Embadded Report

7/31/2019 Embadded Report

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HARYANA INSTITUTE OF ENGG. AND TECHNOLOGY,KAITHALDEPARTMENT OF ELECTRONICS & COMMUNICATION

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION TO EMBEDDED SYSTEM

1.1.1 DEFINITION

Combination of Software and hardware, designed to perform a particular task.

Examples: Printer, Timers, Remote controls, Digital locks, Lighting control, Keyboard.

An embedded controller is a controller (or computer) that is embedded into some device for some

purpose other than to provide general purpose computing. Perform a single set of functions. Works in

a time constrained environment. Provides high-performance and reliability Mostly Embedded

systems have low cost because they are mass produced in millions. Some Embedded systems have

mechanical moving parts like disk drives as they are less reliable as compared to solid state parts

such as Flash memory.

1.1.2 WHAT IS EMBEDDED TECHNOLOGY

July 12, 2001 Simply put, embedded technology is software or hardware that is hidden

embedded in a large device or system. It typically refers to a fixed function device, as compared

with a PC, which runs general-purpose applications.

Embedded technology is nothing new. It's all around us and has been for years. An early example of

embedded technology is the engine control unit in a car, which measures what settings to give the

engine. Your coffeemaker has embedded technology in the form of a microcontroller, which is what

tells it to make the coffee at 6 a.m. The vending machine has it too. Overall, billions of devices

woven into everyday life use embedded technology.

In the past, embedded technology existed in standalone devicesvending machines and copiers

that did their jobs with little regard for what went on around them. But as technology has learned to

connect devices (mobile phones, PDAs and so on) to the

Internet and to each other, embedded technology's potential has grown. Suddenly it's not so much

about what devices do on their own, but about what they're connected to and what actions those


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connections let them perform. Cell phone companies figured that out a long time ago, which is why

cell phones are cheap and the service, plans are expensive. It's not the phone

Itself that matters, but the connectivity to a vast network of other phones, other people and the

Internet. Similarly, your PDA is just a PDA; until you download software that lets you find a local

restaurant or manage your finances.

Embedded technology has the ability to affect the way you do business and the way you interact with

your customers, no matter what your industry. Let's say you make freezersthe big, expensive kind

that grocery stores buy. You sell one and you're done with that customer. When it breaks, the

customer calls a service person, who probably comes from somewhere other than your company. But

let's say the freezer knows (because embedded technology had been programmed to discover) that it's

about to go on the fritz. Let's say the refrigerator alerts the customer before it breaks (the

technological equivalent of taking aspirin at the hint of a headache). Better yet, let's say the freezer

alerts the manufacturer (you), and you are able to send a service person to do preventative work and

save a lot of Haagen-Dazs from melting. Embedded technology allows all of that to happen. You, the

freezer company, have transformed yourself from a product company to a product and services

company.

The possibilities go beyond that. Programming devices to communicate with businesses (as in the

freezer example above) can eliminate the need for costly call centers. Copy machines that can order

their own replacement cartridges will save businesses time and money. Remember, the fact that the

technology is embedded isn't what's important, and neither is the device. The devices are merely

vessels. Embedded technology, if it's connected to the enterprise, makes sure information gets to the

right place

1.2APPLICATION

Telecom

Mobile phone systems (handsets and base stations), Modems, Routers

Automotive applications

Braking systems, Traction control, Airbag release systems, Engine-

management units, Steer-by-wire systems, Cruise control applications

Domestic appliances

Dishwashers, Televisions, Washing machines, Microwave ovens,


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Video recorders, Security systems, Garage door controllers,

Calculators, Digital watches, VCRs, Digital cameras, Remote

Controls, Treadmills.

RoboticFire fighting robo, Automatic floor cleaner, Robotic arm

Aerospace applications

Flight control systems, Engine controllers, Autopilots, Passenger in-flight

entertainment systems

Medical equipment

An aesthesia monitoring systems, ECG monitors, Pacemakers,

Drug delivery systems, MRI scanners

Defence systems

Radar systems, Fighter aircraft flight control systems, Radio systems,

Missile guidance systems

Office Automation

Laser printers, Fax machines, Pagers, Cash registers, Gas pumps,

Credit/Debit card readers, Thermostats, Grain analyzers


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1.3 APPLICATION AREA

Fig.1.1 Application Area.


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1.4 MARKET REQUIREMENT: -

Embedded Market Globally

Fig.1.2 Market Reqirement


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The world market for embedded systems development is around $250 billion and is expected to grow

at a CAGR of 26%

Cisco, Wind River Systems, Sun Microsystems, Integrated Systems, Microware Systems, and QNX

Software Systems are among the prominent developers of embedded systems.

According to a study, for future of Embedded Systems Technologies, the market for embedded

systems is expected to grow at an average annual growth rate (AAGR) of 16% over the period

Fig.1.3 Market Distribution of Embedded Systems

1.5FUTURE OF EMBEDDED SYSTEMS IN INDIA

At present India exports embedded systems worth to the tune of $10 billion and this could grow to

$50 billion within two to three years. India has a bright future in embedded systems as the

availability of skilled manpower is in abundance.

Embedded system requires considerable domain knowledge, say in automotive, telecom or medical

for which the system has to be designed.

Memory

Embedded boardsDevelopment tools

Embedded SoftwareReal-time operating systems

Embedded processorsMicrocontroller (MCU), Microprocessor (MPU), and

Digital signal processor (DSP)


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1.6EMBEDDED SYSTEM VS. GENERAL COMPUTING SYSTEM

Embedded Systems (ES) usually run out of ROM

ES have resource constraints.

