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Company Profile

Technology changes drastically within the counts of time and it have become vicissitude of

life. To survive in the air of cutthroat competition, one needs to be fully cognizant with the

changing trends of the technology, the needs of the clients and the employers, in brief,

with almost all the aspects o f the industry. There is great demand for system designing

engineers working on the embedded systems. This demand is going to rise further in the

coming years. Other factor favorable for this is the incursion of foreign especiallyAmerican companies in India.

EEAST is a complete R & D Organization dedicated to provide Electronics and

Advanced Software Products and Solutions to its Clients. Achieving the needs of our

customer and converting their ideas to real models is our motto. We are working in the field of

Embedded Systems, Automation and Advanced System design for the last four years with the

vision of becoming a center of Excellence to provide Solutions, Services and Training in

various fields of technologies.

EEAST has the distinction of being a pioneer among the embedded companies in India,

engaged in imparting high-end training in all aspects of Embedded Systems Design and

Project development in various fields of engineering and technology for graduates,

undergraduates and postgraduates of the appropriate discipline, the training at EEAST is not

merely passing knowledge but build intelligence among the participants to achieve goals intheir life by thoroughly exposing them to industrial environment and projects. We work

on overall development of our employees and trainees.

EEAST is an organization providing advanced projects, complete electronic solutions in

development systems like microprocessor, micro - controllers, wireless communications,

optical fiber communications, real time operating systems, digital signal processing,

Embedded Systems and Micro - Sensors including software solution, solutions in C, C++,

Java, .Net, Visual, C++ Visual basic, embedded C and Embedded LINUX. We have been

roviding projects and solutions professionally to various industries, academically to

innumerable number of students. In our endeavor for excellence and manpower

developments in this field, we are providing on these technologies specially customized for

individual needs.

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Introduction

Microcontroller are widely used in Embedded System products. An Embedded product uses

the microprocessor(or microcontroller) to do one task & one task only. A printer is an example

of Embedded system since the processor inside it perform one task only namely getting the

data and printing it. Contrast this with Pentium based PC. A PC can be used for any no. ofapplications such as word processor, print server, bank teller terminal, video game player,

network server or internet terminal. Software for variety of applications can be loaded and run.

Of course the reason a PC can perform multiple task is that it has RAM memory and an

operating system that loads the application software into RAM & lets the CPU run it. In and

Embedded system there is only one application software that is typically burn into ROM. An

x86PC Contain or its connected to various Embedded Products such as keyboard, printer,

modem, Disc controller, Sound card, CD-Rom Driver, Mouse & so on. Each one of these

peripherals as a microcontroller inside it that performs only one task. For example inside every

mouse there is microcontroller to perform the task of finding the mouse position and sending it

to PC.

Although microcontroller are preferred choice for many Embedded systems, There are timesthat a microcontroller is inadequate for the task. For this reason in recent years many

manufactures of general purpose microprocessors such as INTEL, Motorolla, AMD & Cyrix

have targeted their microprocessors for the high end of Embedded market. While INTEL,

AMD, Cyrix push their x86 processors for both the embedded and desktop pc market,

Motorolla is determined to keep the 68000 families alive by targeting it mainly for high end of

embedded system.

One of the most critical needs of the embedded system is to decrease power consumptions and

space. This can be achieved by integrating more functions into the CPU chips. All the

embedded processors based on the x86 and 680x0 have low power consumptions in additions

to some forms of I/O, Com port & ROM all on a single chip. In higher performance Embedded

system the trend is to integrate more & more function on the CPU chip & let the designerdecide which feature he/she wants to use.

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MICROPROCESSOR (MPU)

A microprocessor is a general-purpose digital computer central processing

unit (CPU). Although popularly known as a computer on a chip is in nosense a complete digital computer. The block diagram of a microprocessor

CPU is shown, which contains an arithmetic and logical unit (ALU), a

program counter(PC), a stackpointer (SP),some working registers, a clock

timing circuit, and interrupt circuits.

BLOCK DIAGRAM OF A MICROPROCESSOR

ARITHMETICAND

LOGICAL UNIT

ACCUMULATOR

WORKING REGISTERS

PROGRAMCOUNTER

STACKPOINTER

CLOCKCIRCUIT

INTERRUPTCIRCUITS

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MICROCONTROLLERS (MCU)

Figure shows the block diagram of a typical microcontroller, which is a true

computer on a chip. The design incorporates all of the features found in

micro-processor CPU: ALU, PC, SP, and registers. It also added the other

features needed to make a complete computer: ROM, RAM, parallel I/O,serial I/O, counters, and clock circuit.

BLOCK DIAGRAM OF A MICROCONTROLLER

TIMER / COUNTER

INTERNALROM

ALU I/OPORT

I/O

PORT

Interrupt

Circuits

CLOCK

CIRCUIT

ACCUMULATOR

REGISTERS

INTERNALRAM

ALU

PROGRAM COUNTER

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MICROCONTROLLER ARCHITECTURE

VARIOUS MICROCONTROLLERS

First microcontroller is 8031

FEATURES

(i) It is Intels product. Neither a microprocessor nor a microcontroller.

