Basics of Microcontroller

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By :- Pranshu Mishra

Reg no.:- 20092015


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What is Microcontroller? A microcontroller is a small, low-cost computer-on-a-chip which

usually

includes:

An 8 or 16 bit microprocessor (CPU).

A small amount of RAM.

Programmable ROM and/or flash memory.

Parallel and/or serial I/O.

Timers and signal generators.

Analog to Digital (A/D) and/or Digital to Analog (D/A)conversion.

Often used to run dedicated code that controls one or more tasksin the operation of a device or a system.

Also called embedded controllers, because the microcontrollerand support circuits are often built into, or embedded in, the

devices they control.


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Why do we need to learn Microprocessors/controllers?

The microprocessor is the core ofcomputer systems.

Nowadays many communication, digitalentertainment, portable devices, arecontrolled by them.

A designer should know what types ofcomponents he needs, ways to reduceproduction costs and product reliable


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Microprocessors

General-purpose microprocessor CPU for Computers

No RAM, ROM, I/O on CPU chip itself

ExampleIntels x86, Motorolas 680x0

CPU

General-

Purpose

Micro-processor

RAM ROM I/O

Port

TimerSerial

COM

Port

Data Bus

Address Bus

General-Purpose Microprocessor System


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MICROCONTROLLER

A smaller computer

On-chip RAM, ROM, I/O ports...

ExampleMotorolas 6811, Intels 8051, Zilogs Z8

and PIC 16X

RAM ROM

I/O

PortTimer

Serial

COM

PortMicrocontroller

CPU

A single chip


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MICROPROCESSOR VS MICROCONTROLLER

Microprocessor Microcontroller

CPU is stand-alone, RAM,

ROM, I/O, timer are separate

designer can decide on the

amount of ROM, RAM and I/O

ports.

expensive

versatility

general-purpose

CPU, RAM, ROM, I/O and

timer are all on a single chip

fix amount of on-chip ROM,

RAM, I/O ports

for applications in which cost,

power and space are critical

single-purpose


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WHY MICROCONTROLLER IF WE HAVE

MICROPROCESSOR.. Microprocessors can not stand alone

instruction decoder, ALU, address/data/timing logic, (CPU)

Has no capability to interact with the outside world

memory, I/O ports, UARTS, etc. must be added to make it useful

Microcontrollers are small computing systems on a single chip

Central Processing Unit (CPU)

Program memory

Random Access Memory (RAM) EEPROM - Electrically Erasable Programmable Read Only Memory

A variety of peripheral devices

USARTs, Timer/Counters, ADC, DAC, I/O Ports, CANs, SPIs, etc., etc.


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Features of Microcontroller

A micro-controller is a single integrated circuit,

commonly with the following features:

central processing unit - ranging from small andsimple 4-bit processors to complex 32- or 64-bit

processorsvolatile memory (RAM) for data storage ROM, EPROM, EEPROM or Flash memory for

program and operating parameter storage

discrete input and output bits, allowing control ordetection of the logic state of an individual packagepin

serial input/output such as serial ports (UARTs)


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other serial communications interfaces like IC,

Serial Peripheral Interface and Controller AreaNetwork for system interconnect

peripherals such as timers, event counters, PWMgenerators, and watchdog

clock generator - often an oscillator for a quartztiming crystal, resonator or RC circuit

many include analog-to-digital converters, some

include digital-to-analog converters in-circuit programming and debugging support


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COMPONENTS OF MICROCONTROLLER

From sensors

Single Chip

To actuators

Displays,keyboardetc.

RAM, EPROM,EEPROM, flash
http://www.circuitstoday.com/wp-content/uploads/2011/01/Microcontroller-Structure.gif


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http://www.circuitstoday.com/wp-content/uploads/2011/01/Microcontroller-Structure.gif


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CPU-The Processor core

CPU is the brain of a microcontroller .CPU isresponsible for fetching the instruction, decodes

it, then finally executed. CPU connects every partof a microcontroller into a single system. Theprimary function of CPU is fetching and decodinginstructions. Instruction fetched from program

memory must be decoded by the CPU.


