock.

Processor instruction cycle time 1 s.

An 8-bit ALU.

Harvard memory architecturethe externalprogram memory and data memory have

separate address spaces from 0x0000 and

separate control signal(s).

8-bit internal data bus width and 16-bitinternal address busHarvard memory

architecture

CISC (Complex Instruction Set Computer)


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8051 (Contd) Special function registers (SFRs)

PSW (processor status word)

A (accumulator)

B register

SP (stack pointer)

Registers for serial IOs, timers, ports and interrupt .

No floating-point processor No cache

No memory management-unit

No pipeline and

No instruction level parallelism

On-chip RAM of 128 bytes. 32 bytes of RAM also used as four banks (sets) of

registers. Each register-set (bank) thus eight registers.

External data/stack memory can be added up to 64 KBin most version. In certain

8051 enhancements, this limit enhanced to 16 MB


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8051 (Contd)

Two external interrupt pins, INT0 and INT1.

Four ports of 8-bits each in single chip mode.

Two timers.

Serial interface (SI)programmable for three full

duplex UART modes for serial IO.

In certain versionsDMA controller

In certain versionspulse width modulator and

thus support to DAC, d.c and servo motor

controls.

In certain versionsmodem, watchdog timer,

ADC. Advanced versions support these features

and a version is selected as per the system

requirement.


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Picture of 8051 Development

Board


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Questions?


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Thank You!

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