(ii) It is a 8-bit controller.

(iii) Internally no ROM is provided i.e. code is outside the chip.

Second microcontroller is 8051

FEATURES

(i) It is a first complete 8-bit microcontroller.

(ii) It is a name of a family. In which the instruction set, pin configuration,

architecture are same, only memory storage capacity is different.

(iii) Internally PROM (programmable read only memory) is provided so it

called one time programmable (OTP).

Third microcontroller is AT89C51

FEATURES

(i) It is a similar to 8051 microcontroller i.e. having same instruction set,

pin configuration, architecture.

(ii) It is a also 8-bit microcontroller. Its cost is only Rs10 more than 8051.

(iii) It uses EPROM (erasable programmable read only memory) or

FLASH memory.

(iv) it is Multiple time programmable (MTP)i.e. 1000 times. So it is better

than 8051.

ATMEL 89C51

It is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash

programmable and erasable read only memory (PEROM). The device is manufactured using

Atmels high-density nonvolatile memory technology and is compatible with the industry-

standard MCS-51 instruction set and pin out. The on-chip Flash allows the program memory to

be reprogrammed in system or by a conventional nonvolatile memory programmer. By

combining a versatile 8- bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a

powerful microcomputer, which provides a highly flexible and cost-effective solution to many

embedded control applications

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THE 8051 MICROCONTROLLER

The 8051 provides the following standard features: 4Kbytes of ROM, 128 bytes ofRAM,

32 I/O lines, two16-bit timer/counters, a five vector two-level interrupt architecture, a full

duplex serial port, on-chip oscillator and clock circuitry. In addition, the 8051 is designed

with static logic for operation down tozero frequencyandsupportstwosoftwareselectable

power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/

counters, serial port and interrupt system to continue functioning. The Power Down Mode

saves the RAM contents but freezes the oscillator disabling all other chip functions until

the next hardware reset.

The 8051 Microcontrollers Architectureconsists of thesespecific features

Eight-bit CPU with registers A (the accumulator) & B.

Sixteen-bit program counter (PC) and data pointer (DPTR).

Eight-bit program status word (PSW).

Eight-bit stack pointer (SP).

Internal ROM or EPROM (8751) of 0(8031) to 4K (8051).

Internal RAM of 128 bytes.

1. Four register banks, each containing eight registers.2. Sixteen bytes, which may be addressed at the bit level.3. Eight bytes of general-purpose data memory.

Thirty two I/O pins arranged as four-bit ports P0 P3.

Two 16-bit Timer/Counters T0 and T1.

Full duplex serial data receiver/transmitter (SBUF).

Control registers TCON, TMOD, SCON, PCON, IP and IE.

Two external and three internal interrupt sources.Oscillator and clock circuits

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PIN DESCRIPTION

VCC -- Supply voltage.

GND --Ground.

Port 0 -- Port 0 is an 8-bit open drain bi-directional I/O port. As anoutputport each pin can sink eight TTL inputs. When 1s are written to port 0

pins, the pins can be used as high impedance inputs. Port0 may also be

configured to be the multiplexed low order Address / data bus during

accesses to external program and data memory. In this mode P0 has

internal pull ups. Port 0 also receives the code bytes during ROM

programming, and outputs the code bytes during program verification.

External pull-ups are required during program verification.

Port 1 -- Port 1 is an 8-bit bi-directional I/O port with internal pull-ups . ThePort1 output buffers can sink/source four TTL inputs. When 1s are written

to Port1pins theyarepulled 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 pull-ups. Port 1 also receives

the low-order address bytes during ROM programming and verification.

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Port 2 -- Port 2 is an 8-bit bi-directional I/O port with internal pull-ups . ThePort2 output buffers can sink/source four TTL inputs. When 1s are written

to Port2 pins they are pulledhigh by theinternal pull-ups and can beused

as inputs. As inputs, Port 2 pins that are externallybeing pulled low will

source current (IIL) because of the internal pull-ups. Port2 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 use 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.

Port 3 --Port 3 is an 8-bit bi-directional I/O port with internal pull-ups.ThePort3 output buffers can sink/source four TTL inputs.When 1s are written

to Port3pins they are pulled high by the internal pull-ups andcan 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 receives some

control signals for ROM programming and verification. Port 3 also serves

the functions of various special features of the 8051.

Port Pin Alternate Functions

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write strobe)

P3.7 RD (external data memory read strobe)

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RST -- Reset input. A high on this pin for two machine cycles while theoscillator is running resets the device.