ES are infrequently reprogrammedES often work in reactive mode

ES have hard reliability and correctness constraints


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CHAPTER 2

MICROCONTROLLER

2.1 MICROCONTROLLER

Microprocessors are intended to be general purpose digital computers .Micro controllers are

intended to be special purpose digital controllers .It has a fixed program stored in ROM and doesnt

change over the life time of system. Eight bit CPU with registers A and B

Sixteen bit program counter and data pointer. Eight bit program status word. Eight bit stack pointer.

Internal ROM of 4K.Internal RAM of 128 bytes:

-Four register banks, each containing eight registers

-Sixteen bytes, which may be addressed at bit level

-Eighty bytes of general-purpose data memory

Thirty two input/output pins arranged as four 8-bit ports: P0-P3.Two 16-bit timer/counters: T0 and

T1.Full duplex serial data receiver/Transmitter: SBUF.Control register:TCON,

TMOD,SCON,PCON,IP,and One-Two external and three internal interrupt sources. Oscillator and

clock circuits.


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Microcontroller is a single chip computer.

Fig.2.1 Types Of Microcontroller

2.1.1 History of the 8051

Developed by Intel Corporation in the year 1981.

First 8-bit microcontroller called as 8051

It was called as a Systemon a chip

Intel refers to it as MCS-51

2.2 MICROCONTROLLER CAN BE :

4bit microcontroller



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2.2.1 4BIT MICROCONTROLLERS

:

Most popular microcontroller made in terms ofproduction numbers

Economical

Application: appliances and toys

2.2.2 8BIT MICROCONTROLLERS:

Represent a transition zone between dedicated, high-volume, 4-bit micro-controllers

and the high performance 16 bit microcontrollers 8 bit word size adequate for many computing tasks and control or monitoring applications.

Application: simple appliance control, high-speed machine control, data collection


Provide faster response and more sophisticated calculations

Applications: control of servomechanism like robot arms


Design emphasis is more on high speed computation features and not

on chip features like RAM, ROM, Timers, etc

Applications: robotics, highly intelligent instrumentation, avionics, image

processing, telecommunications, automobiles, etc

ssExample : Intel 80960, ARM


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2.3 PIN DIAGRAM OF 8051

Fig.2.2 Pin Diagram Of 8051

Fig.2.3 Inbuilt structure of microcontroller


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2.3.1 Difference between microprocessor and microcontroller

Microprocessor Micro-controller

1. contain no on chip ram,rom,i/o, timer,

serial port.

1. Contain on chip ram, rom,i/o,timer,serial

port.2. used in general purpose application 2. used in specific purpose application

3. dont provide data storage facilty. 3. provides data storage facility.

4. the structure of p is given below 4. the structure of p is given below

2.4 8051 MICROCONTROLLER

FEATURES OF THE 8051

8 Bit data path and ALU.

On chip flash memory.

4K X 8 ROM - Program memory.

128 x 8 RAM - Data memory.

Multiple 16-bit Timer/Counter.

Full duplex UART (Serial port).

On chip clock oscillator.

32 I/O pins

Six Interrupt sources

8052 MICROCONTROLLER

Has all the features of 8051 along with extra 128 bytes of RAM,

a timer and an extra 4K bytes of on chip ROM


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8051 is upward compatible to 8052

8031 MICROCONTROLLER

ROM-less 8051 i.e. contains 0 K bytes of on chip ROM An external ROM must be added to make it functional

2.5 VERSIONS OF 8051 C

8751 microcontroller:

4K bytes of on chip UV-EPROM, requires PROM burner,as well asUV-EPROM to erase its contents and takes 20 min erase cycle.

AT89C51 from Atmel Corporation:

On chip ROM flash memory, erase cycle in seconds,furnish fastdevelopment.

DS5000 from Dallas Semiconductor:

On chip ROM in form of NV-RAM form. In NV-RAM has ability to

change the ROM contents one byte at a time.

OTP(one time programmable) version of the 8051:

For mass production, low cost.

8051 family from Philips:

One of the largest selections of 8051 microcontrollers, various features

like ADC, DAC, extended I/O, both OTP and flash


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2.6 8051 ARCHITECTURE

2.6.1 HARDWARE DETAILS

2.6.1.1 PIN DIAGRAM

Fig. 2.4. Pin and Block Diagram Of 8051

2.7 PIN DESCRIPTION

Port 1- pins (1-8):

Input/output pins

Contains internal pull-ups.


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Port 3- pins (10-17)

Input/output pins.


Alternate functions to provide signals such as interrupts.

Port 2- pins (21-28):

Input/output port.


Used both as I/O port and higher address byte

Port 0- pins (32-39):

. input/output pins.

. Required external Pull- up resisters of 10 k.

Used both as I/O port and higheraddress byte

PSEN- (pin 29): Program store enable

Active low input

Used while accessing external memory.

Connected to OE pin of external ROM.

ALE- (pin 30): Address Latch Enable

. Active high.

. Used for de-multiplexing the address and data by connecting G pin

of the 74LS373.

EA - (pin 31):

Active low input.

To access external ROM, it must be GND.

XTAL1and XTAL2 - (pin 19 and pin 18):

Provides clock to quartz crystal oscillator.

RST- (pin 9): Reset

Active high input.

Terminate all activities of us.

Sets PC to 0.

Requires minimum 2 machine cycles.

VCC - (pin 40)

GND (pin 20)


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2.8 CRYSTAL STRUCTURE OF 8051:

GND at 20

XTAL 1 pin19 and XTAL at pin 18

Fig. 2.5 Reset Circuit

RESET CIRCUIT OF 8051

RESET pin

Active high. On applying a high pulse to this pin, micro controller will reset and terminate all

activities.