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MEMORY

The function of memory in a microcontroller issame as microprocessor. It is used to store data and

program. A microcontroller usually has a certainamount of RAM and ROM (EEPROM, EPROM,etc) or flash memories for storing program sourcecodes.


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PARALLEL I/O PORTS

Parallel input/output ports are mainly used todrive/interface various devices such as LCDS, LEDS,printers, memories, etc to a microcontroller.

SERIAL PORTS

Serial ports provide various serial interfaces between

microcontroller and other peripherals like parallelports.


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TIMER/COUNTERS

This is the one of the useful function of amicrocontroller. A microcontroller may have morethan one timer and counters. The timers and

counters provide all timing and counting functionsinside the microcontroller. The major operationsof this section is to perform clock functions,modulations, pulse generations, frequencymeasuring, making oscillations, etc. This also canbe used for counting external pulses.


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ANALOG TO DIGITAL CONVERTER(ADC)

ADC converters are used for converting theanalog signal to digital form. The input

signal in this converter should be in analogform (e.g. sensor output) and the outputfrom this unit is in digital form. The digital

output can be use for various digitalapplications (e.g. measurement devices).


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DIGITAL TO ANALOG CONVERTER(DAC)

DAC perform reversal operation of ADCconversion.DAC convert the digital signal

into analog format. It usually used forcontrolling analog devices like DC motors,various drives, etc.


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INTERRUPT CONTROL

The interrupt control is used for providinginterrupt (delay) for a working program .The

interrupt may be external (activated byusing interrupt pin) or internal (by usinginterrupt instruction during programming).


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Types Of Microcontroller

ARM core processors (from many vendors)

Atmel AVR (8-bit), AVR32 (32-bit), and AT91SAM (32-bit)

Cypress Semiconductor PSoC (Programmable System-on-Chip)

Freescale ColdFire (32-bit) and S08 (8-bit)

Freescale 68HC11 (8-bit) Intel 8051

Infineon: 8, 16, 32 Bit microcontrollers

STMicroelectronics STM8 (8-bit), ST10 (16-bit) and STM32

(32-bit) Texas Instruments TI MSP430 (16-bit)

Toshiba TLCS-870 (8-bit/16-bit).


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APPLICATIONS Pocket pagers (low-power, interprets characters, user

interface)

Cameras (low-power, exposure and focus control, userinterface)

"Levelmeter (measures angle, audible and visual user

interface) Keyboard controllers (scanning, debounce, autorepeat,

diagnostics)

Modems (one for data transmission, one for command

processing) Plotters (command interpretation, encoders, motor

control)

Color copiers (paper positioning, color exposure, sensors)


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Charge card pay phones (card reading, dialing, carrier

access) Lawn sprinkler controller (timer, valve control, user

interface)

Instrumentation (user interface, GPIB interface,

compute values) Closed-loop engine control (fuel/air mixture, ignition,

pressure sensing, etc.)

Antilock braking system control (monitors traction,controls brake)

Dynamic ride control (adjusts suspension)


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ADVANTAGES

Microcontrollers act as a microcomputer withoutany digital parts.

As the higher integration inside microcontroller

reduce cost and size of the system. Usage of microcontroller is simple, easy for

troubleshoot and system maintaining.

Most of the pins are programmable by the user for

performing different functions. Easily interface additional RAM, ROM,I/O ports.

Low time required for performing operations.


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DISADVANTAGES

Microcontrollers have got more complex architecturethan that of microprocessors.

Only perform limited number of executionssimultaneously.

Mostly used in micro-equipments.

Cannot interface high power devices directly.


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CONCLUSION

Microcontroller is a single chip micro computer madethrough VLSI fabrication. A microcontroller also called anembedded controller because the microcontroller and its

support circuits are often built into, or embedded in, thedevices they control.

A microcontroller is available in different word lengths likemicroprocessors (4bit,8bit,16bit,32bit,64bit and 128 bit

microcontrollers are available today). Essentially a microprocessor with on-chip memories and

I/O devices.


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Designed for specific functions All in one solution - Reduction in chip count

Reduced cost, power, physical size, etc. Examples

MC68332, MC68HC11, PPC555

Microcontrollers can be embedded in all sorts of everyday

devices They are inexpensive-

even in single pieces You can design complex

functionality in a small package

Basics of Microcontroller

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