ALE/PROG -- Address Latch Enable output pulse for latching the low

byte of the address during accesses to external memory. This pin isalso the program pulse input (PROG) during ROM 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 programmemory. When the 8051 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 inorder to enable the device to fetch code from external program

memory locations starting at 0000H up to FFFFH. Note, however,

that if lock bit 1 is programmed, EA will be internally latched on

reset. EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage (VPP)

during Flash programming, for parts that require12-volt VPP.

XTAL1Input to the inverting oscillator amplifier and input to theinternal clock operating circuit.

XTAL2-- Output from the inverting oscillator amplifier.

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Memory Organization

There are two types of memory in microprocessor devices.

Program Memory

Data MemoryEach memory type has different addressing mechanism, different control signals and different

function. The Program Memory (ROM or EPROM) is extremely large, read only and non-

volatile. This has a 16-bit address bus, whose elements are accessed by program counter or

instructions that generates 16-bit address.

The Data Memory is a read/write memory space, which is smaller and hence quicker than

program memory. It goes into random state when the electric power is applied. On chip data

RAM is used for variables, which are determined or may change while program is running.

Memory Mapping

Up to 64KB of

External

ROM/PROM

Up to

60KB of

External

ROM/

PROM

4KB of

Internal

ROM/EPROM

Up to 64KB of

External

RAM

SFRs and

128 bytes

RAM

Program Memory Data Memory

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VARIOUS REGISTERS

THE PROGRAM STATUS WORD(PSW)

SF REGISTER

Bit Description

7 6 5 4 3 2 1 0 Bit No.

Bit description

BIT SYMBOL FUNCTION

7 CY Carry flag used in arithmetics, jump, rotate, and rotat

and Boolean instructions.

6 AC Auxiliary Carry flag; used for BCD arithmetic.

5 FO User Flag 0

4 RS1 Register Bank Select Bit 1

3 RS0 Register Bank Select Bit 0

RS1 RS0

0 0 Select Register bank 0




2 OV Overflow flag, used in arithmetic instruction.

1 ___ Reserved for future use

0 P Parity Flag; shows parity of register A

CY AC FO RS1 RS0 OV ___ P

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SPECIAL FUNCTION REGISTERS

The 8051 operations that do not use the internal 128-byte Ram addresses

from 00h to 7Fh are done by a group of specific internal register, each

called a special function register (SFR).

WHAT IS INTERNETWORK?

NAME FUNCTION INTERNALRAM ADD.

A ACCUMULATOR 0E0B ARITHMETIC 0F0

DPH ADDRESSING EXTERNAL MEMORY 83

DPL ADDRESSING EXTERNAL MEMORY 82

IE INTERRUPT ENABLE CONTROL 0A8

IP INTERRUPT PRIORITY 0B8

P0 INPUT/OUTPUT PORT LATCH 80

P1 INPUT/OUTPUT PORT LATCH 90

P2 INPUT/OUTPUT PORT LATCH 0A0

P3 INPUT/OUTPUT PORT LATCH 0B0

PCON POWER CONTROL 87

PSW PROGRAM STATUS WORD 0D0

SCON SERIAL PORT CONTROL 98

SBUF SERIAL PORT DATA BUFFER 99

SP STACK POINTER 81

TMOD TIMER/COUNTER MODE CONTROL 89

TCON TIMER/COUNTER MODE CONTROL 88

TL0 TIMER 0 LOW BYTE 8A

TH0 TIMER 0 HIGH BYTE 8C

TL1 TIMER 1 LOW BYTE 8B

TH1 TIMER 0 HIGH BYTE 8D

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TIMER MODE CONTROL REGISTER(TMOD)

SFR

[ TIMER1 ] [ TIMER0 ]

Bits

7 6 5 4 3 2 1 0 Bit No.

BIT DESCRIPTION

The various bits of TMOD register are explained below:

BIT SYMBOL FUNCTION

7/3 GATE OR gate enable bit which controls RUN/STOP of Timer I/O.

6/2 C/T Set to 1 by program to make timer I/O act as a counter by

counting pulses from external input pin3.5(T1) or 3.4(T0).

5/1 M1 Timer/Counter operating mode select bit1. Set /Cleared byprogram to select mode.

4/0 M0 Timer/Counter operating mode select bit0. Set/Cleared by

program to select mode.

TMOD is not bit addressable.

GATE C/T M1 M0 GATE C/T M1 M0

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TIMER CONTROL (TCON)

Bits7 6 5 4 3 2 1 0 Bit No.

BIT DESCRIPTION

The various bits of TCON registers are explained below:

BIT SYMBOL FUNCTION

7 TF1 Timer 1 overflow flag.

6 TR1 Timer 1 RUN control bit.

5 TF0 Timer 0 overflow flag.

4 TR0 Timer 0 RUN control bit.

3 IE1 External interrupt 1 edge flag.

2 IT1 External interrupt 1 single type control bit.

1 IE0 External interrupt 0 edge flag.

0 IT0 External interrupt 1 single type control bit.

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

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ADDRESSING MODES

The various addressing mode are immediate, register, direct and indirect.Data is stored at a source address and moved (copied) to a destinationaddress. The ways by which these addresses are specified are called the

addressing modes. The 8051 mnemonics are written with the (data)destination address named first, followed by the source address.