INPUT pin

Minimum 2 machine cycles required to make RESET

Value of registers after RESET


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Fig. 2.6 Reset Switch

2.9 MEMORY ORGANISATION

2.9.1 DATA MEMORY

00-7FH: Direct /indirect addressable.

80H-FFH: Direct addressable

28 bytes are used for SFRs .

SFRs lie between 80H-FFH.

The unused locations are reserved & must not be used

by programmer.

32 locations are bit addressable including 16 SFRs.

External RAM-up to 64k can be attached.


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Fig. 2.7 Data Memory Description Of 8051

2.9.1.2 INTERNAL DATA MEMEORY

Lower 128 bytes: 00H- 7FH

Four register banks: 00H to 1FH

Bit addressable area: 20H to 2FH

General purpose area: 30H to 7FH

SFR address space: 80H to FFH

2.10 8051 REGISTERS

2.10.1 General purpose register

2.10.2 Special Function register

2.10.1 GENERAL PURPOSE REGISTER

Registers (R0-R7): Set of 8 auxiliary registers, namely R0, R1, and R7.

There are 4 such banks in lower RAM.

Data Pointer (DPTR): Made of two 8-bit registers, namely DPH and DPL,

Used to furnish memory address for internal and


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external code access and external data access.

Program Counter (PC): 16-bit register holds the address of the next

program instruction to be executed, automatically

incremented after each instruction fetch.

Stack Pointer (SP): 8-bit register, used to hold an internal RAM

address called the top of the stack.

2.10.2 SPECIAL FUNCTION REGISTER

SFR lies between 80 to FF hex.

Not all address space of 80 to FF is used by SFR.

The unused locations 80H to FFH are reserved &

must not be used by the programmer.

16 addresses are bit addressable.

Special function registers.

Full instruction set including

Variety of addressing modes.

Arithmetic Instruction

Logical Instruction

Branching Instruction

Data movement Instruction

6 interrupt sources.

2.11 SPECIAL FUNCTION REGISTERS

SFR registers can be seen as a sort of control panel for managing and monitoring the microcontroller.

Every register and each of the belonging bits has its name, specified address in RAM and strictly

defined role (e.g. controlling the timer, interrupt, serial connection, etc). Although there are 128

available memory slots for allocating SFR registers, the basic core shared by 8051 MCUs has but 22

registers. The rest has been left open intentionally to allow future upgrades while retaining the

compatibility with earlier models. This fact makes possible to use programs developed for obsolete

models long ago.


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Fig. 2.8 Address Description Of Special Function Registers

2.11.1 CPU REGISTER:

ACC: Accumulator.

B: B registers.

PSW: Program Status Word.

SP: Stack Pointer.

DPTR: Data Pointer (DPH, DPL).

INTERRUPT CONTROL:

IE: Interrupt Enable.

IP : Interrupt Priority.

2.11.2 I/O PORT:

P0: Port 0.

Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL

inputs. When 1s are written to port 0 pins, the pins can be used as high impedance inputs. Port 0 may

also be configured to be the multiplexed low order address/data bus during accesses to external


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program and data memory. In this mode P0 has internal pull-ups. Port 0 also receives the code bytes

during Flash programming, and outputs the code bytes during program verification. External pull-ups

are required during program verification.

P1: Port 1.

Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port 1 output buffers can

sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal

pull-ups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will

source current (IIL) because of the internal pullups.Port 3 also receives some control signals for Flash

programming and verification.

P2: Port 2.

Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can

sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal

pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will

source current (IIL) because of the internal pullups.Port 2 emits the high-order address byte during

fetches from external program memory and during accesses to external data memory that use 16-bit

addresses (MOVX @ DPTR). In this application, it uses strong internal pull-ups when emitting 1s.During accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the

contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and

some control signals during Flash programming and verification.

P3: Port 3.

Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can

sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internalpull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will

source current (IIL) because of the pull-ups. Port 3 also serves the functions of various special

features of the AT89S52 as listed below:


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Fig.2.9 Port Pins Of 8051

ALE/PROG

Address Latch Enable output pulse for latching the low byte of the address during accesses to

external memory. This pin is also the program pulse input (PROG) during Flash programming. In

normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used

for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each

access to external Data Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR

location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise,

the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in

external execution mode.

.

PSEN

Program Store Enable is the read strobe to external program memory. When the AT89S52 is

executing code from external program memory, PSEN is activated twice each machine

Cycle, except that two PSEN activations are skipped during each access to external data memory.

EA/VPP

External Access Enable. EA must be strapped to GND in order to enable the device to fetch code

from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock


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bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for

internal program executions.

STACK POINTER

The Stack Pointer register is 8 bits wide. It is incremented before data is stored during PUSH andCALL executions. While the stack may reside anywhere in on-chip RAM, the Stack Pointer is

initialized to 07H after a reset. This causes the stack to begin at locations 08H.

INTERNAL RAM:

The 128-byte internal RAM, is organized into three distinct areas:

1. Thirty-two bytes from address 00h to 1Fh that make up 32 working registers organized as fourbanks of eight registers each.

2 .A bit addressable area of 16 bytes occupies RAM byte addresses 2oh to 2fh, forming a total of 128

addressable bits.

3. A general purpose RAM area above the bit area, from 30h to 7Fh, adressable as bytes.

Fig. 2.10 Register Bank


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INTERNAL ROM:

In 8051 data memory and program code memory are two different entities.Internal ROM occupies

code addresses 0000h to 0FFFh . If program address exceeds 0FFFh then 8051 automatically fetchescode from external program memory.Code bytes could also be fetched exclusively from external

memory 0000h to FFFFh ,by connecting the EA pin to ground.