1. Immediate Addressing Mode

source ofdata only

2. Register Addressing Mode

Source ordestination of data

3. Direct Addressing Mode

Source or destinationdata

4. IndirectAddressing Mode

Address ofdata

Source or destinationdata

Instruction using # Next bytes are data

Instruction using R0 to R7

Register R0 to R7 in current bank

Instruction using a RAM address

Address in RAM

Instruction using @ R0 or @R1

Register R0 or R1 in current bank

Address in RAM

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Keil Software

Keil software is used for the software implementation of the developed system. Vision2

Integrated Development Environment is an IDE that encapsulates a project manager, make

facility, tool configuration, editor and a powerful debugger. Vision2 is used to write and

compile the programs using the tools. It can transfer the assembly language as well as, C codeinto the hex file. Keil software consists of a Linker Control File, Map File, Project Target,

Source File Group, Toolset. Linker Control File

i) Linker control fileIt is a text file that Vision passes to the linker when linking. The control file includes all

directives and names of object files and library files to include in the output file.

ii) Map FileThe Map File is a listing file generated by the linker.

iii) Project Target:In a project, a target is an executable program that is generated. A project may generate a

target that runs on an 8051. Targets may be created for builds with no optimization and for

builds with full optimization.

iv) Source File Group:In a project, a group is a number of source files that compose the project target. Although you

may individually specify the toolset options for a file, a group lets you apply the same options

to a group of source files. The options for a group may be different from the options for the

target.

v) Toolset:A toolset include an assembler, compiler, linker, HEX converter, debugger, and the otherassociated tools for a particular device family like the 8051. All of the tools or programs in a

toolset are dedicated to generating target code for a specific family of chips [27].

To evaluate the software for correct operation the file was programmed into the

microcontroller on the relevant development board. Programming of the microcontroller was

achieved using the VPL-SPROG programmer. It is a handy serial programmer. This permits

hexadecimal files to be loaded into the microcontroller. Initially the microcontroller was

programmed by removing it from the socket on the board and inserting it into the multi-pin

socket on the programmer.

Section 4.2 describes the programming model and instruction set and section 4.3 describes the

algorithm.

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Power Supply

The power supply supplies the required energy for both the microcontroller and the associated

circuits. It is the most essential part of the circuit because to run its constituent ICs circuit has

to be provided with power. These ICs can run on DC power. Hence the required D.C supply

has to be generated. The main parts of a power supply unit and their function are as follows:

Power supply schematic

DESCRIPTIONPower supply is the main requirement of every project. The various parts of a power supply

are explained below:

Transformer:The function of the transformer is to step down the voltage level from

the available A.C.220V to the desired voltage. The 9-0-9 rating of the transformer upon

the requirements of the ICs in the circuit is used. The secondary has a center tapping

which forms the neutral terminal.

Bridge rectifier: The function of the rectifier is to convert the alternating voltage

signal into a unidirectional one. This function is provided by semiconductor diodes

connected in bridge configuration. Diodes 1N4007 are used as rectifier.

Ripple Rejection:The output voltage of the rectifier is unidirectional but pulsating. A

capacitor of 1000f is used for ripple rejection.

Regulation:To obtain a constant voltage specific ICs are used as voltage regulator.

Voltage regulator LM7805 is used. These ICs have three terminals an input, an output

and a ground terminal.

D2

C1

1000uf

1N4007 +5V

V

LM7805

1 2

3

VIN VOUT

G

N

D

J1

1

2

3

D3

gnd

D4

D1

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LCD Display

Liquid crystal displays (LCD) are widely used in recent years as compares to LEDs.

This is due to the declining prices of LCD, the ability to display numbers, characters and

graphics, incorporation of a refreshing controller into the LCD, their by relieving the CPU

of the task of refreshing the LCD and also the ease of programming for characters and

graphics. HD 44780 based LCDs are most commonly used.

LCD pin description

The LCD discuss in this section has the most common connector used for the Hitatchi

44780 based LCD is 14 pins in a row and modes of operation and how to program and

interface with microcontroller is describes in this section.

Vcc

1615141312111098

654321

7

1615141312111098

65432

1

7

D7

E

Vcc

D4

ContrastRS

Gnd

R/W

Gnd

D0

D3

D6D5

3

2

D2D1

LCD Pin Description Diagram

VCC, VSS, VEE

The voltage VCC and VSS provided by +5V and ground respectively while VEE is

used for controlling LCD contrast. Variable voltage between Ground and Vcc is used to

specify the contrast (or "darkness") of the characters on the LCD screen.

RS (register select)

There are two important registers inside the LCD. The RS pin is used for their selection as

follows. If RS=0, the instruction command code register is selected, then allowing to user

to send a command such as clear display, cursor at home etc.. If RS=1, the data register is

selected, allowing the user to send data to be displayed on the LCD.

R/W (read/write)

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The R/W (read/write) input allowing the user to write information from it. R/W=1, when it

read and R/W=0, when it writing.

EN (enable)

The enable pin is used by the LCD to latch information presented to its data pins. Whendata is supplied to data pins, a high power, a high-to-low pulse must be applied to this pin

in order to for the LCD to latch in the data presented at the data pins.

D0-D7 (data lines)

The 8-bit data pins, D0-D7, are used to send information to the LCD or read the contents of

the LCDs internal registers. To displays the letters and numbers, we send ASCII codes for

the letters A-Z, a-z, and numbers 0-9 to these pins while making RS =1. There are also

command codes that can be sent to clear the display or force the cursor to the homeposition or blink the cursor.

We also use RS =0 to check the busy flag bit to see if the LCD is ready to receive the

information. The busy flag is D7 and can be read when R/W =1 and RS =0, as follows: if

R/W =1 and RS =0, when D7 =1(busy flag =1), the LCD is busy taking care of internal

operations and will not accept any information. When D7 =0, the LCD is ready to receive

new information.

14.7 Interfacing of micro controller with LCD display

In most applications, the "R/W" line is grounded. This simplifies the application

because when data is read back, the microcontroller I/O pins have to be alternated between

input and output modes. In this case, "R/W" to ground and just wait the maximum amount

of time for each instruction (4.1 msecs for clearing the display or moving the cursor/display

to the "home position", 160 usecs for all other commands) and also the application

software is simpler, it also frees up a microcontroller pin for other uses. Different LCD

execute instructions at different rates and to avoid problems later on (such as if the LCD is

changed to a slower unit). Before sending commands or data to the LCD module, the

Module must be initialized. Once the initialization is complete, the LCD can be written to

with data or instructions as required. Each character to display is written like the control

bytes, except that the "RS" line is set. During initialization, by setting the "S/C" bit during

the "Move Cursor/Shift Display" command, after each character is sent to the LCD, the

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cursor built into the LCD will increment to the next position (either right or left). Normally,

the "S/C" bit is set (equal to "1")

Interfacing of Microcontroller with LCD

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ANALOG TO DIGITAL CONVERTER

The ADC (0808) data acquisition component is a monolithic CMOS device with 8-bit

analog to digital converter, 8-channel multiplexer and microprocessor compatible control logic.

The Pin diagram for the ADC 0809 is shown in figure 3.5

Some of the specifications of ADC (0808) are, Resolution of 8 bits, 100 s Conversion

time, Radiometric Conversion, Monotonic Over the entire A/D Conversion Range, No

Missing Codes, Clock range 50 to 800 kHz. It is Easy Interface to all Microprocessors,

Microcontroller and Operates ratio metrically or with 5 VDC or analog span adjusted

voltage reference. The 8bit A /D converter uses successive approximation as the

conversion technique. The converter features a high impedance chopper stabilized

comparator, a 256R voltage divider with analog switch tree and a successive approximationregister. The 8-channel multiplexer can directly access any of 8-single-ended analog

signals. The device eliminates the need for external zero and full-scale adjustments. Easy

interfacing to microprocessor, microcontroller is provided by the latched and decoded

multiplexer address inputs and latched TTL Tri-State outputs. Incorporating the most

desirable aspects of several A/D conversion techniques has optimized the design of the

ADC 0808. The ADC 0808 offers high speed, high accuracy, minimal temperature

OUTPUT ENABLE 9

7

8

5

6

4

3

2

26

27

28

13

12

11

10

16

17

18

19

20

21

22

23

24

25

1IN3

START

IN4

IN5

IN6

IN7

EOC

2-5

CLOCK

VCC

VREF(+)

GND VREF(+)

IN2

IN1

IN0

ADD A

ADD B

ADD C

ALE

2-1 MSB

2-2

2-3

2-4

2-8 LSB

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dependence, excellent long term accuracy and repeatability, and consume minimum power.

These features make this device ideally suited to applications from process and machine

control to consumer and automotive applications. The 8-channel multiplexer can be

controlled by a microcontroller through a 3-bit address decoder with address load to select

any one of eight single-ended analog switches connected directly to the comparator.

Channel 0 of the multiplexer has been selected permanently by grounding the address pins

of multiplexer in the electronics hardware i.e. Pin no. 23, Pin no. 24 and Pin no. 25. The

comparison and the converting methods used eliminate the possibility of missing codes,

nonmonotonicity, and the need for zero or full-scale adjustment. Also featured are latched

3-state outputs from the SAR and latched inputs to the multiplexer address decoder. The

single 5V supply and low power requirements make the ADC 0808 especially useful for a

wide variety of applications. Ratio metric conversion is made possible by access to the

reference voltage input terminals. The ADC 0809 are characterized for operation from 40

0 C to 85 0 C. The ADC 0809/0808 contains a network with 256-300W resistors in series.

Analog switch taps are made at the junction of each resistor and at each end of the network.