TIMERS:

TMOD: Timer mode.

TCON: Timer control.

TH0: Timer 0 high byte.

TL0: Timer 0 low byte. TH1: Timer 1 high byte.

TL1: Timer 1 low byte.

SBUF: SERIAL DATA REGISTERS.

Setting the Baud Rate

Once you have selected the mode of UART, you need to set the Baud Rate.Baud Rate in modes 0 and 2 depends solely on the frequency of quartz crystal. Crystals designed

specifically for this purpose can be found in the market. Although their frequencies might seem a bit

exotic at first (e.g. 11.059 MHz), they produce standard rates for serial communication after the clock

has been divided by the controller.

Baud Rate in modes 1 and 3 is determined by timers T1 and/or T2. Timer T1 is most commonly used

in "Auto-Reload" mode (TMOD = 0010xxxx). In this case, rate is determined by the frequency of

overflow occurrence, and can be calculated according to the formula:

Quartz oscillator frequency

Baud Rate = 384 * (256 - TH1)

If bit SMOD in register PCON is set, rate will be doubled:

Quartz oscillator frequency

Baud Rate = 192 * (256 - TH1)


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Here, bits which are automatically set upon overflow are of no use, and should be cleared to avoid

causing an interrupt. If timer T2 is used for setting the Baud Rate, its bits will always have priority,

allowing the microcontroller to send and receive data at different rates:

RCLK TCLK Mode of work

0 0 Rates of sending and receiving are equal and set by timer T1

only

0 1 Receiving rate is set by T1, sending rate is set by T2

1 0 Receiving rate is set by T2, sending rate is set by T1

1 1 Rates of sending and receiving are equal and set by timer T2

only

OTHER:

PCON: Power control & misc.

A, B REGISTERS

A (Accumulator):

8-bit register & used as working register for

The arithmetic, logical instruction.

Can be used as general purpose register.

Necessary for some instructions.

B REGISTERS:

8-bit register and can be used as general purpose

Register.

Necessary for the instructions MUL and DIV.

.

TMOD : TIMER MODE REGISTER

GATE: Permits INTx pin to enable/disable counter.

C/T : Set for counter operation, reset for timer operation.

M1, M0:

00: Emulate 8048 counter/timer (13-bits).

01:16-bit counter/timer.


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10: 8-bit auto-reload mode

11: Timer 0 = two 8-bit timers.

Timer 1 Counting disabled. Timing function

allowed. Can be used as Baud Rate generator.

This register sets mode for timers T0 and T1. As shown in the image below, lower 4 bits (bit 0 -

bit 3) are associated with T0, while the higher 4 bits (bit4 - bit7) are associated with T1.

Fig.2.11 Tmod Description

The following table gives details on bits 0 - 7:

Bit Bit Name Purpose Timer

7 GATE1 1 Timer works only if INT1 (P3.3) is set

0 Timer works regardless of INT1 (P3.3)

T1

6 C/T1 1 Timer counts impulses on T1 (P3.5)

0 Timer counts impulses of internal

oscillator

T1

5 T1M1 Timer mode T1


3 GATE0 1 Timer works only if INT0 (P3.2) is set

0 Timer works regardless of INT0 (P3.2)

T0

2 C/T0 1 Timer counts impulses on T0 (P3.4)

0 Timer counts impulses of internal

oscillator

T0

1 T0M1 Timer

mode

T0


Four bits from the previous table determine the operating mode of timers T0 and T1. There are 4 of

these modes, and each will be covered in details.


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T0M1 T0M0 Mode Description

0 0 0 13-bit Timer

0 1 1 16-bit Timer

1 0 2 8-bit auto-reload

1 1 3 Splitmode

TIMER MODE

Timer Mode 0 : Emulates 8048 counter/timer (13-bits).

8-bit counter (TL0 or TL1).

5-bit prescaler (TH0 or TH1).

Timer Mode 1: Simple 16-bit counter.

Timer Mode 2: 8-bit auto-reload.

Counterin TL0 or TL1.

Reload value in TH0 or TH1.

Provides a periodic flag or interrupt.

Timer Mode 2: Split timer mode

TCON: TIMER CONTROL REGISTER

TF1, TF0: Overflow flags for Timer 1 and Timer 0.

TR1, TR0: Run control bits for Timer 1 and Timer 0. Set to run

Reset to hold.

IE1, IE0: Edge flag for external interrupts 1 and 0. *

Set by interrupt edge, cleared when interrupt is processed.

IT1, IT0: Type bit for external interrupts. *

Set for falling edge interrupts, reset for 0 level interrupts.

* = not related to counter/timer operation.

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

TCON is another register in direct control of the timers.


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Fig.2.12 Tcon Description

Of the 8 bits, TCON uses only 4 bits for controlling the timers, while the other 4 are associated with

interrupts.

SCON: SERIAL CONTROL REGISTER

SM0, SM1 = Serial Mode Specifier:

00 = Mode 0 : Shift register I/O expansion.

01 = Mode 1 : 8-bit UART with variable baud rate.

10 = Mode 2 : 9-bit UART with fixed baud rate.

11 = Mode 3 : 9-bit UART with variable baud rate.

SM2:

Mode 0: Not used.

Mode 1: 1 = Ignore bytes with no stop bit.

Mode 2, 3: 0 = Set receive interrupt (RI) on all bytes.

: 1 = Set RI on bytes where bit 9 = 1.

REN = Enables receiver.

Bit Bit Name Purpose Timer

7 TF1 This bit is automatically set in

case of overflow in Timer T1

T1

6 TR1 1 - Timer T1 is on

0 - Timer T1 is off

T1

5 TF0 This bit is automatically set in

case of overflow in Timer T0

T0

4 TR0 1 - Timer T0 is on

0 - Timer T0 is off

T0


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TB8 = Ninth bit transmitted (in modes 2 and 3).

RB8 = Ninth bit received:

Mode 0 : Not used.

Mode 1 : Stop bit.

Mode 2,3 : Ninth data bit.

- TI = Transmit interrupt flag.

- RI = Receive interrupt flag.

IE: INTERRUPT ENABLE REGISTER

EA: Global interrupt enable.

ES: Serial interface.

ET1: Timer 1.

EX1: External interrupts 1.

ET0: Timer 0.

EX0: External interrupts 0.

0 = Disabled.

1 = Enabled.

IE (INTERRUPT ENABLE)

Fig.2.12.1 Intrrupt Enable Description

Following table describes the bits of register IE

(same rule applies to all bits - logical state of 1 enables the appropriate interrupt):

Bit Purpose

EA Enables/disables all interrupt sources

ET2 Timer T2 interrupt

ES UART



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EX1 External interrupt: pin INT1


EX0 External interrupt: pin INT0

INTERRUPT PRIORITIES

It cannot be predicted with absolute certainty when will interrupt request take place. If multiple

interrupts are enabled, it's quite possible to have interrupt requests during execution of another

interrupt routine. In such cases, controller needs to resolve whether to proceed with the current

interrupt routine, or to enter a new one, based on a priority check. Our microcontroller can

differentiate between three priority levels:

1. Reset. If there is a request for reset, all processes are halted and the controller behaves as if

the power had just been turned on.

2. Priority 1 interrupts. Can be interrupted only by reset.

3. Priority 2 interrupts. Can be interrupted by any of above.

IP (INTERRUPT PRIORITY)

Fig. 2.13 Intrrupt Priority Description

SFR register IP determines the priority of existing interrupt sources

(Same rule applies to all bits : logical state of 1 assigns higher priority to the appropriate interrupt):

Bit Purpose

PT2 Timer T2 interrupt priority

PS Serial port interrupt priority


PX1 External interrupt INT1 priority



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PX0 External interrupt INT0 priority

If two interrupt requests collide, the one with higher priority has precedence in execution. If both

interrupts are of same priority, the one with the later request has to hold one and let the controller

handle the first one.

HOW DOES INTERRUPT EXECUTE?

Upon receiving an interrupt request, following scenario takes place:

1. Current instruction is executed first.

2. Address of the instruction that would be executed next if there was no interrupt request is put

away to stack.3. Depending on the interrupt in question, program counter will take value of one of possible 6

vectors (addresses) according to the table below.

Interrupt source Vector (address in hex)

IE0 3h

TF0 Bh

IE1 13h

TF1 1Bh

RI, TI, SPIF 23h

TF2, EXF2 2Bh

These addresses should hold the appropriate subroutines for handling the interrupts.

In practice, instead of actual routines, they only point to the location of appropriate routines in thecode.

4. Upon accomplishing the interrupt routine, address of the next instruction to be executed is

retrieved from the stack, and the program proceeds from the location where it was interrupted.

PCON: POWER CONTROL REGISTER

POWER DOWN OPERATION

Setting PD bit stops oscillator.


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RAM contents are saved.

Exit via Reset.

Some (newer) 80C51 derivatives allow Power-Down

wakeup via Interrupt.

IDLE MODE OPERATION

Setting IDL gates clocks off, leaves oscillator running.

All register and RAM contents are saved.

Interrupt sources remain active:

Serial interface.

External interrupts.

Timers.

Exit with any enabled interrupt or Reset.

GF0, GF1 are general purpose software flags.

SMOD serial interface control bit.

Doubles baud rate in modes 1,2, and 3.

Only SMOD available on NMOS parts.


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CHAPTER 3

PROGRAMMING LANGUAGE

3.1 PROGRAMMING IN 8051

3.1.1OBJECTIVE:

Introduction To Programming Language

Addressing Modes

Instruction set

8051 data types and directive

Programming Tools & Techniques

3.2 PROGRAMMING LANGUAGES

3.2.1 Machine Language

3.2.2 Assembly Language

3.2.3 High level language

3.2.1 MACHINE LANGUAGE

A program that consists of 0s and 1s is

Called Machine Language.

Deals directly with the internal structure of

computer.

CPU can work only in machine language.

3.2.2ASSEMBLY LANGUAGE

Defined by a set of rules that specify the

symbols that can be used and they may be

combined to form a line of code.

The instruction has a specific format.


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[Label] mnemonics operand [comment]

Better understanding then machine language.

3.2.3HIGH LEVEL LANGUAGE

The language whose instruction set is more compatible with

Human languages and human thought processes.

HLL offers three significant advantages over machine

language(Simplicity, uniformity and portability).

In HLL the programmer need not to be concern with internal detail

of computer.E.g. BASIC,PASCAL,C,C++,JAVA and numerous other.

Compiler is needed to convert it into machine language.

3.3 ASSEMBLY LANGUAGE SYNTAX

[Label:] Mnemonic [Operands] [Comment]

3.3.1 LABEL

Name of label should be meaningful giving the

refection of the code functionality

E.g.. (LED_ON: Label indicates the switch ON the led)

First character should be an alphabet.

No. of character should not be more than 8

Character. Reserve words must not be used as label.