In operation, a reference of 5V is applied across the network of 256 resistors. An analog

input VIN is first compared to the center point of the ladder via the appropriate switch. If

VIN is larger than VREF / 2, the internal logic changes the switch points and now

compares VIN and VREF. This process, known as successive approximation, continues

until the best match of VIN and VREF is made. N defines a specific tap of the resistor

network. When the conversion is complete, the logic loads a binary word corresponding to

this tap into the output latch and an end of conversion (EOC) logic level appears. The

output latch holds this data valid until a new conversion is completed and new data is

loaded into the latches. The data transfer occurs in about 100ns so that valid data is present

virtually all the time in the latches. The data outputs are activated when the output enable is

high, and in TRI-STATE when output enable is low. The enable delay time is

approximately 100ns.each conversion requires 40 clock periods. The device may be

operated in the free running mode by connecting the start conversion line to the end of

conversion line. However, to ensure start-up under all possible conditions, an external start

conversion pulse is required during power up conditions. The EOC line (pin 7) will be in

the low state for a maximum of 40 clock periods to indicate busy. A START pulse that

occurs while the A/D is BUSY will reset the SAR and start a new conversion with the EOC

signal remaining in the low state until the end of this new conversion. When the conversion

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is complete, the EOC line will go to the high voltage state. An additional 4 clock periods

must be allowed to elapse after EOC goes high, before a new conversion cycle is requested.

Start conversion pulses that occurs during this last 4 clock period interval may be ignored.

This is a problem only for high conversion rates and keeping the number of conversions

per second less than fCLOCK/44 automatically guarantees proper operation. For example,

for an 800 KHz clock approximately 18,000 conversions per second are allowed. The

reference applied across the 256 networks determines the analog input range. A reference

voltage of 5V is applied to the pin number 12 of the ADC 0808. Since the conversion

completes with in 256 steps. By using VREF = 5V, each step have voltage of 20mv as 5 /

256 = 20mv.The pin numbers 1, 2, 3, 4, 5, 26, 27, 28 of the ADC 0808 describes the 8

multiplexer channels. Any channel can be selected by using three address bits ADDA (pin

25), ADDB (pin 24), ADDC (pin 23). In the hardware channel (INO) pin number 26 is

selected permanently by grounding ADDA, ADDB, ADDC.

The 8-bit digital output we are getting at the pin numbers 21, 20, 19, 18, 8, 15, 14, 17 of

ADC 0808 are connected to port 2 of the 8051 microcontroller. Pin10 of ADC 0809 is for

CLK input. Since ADC 0808 have clock between 50 KHz to 800 KHz. A reference of 5V

is provided at pin12 of ADC 0809. Pin number 16 is grounded and pin 22 is (ALE). ADC

(0808) is low cost IC, cost only RS. 125/- and easily available.

Block diagram of Analog to Digital Converter 0808

13.3 555 TIMER:

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The 555 Timer is used to provide frequency to ADC. The 555 timer IC was first introduced

around 1971 by the signetics corporation as the SE555/NE555 and was called The IC Time

Machine and was also the very first and only commercial timer IC available. It provided

circuit designers with the relatively cheep, stable and user friendly IC for both monostable and

astable applications. The 555 timer use on both analog and digital electronics techniques to

perform its function, but if we consider its o/p only it can be thought of as a digital device. The

o/p of 555 timer can be in one of the two states at any time, which mean it is a digital O/p.

LOW is also known as space for logic 0.

HIGH is also known as mark for logic 1.

13.3.1 Pin Description of 555 TIMER:

Power supply:

Pin 8 is used to connect the positive power supply (Vs) to the 555. This can be any voltage

between 3V and 15V DC, but is commonly 5V DC when working with digital ICs. Pin 1 is the

0V connection to the power supply.

Trigger and Reset Inputs:

Pin 2 is called the trigger input as it is this input that sets the output to the high state. Pin 4 is

called the reset input as it is this input that resets the o/p to the low state. Both pins may be

connected to push buttons to control the operation of the 555.Sometimes the reset input is not

used in a circuit, in which case it is connected directly to Vs to that unwanted resetting cant

occur.

Threshold and discharge:

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Pins 6 and7 (and sometimes the Trigger i/p, pin2) are used to set up the timing aspect of the

555 IC. They are normally connected to a combination of resistors and a capacitor.

Offset:

Pin 5 can be used to alter the timing aspect of the 555 IC in applications such as frequency

modulation.

Output:

Pin 3 is the digital output of the 555.It can be connected directly to the inputs of other digital

ICs, or it can control other devices with the help of a few extra components.

U?