3.3.2 MNEMONIC & OPERANDS

Mnemonics are assembly opcode specific to C/

P

e.g. MOV All the three opcodes


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LDI are used to move the

STA data/address

The operand can be data or address.

Mnemonics can be of 1 byte & operands can be

byte.

3.3.3 COMMENT

Begin with semicolon comment indicator.

Comments should be small and

meaningful.

Assembler ignores comments, but they are

indispensable to programmer.

3.4 ADRESSING MODES

The various ways of accessing data are

called addressing modes

Immediate addressing mode

Register addressing modeDirect addressing mode

Register indirect addressing mode

Indexed addressing mode

3.4.1 IMMEDIATE ADDRESSING MODE

The operand comes immediately after the

opcode.

Immediate data must be preceded by thepound sign ( # ).

Can be used to load information into any of the

registers and memory location.

MOV A,#25H

MOV R0,#65H

MOV 30H,#20H


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3.4.2 REGISTER ADDRESSING MODE

Involves the use of registers to hold the data to

be manipulated.

MOV A,R0MOV R1,A

ADD A,R6

3.4.3DIRECT ADDRESSING MOD

Eaddress is known.

The address is given as a part of instruction.

MOV 30H, A; Save content of A in RAM location 30hMOV R0, 40H

MOV A, 2

3.4.4REGISTER INDIRECT ADDRESSING MODE

A register is used as a pointer to the data.

As the register hold the address of RAM location

, they must be preceded by @ sign. Only register R0,R1 are used for this purpose

MOV A,@R0

; Move content of RAM location whose address is held by R0 into A.

MOV @R1,B

; Move contents of B into RAM location whose address is held by R1.

3.4.5 INDEXED ADDRESSING MODE Used in accessing data elements of look-up

table located in ROM space.

The 16 bit register DPTR and A are used to

form the address of data element stored in on

chip ROM.

The instruction used for this purpose is

MOVMOVC A,@A+DPTR


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3.4.6 To use C-language instead of assembly language:-

The presence of C-language instead of assembly language to prepare the source code gives designers

and programmers a better ease to write the source code hence increase the efficiency of the circuit

and hence the output.8051 IDE

8051 IDE (Integrated Development Environment)

combines a text editor, Assembler and S/W simulator

into a single Program.

All program needed to develop 8051 program are

available and controllable from this single IDE running onwindows.

KEY FEATURES

Editor

Assembler

Simulator


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CHAPTER 4

INTERFACING

4.1 INTERFACING OF LED

4.1.1 LIGHT EMITTING DIODE:-

Light emitting diodes, commonly called LEDs do dozens of different jobs and are found in all kinds

of devices. Among other things, they form the numbers on digital clocks, transmit information from

remote controls, light up watches and tell you when your appliances are turned on.

Solid state LED light sources are known as p-n semiconductor devices. By doping a substrate

material with different materials, a p-n junction is formed within the semiconductor crystal. The

dopant in the n region provides mobile negative charge carriers (electrons), while the dopant in the p

region provides mobile positive charge carriers (holes). Within a semiconductor crystal, when a

forward voltage is applied to the p-n junction from the p region to the n region, the charge carriers

inject across the junction into a zone where they recombine and convert their excess energy into light.

The materials used at the junction determine the wavelength of the emitted light. LEDs come in a

variety of colures.

4.2 DIODE:-

A diode is the simplest sort of semiconductor device. A semiconductor is a device with a varying

ability to conduct electrical current. Most semiconductors are made of poor conductor that has had

impurities added to it. The process of adding impurities is called doping.

A semiconductor with extra electrons is called N-type material.

A semiconductor with extra holes is called P-type material.

A diode comprises a section of n-type material bonded to a section of p-type material, this

arrangement conducts electricity in only one direction.


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Light is a form of energy that can be released by an atom. It is made up of many small particle-like

packets that have energy and momentum but no mass. These particles, called photons, are the most

basic units of light.

Photons are released as a result of moving electrons. Electrons move in orbital around the nucleus.

As free electrons moving across a diode can fall into empty holes from the P-type layer. This

involves a drop from the conduction band to a lower orbital, so the electrons release energy in the

form of photons .

This happens in any diode, but the photons are seen when the diode is composed of certain material.

Visible light emitting diodes, such as ones that light up numbers in a digital clock are made of

materials characterized by a wider gap between the conduction band and the lower orbital. The size

of the gap determines the frequency of photon; it determines the color of the light.

LEDs have several advantages over conventional incandescent lamps. They dont have a filam ent

that burn out, their small plastic bulb makes them a lot more durable.

Main advantage is the efficiency. LEDs generate very little heat.

The spectral power distribution of an LED is fairly narrow, with half-bandwidths of around 20 to 50

nm, depending upon the substrate material. This means that LEDs produce highly saturated, nearly

monochromatic light. White LEDs are a recent development, constructed by adding a phosphor to a

blue LED. Some of the blue light is converted by the phosphor into broader- spectrum yellow which

results in light that has a bluish-white appearance. White light can also be generated by mixing the

light generated by blue, green and red LEDs.

Materials used in early LEDs to generate specific colors are listed as follows, with the peak spectral

wavelength generated by the LED and the material used (IESNA, 1993):

Deep blue; 470 nm; SiC

Blue; 490 nm; GaN

Red (super bright); 650 nm; AlGaAs

More recently, a promising material for red, amber and yellow LEDs has been identified. Aluminum

indium gallium phosphide (AlInGaP: commonly pronounced like "allen gap") is used to develop long

visible wavelength - yellow, amber and red - LEDs.

LEDs are low-voltage, low-current devices.


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4.2.1 DIODE TESTING:

The conduction of a semiconductor diode can determined quickly using one of the methods that are

following:1. Using DDM(digital display meter)

2. The ohmmeter section of a multimeter.

3. A curve tracer

Out of above these above these methods, diode checking by a multimeter is most common and

widely used. In this method, the forward resistance of a semiconductor diode is measured which is

very low in comparison to reverse bias-level. Thus, if measure the resistance of a diode using the

connections indicated below, we can expect a relatively low level. The resulting ohmmeter indication

will be a function of current established through the diode by the internal battery of the ohmmeter

circuit. The higher is the current, the less the resistance

level while the opposite condition occurs in case of reverse-bias. A high resistance in both directions

obviously indicated an open switch condition, while a very low resistance reading in both directions

will probably indicate a shorted device.

4.2.2DETECTION OF DIODE:-

By detection of a diode, we mean how to check the polarity or the function of a particular diode.

1. POLARITY IDENTIFICATION:-

Different identification schemes are used for different types of diodes. Generally a white or black

band can be seen at cathode but for an LED an anode pin is of greater length than cathode pin.

2. Two classification systems are also available to identify the function of

a diode.

a) European System:

In this type of system, three letters are used as codes in which first letter tells the type of

semiconductor that is

A- for Germanium(Ge) B- for Silicon(Si)


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Second letter tells the function of a diode that is

A- General Purpose B- Tuning

Z- Zener Q- LED

Third letter is for the series. For example BA implies Silicon tuning diode.

b) American System:-

In this system, code 1N is used as first two letters

For example 1N4001, 1N4007 etc. The main drawback of this system is that it does not show the

function of a diode. So, to check the function data sheet of a diode has to be used.

4.3 DIODE CONFIGURATION:-

Diode can be used in any of the following configurations:

1. Common Anode:

In this configuration, +5v dc remains fixed while the ground is supplied by microcontroller. The

concept of current sinking is followed in this case and that is why it is preferred over common

cathode.

2. Common Cathode:

In this type, ground is fixed while a +5v is supplied by the microcontroller. The concept of current

source is followed in this case.

Both of the configurations are shown below:

Fig 4.1 Diode Configuration

\

R4

1k

0uC

0

D5

1 2

R1

1k

R2

1k

R3

1k

D3

1 2

COMMON CATHODE

V1

0Vdc

D2

1 2

COMMON ANODE

D4

1 2


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4.4 INTERFACING OF SEVEN SEGMENTS

4.4.1 SEVEN SEGMENT

A seven-segment display (abbreviation: "7-seg(ment) display"), less commonly known as a seven-

segment indicator, is a form ofdisplay devicethat is an alternative to the more complex dot-matrix

displays. Seven-segment displays are commonly used in electronics as a method of displaying

decimalnumeric feedback on the internal operations of devices.

Fig.4.2 concept and visual structure

A typical 7-segmentLEDdisplay component, with decimal point.

A seven segment display, as its name indicates, is composed of seven elements. Individually on or

off, they can be combined to produce idealized representations of theHindu-Arabic numerals. Each

of the numbers0,6,7and9may be represented by two or more different glyphs on seven-segment

displays.

The seven segments are arranged as a rectangle of two vertical segments on each side with one

horizontal segment on the top and bottom. Additionally, the seventh segment bisects the rectangle

horizontally. There are also fourteen-segment displays and sixteen-segment displays (for full

alphanumerics); however, these have mostly been replaced bydot-matrixdisplays.

Often the seven segments are arranged in an oblique, oritalic, arrangement, which aids readability.
http://en.wikipedia.org/wiki/Display_devicehttp://en.wikipedia.org/wiki/Display_devicehttp://en.wikipedia.org/wiki/Display_devicehttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Decimalhttp://en.wikipedia.org/wiki/Decimalhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Arabic_numeralshttp://en.wikipedia.org/wiki/Arabic_numeralshttp://en.wikipedia.org/wiki/Arabic_numeralshttp://en.wikipedia.org/wiki/0_%28number%29http://en.wikipedia.org/wiki/0_%28number%29http://en.wikipedia.org/wiki/0_%28number%29http://en.wikipedia.org/wiki/6_%28number%29http://en.wikipedia.org/wiki/6_%28number%29http://en.wikipedia.org/wiki/6_%28number%29http://en.wikipedia.org/wiki/7_%28number%29http://en.wikipedia.org/wiki/7_%28number%29http://en.wikipedia.org/wiki/7_%28number%29http://en.wikipedia.org/wiki/9_%28number%29http://en.wikipedia.org/wiki/9_%28number%29http://en.wikipedia.org/wiki/9_%28number%29http://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Fourteen-segment_displayhttp://en.wikipedia.org/wiki/Fourteen-segment_displayhttp://en.wikipedia.org/wiki/Sixteen-segment_displayhttp://en.wikipedia.org/wiki/Sixteen-segment_displayhttp://en.wiktionary.org/wiki/alphanumerichttp://en.wiktionary.org/wiki/alphanumerichttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Image:Sevensegment.jpghttp://en.wikipedia.org/wiki/Image:Sevensegment.jpghttp://en.wikipedia.org/wiki/Image:Sevensegment.jpghttp://en.wikipedia.org/wiki/Image:Sevensegment.jpghttp://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wiktionary.org/wiki/alphanumerichttp://en.wikipedia.org/wiki/Sixteen-segment_displayhttp://en.wikipedia.org/wiki/Fourteen-segment_displayhttp://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/9_%28number%29http://en.wikipedia.org/wiki/7_%28number%29http://en.wikipedia.org/wiki/6_%28number%29http://en.wikipedia.org/wiki/0_%28number%29http://en.wikipedia.org/wiki/Arabic_numeralshttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Decimalhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Dot-matrixhttp://en.wikipedia.org/wiki/Display_device