LM555

2 5

3 7 6

4

TR

CV

Q

DIS

THR

R

40

+

11

-

- +

DIODE BRIDGE

1

2

3

4

13

A

1 1Friday, May 18, 2007

Title

Size Document Number Rev

Date: Sheet of

LM 35

0

R?R

LCD

T?

TRANSFORMER

1 5

4 8

SW1

+

Y?

CRYSTAL

-

1 2VS+ VOUT

0-12V

220V

AC

0

SW2

U?

ADC0809

26

27

28

1 2 3 4 5 12

16

10

9 7

17

14

15

8 18

19

20

21

25

24

23

6 22

IN0

IN1

IN2

IN3

IN4

IN5

IN6

IN7

REF+

REF-

CLK

OE

EOC

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

START

ALE

C?

Output 5V DC

J?

CON16

1 2 3 4 5 6 7 8 9 10

11

12

13

14

15

16

7805

C?CAP NP

SW3

1 3VIN VOUT

VCCU?

AT89C52

91819 29

30

31

12345678

2122232425262728

1011121314151617

3938373635343332

RSTXTAL2XTAL1 PSEN

ALE/PROG

EA/VPP

P1.0/T2P1.1/T2-EX

P1.2P1.3P1.4P1.5P1.6P1.7

P2.0/A8P2.1/A9

P2.2/A10P2.3/A11P2.4/A12P2.5/A13P2.6/A14P2.7/A15

P3.0/RXDP3.1/TXD

P3.2/INTOP3.3/INT1

P3.4/TOP3.5/T1

P3.6/WRP3.7/RD

P0.0/AD0P0.1/AD1P0.2/AD2P0.3/AD3P0.4/AD4P0.5/AD5P0.6/AD6P0.7/AD7

Buzzer

20

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Interfacing of MCU with LED:-

A light-emitting diode(LED) is a semiconductor diode that emits incoherent narrow-

spectrum light when electrically biased in the forward direction of the p-n junction. This effect

is a form of electroluminescence.

An LED is usually a small area source, often with extra optics added to the chip that shapes its

radiation pattern. The color of the emitted light depends on the composition and condition ofthe semiconducting material used, and can be infrared, visible, or near-ultraviolet. An LED can

be used as a regular household light source

.

D3

LED

C?CAP NP

D7

LED

D4

LED

D5

LED

D8

LED

U?

AT89C52

91819 29

30

31

12345678

2122

232425262728

1011121314151617

3938

373635343332

RSTXTAL2XTAL1 PSEN

ALE/PROG

EA/VPP

P1.0/T2P1.1/T2-EXP1.2P1.3P1.4P1.5P1.6P1.7

P2.0/A8P2.1/A9

P2.2/A10P2.3/A11P2.4/A12P2.5/A13P2.6/A14P2.7/A15

P3.0/RXDP3.1/TXD

P3.2/INTOP3.3/INT1

P3.4/TOP3.5/T1

P3.6/WRP3.7/RD

P0.0/AD0P0.1/AD1

P0.2/AD2P0.3/AD3P0.4/AD4P0.5/AD5P0.6/AD6P0.7/AD7

D1

LED

R1R

40

D2

LED

Y?

CRYSTAL

VCC

D6

LED

20

Device interfacing with MCU

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Figure no 2.15: Electromagnetic Solenoid Valve

The electromagnetic relay consists of a multi-turn coil, wound on an iron core, to form an electromagnet. When

the coil is energised, by passing current through it, the core becomes temporarily magnetised. The magnetised

core attracts the iron armature. The armature is pivoted which causes it to operate one or more sets of contacts.

When the coil is de-energised the armature and contacts are released. The coil can be energised from a low power

source such as a transistor while the contacts can switch high powers such as the mains supply. The relay can also

be situated remotely from the control source. Relays can generate a very high voltage across the coil whenswitched off. This can damage other components in the circuit. To prevent this a diode is connected across the

coil.

As there are always some chances of high voltage spikes back from the switching circuit i.e. heater so an

optocoupler/isolator MCT2e is used. It provides and electrical isolation between the microcontroller and the

heater. MCT2e is a 6-pin IC with a combination of optical transmitter LED and an optical receiver as

phototransistor. Microcontroller is connected to pin no 2 of MCT2e through a 470-ohm resistor. Pin no.1 is given

+5V supply and pin no.4 is grounded.

To handle the current drawn by the heater a power transistor BC-369 is used as a current driver. Pin no.5 of

optocoupler is connected to the base of transistor. It takes all its output to Vccand activates the heater through

relay circuit. The electromagnetic relay consists of a multi-turn coil, wound on an iron core, to form an

electromagnet. When the coil is energized, by passing current through it, the core becomes temporarily

magnetized. The magnetized core attracts the iron armature. The armature is pivoted which causes it to operate

one or more sets of contacts. When the coil is de-energised the armature and contacts are released. Relays can

generate a very high voltage across the coil when switched off. This can damage other components in the circuit.