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The segments of a 7-segment display are referred to by the letters A to G, as follows:

AAAAAA

F B

F B

F B

GGGGGG

E C

E C

E C

DDDDDD DP

where the optional DP decimal point (an "eighth segment") is used for the display of non-integer

numbers. For many applications, dot-matrix LCDs have largely superseded LED displays, though

even in LCDs 7-segment displays are very common. Unlike LEDs, the shapes of elements in an LCD

panel are arbitrary since they are formed on the display by a kind of printing process. Seven-segment

displays are of two types:

4.4.2. COMMON ANODE:

In this type of displays, dc voltage given to it remains fixed while control signals are supplied by

other device that is (logic LOW) by microcontroller. The ML1542 series is used for such displays.

4.4.3. COMMON CATHODE:

In this type of displays, control signals issued by microcontroller are in the form of logic HIGH.

ML5611 series is used for such displays.

Fig.4.3 Internal structures of seven segment
http://en.wikipedia.org/wiki/Decimal_pointhttp://en.wikipedia.org/wiki/Decimal_pointhttp://en.wikipedia.org/wiki/Decimal_point


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4.4.4SINGLE SEVEN SEGMENT:

4.4.5CIRCUIT:

Fig. 4.4 Interfacing with seaven segment

4.5.INTERFACING OF DC MOTOR WITH MICROCONTROLLER

This section begins with an overview of the basic operation of DC motors. Then

we describe how to interface a DC motor to the 8051. Finally, we use C

language programs to demonstrate the concept of pulse width modulation

(PWM) and show how to control the speed and direction of a DC motor.


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4.5.1.DC MOTOR: A direct current (DC) motor is another widely used

device that translates electrical pulses into mechanical movement. In the DC

motor we have only + and - leads. Connecting them to a DC voltage source

moves the motor in one direction. By reversing the polarity, the DC motor will

move in the opposite direction. One can easily experiment with the DC motor.

For example, small fans used in many motherboards to cool the CPU are run by

DC motors. By connecting their leads to the + and - voltage source, the DC

motor moves. While a stepper motor moves in steps of 1 to 15 degrees, the DC

motor moves continuously. In a stepper motor, if we know the starting position

we can easily count the number of steps the motor has moved and calculate the

final position of the motor. This is not possible in a DC motor. The maximum

speed of a DC motor is indicated in rpm and is given in the data sheet. The DC

motor has two rpms: no-load and loaded. The manufacturer's data sheet gives

the no-load rpm. The no-load rpm can be from a few thousand to tens of

thousands. The rpm is reduced when moving a load and it decreases as the load

is increased. For example, a drill turning a screw has a much lower rpm speed

than when it is in the no-load situation. DC motors also have voltage and

current ratings. The nominal voltage is the voltage for that motor under normal

conditions, and can be from 1 to 150V, depending on the motor. As we increase

the voltage, the rpm goes up. The current rating is the current consumption

when the nominal voltage is applied with no load, and can be from 25mA to a

few amps. As the load increases, the rpm is decreased, unless the current or

voltage provided to the motor is increased, which in turn increases the torque.

With a fixed voltage, as the load increases, the current (power) consumption of

a DC motor is increased. If we overload the motor it will stall, and that can

damage the motor due to the heat generated by high current consumption.


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4.5.2 UNIDIRECTIONAL CONTROL:

Figure shows the DC motor rotation for clockwise (CW) and counterclockwise

(CCW) rotations.

Fig.4.5 DC MOTER

4.5.3CIRCUIT DIAGRAM:

Fig4.6 interfacing with DC motor


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CHAPTER 5

5.1RESULT

Microcontrollers producers have been struggling for a long time for attracting more and more

choosy customers. Every couple of days a new chip with a higher operating frequency, more memory

and more high-quality A/D converters comes on the market.

Nevertheless, by analyzing their structure it is concluded that most of them have the same (or at least

very similar) architecture known in the product catalogs as 8051 compatible. What is all this

about?

The whole story began in the far 80s when Intel launched its series of the microcontrollers labeled

with MCS 051. Although, several circuits belonging to this series had quite modest features in

comparison to the new ones, they took over the world very fast and became a standard for what

nowadays is meant by a word microcontroller.

The reason for success and such a big popularity is a skillfully chosen configuration which satisfies

needs of a great number of the users allowing at the same time stable expanding (refers to the new

types of the microcontrollers). Besides, since a great deal of software has been developed in the

meantime, it simply was not profitable to change anything in the microcontrollers basic core. That is

the reason for having a great number of various microcontrollers which actually are solely upgraded

versions of the 8051 family. What is it what makes this microcontroller so special and universal so

that almost all the world producers manufacture it today under different name?


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5.2 CONCLUSION

The training in the DUCAT INSITUTEgave a thorough knowledge about micro controllers. This

training increased my knowledge in how micro controllers are useful as well as used in the real

world.

I am sure that this training would help me a lot in future.


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REFERENCES

Books

Microcontrollers -By Muhammad Mazidi

Microcontrollers -By U.S.Shah

Linear Integrated Circuit -By Gayakwad

Electronics Devices & Circuits -By J. Boylstead

Electronics For You - Monthly Magazine

Various Websites are: www.google.com

www.downloaddatasheets.com

www.atmel.com

www.discovercircuits.com

www.howstuffworks.com

www.analog.com

Documents

Embadded Report