To prevent this a diode is connected across the coil. Relay has five points. Out of the 2 operating points one is

permanently connected to the ground and the other point is connected to the collector side of the power transistor.

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When Vcc reaches the collector side i.e. signal is given to the operating points the coil gets magnetized and attracts

the iron armature. The iron plate moves from normally connected (NC) position to normally open (NO) position.

Thus the heater gets the phase signal and is ON. To remove the base leakage voltage when no signal is present a

470-ohm resistance is used.

R4

NO

MCT2E

1 6

2

5

4VCC

RELAY

35

412

BC-369VCC

D11

From P3.0 ofmicrocontroller

J4

HEATER

12

NCphase

R2

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Controlling the Seven Segment Display

The diagram below illustrates an arrangement showing

how a seven segment display can be interfaced along withswitch inputs.

Note the RA0 and RA1 port bits are connected toboth the A1, A0 Switches, the transistor drivers to select the displaydigits.

To drive the display, the RA0 and RA1 bits are configured as

outputs.To input from the two switches,the RA0 and RA1 bitsare configured as inputs. The two 10K resistors preventdamage to the port when configured as outputs and a switchis closed.

30

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USER INTERFACE

The user interface is the aggregate of means by which people (the users)

Interact with a particular machine, device, computer program or other

complex tool (the system). The user interface provides means of: * Input,

allowing the users to control the system* & Output, allowing the system

to inform the users (also referred to as feedback). A good user interface

makes it easy for users to do what they want to do.

The junction between a user and a computer program. An interface is aset ofcommandsormenus through which a user communicates with aprogram. A command-driven interface is one in which you entercommands.A menu-driven interface is one in which you select commandchoices from various menus displayed on the screen. The userinterface

is one of the most important parts of any program because it determineshow easily you can make the program do what we want to. It is widelyaccepted that the user interface can make a critical difference in theperceived utility of a system regardless of the system's performance.

D.C. MOTOR

Working Principle:

The principle upon which the d.c. motor works is very simple . If a

current carrying conductor is placed in a magnetic field, mechanical

force is experienced on the conductor, the direction of which is given

by the Fleming's left hand rule and hence the conductor moves in the

direction of force. The magnitude of the mechanical force experienced

on the conductor is given by:

F = B Ic Lc newtons

where B is the field strength in teslas ,

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Ic is the current flowing through the conductor in amperes

and Lc is the length of the conductor in metres.

When the motor is connected to the d.c. supply mains a direct

current passes through the brushes and the

commutator to the armature winding ; while it passes through the

commutator it is converetd into a.c. so that the group of conductors

under successive field poles carry currrent in the opposite direction.

Also the direction of the currrent in the individual conductors reverse

as they pass away from the influence of one pole to that of the next.

The split phase arrangement of the motor creates two fluxes B1and B2 which

induces voltage around them in the rotor and under the influence of these induced

voltages current flows in the rotor. The current i1 produced by flux B1 reacts with flux

B2 and develops force F1.The quantities are going to be expressed as :

B1=B1max . sin(wt)

B2=B2max . sin(wt + )

It may be assumed with negligible error thet the paths in which the

rotor current flow has negligible self-inductance and hence the rotor

currents are in phase with their respective voltages.

i1(db1/dt)=.B1max.cos wt

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i2(db2/dt)=K. B2 max.cos (wt +X)

Since the two forces (f1and f2 ) developed are in opposition

.Therefore the net force F acting on the movable element is given as:

F=F2-F1(B2.i1-i2.b1)

F=K B1 max.B2 max sin r)

EMF Equation:

Back EMF, Eb=Flux *ZNP/60A

where

Z= total number of armature cunductors

N= Speed in r.p.m

P= total number of poles

A= Total number of parallel paths.

V= Eb + IaRa

.Ia= (V - Eb)/Ra

where

V = Terminal voltage

Ia= Armature current

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Ra= Armature resistance

Eb= back e.m.f.

Types of D.C. motor:

(i) Permanent magnet motors: It consists of an armature and one or

several permanent magnets encircling the armature . Field coils are

usually notrequired. However some of these motors do have coils

wound on the poles .

If they exist , these coils are intended only for recharging the magnets

in the event that they loose their strength.

(ii) Seperately excited D.C. motors: These motors have field coils

similar to those of a shunt wound machine, but the armature and field

coils are fed from diferent supply sources and may have different

voltage ratings.

(iii) Series wound D.C. motor: As the name indicates, the field coils,

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consisting of few turns of a thick wire are connected in series with the

armature. The cross-sectional area of the wire used for the field has to

be fairly large to carry the armature current ,but owing to the higher

current , the number of turns of wire in them need not be large.

(iv) Shunt wound D.C. motor: These motors are so named because

they basically operate with field coils connected in parallel with the

armature.

The field winding consists of a large number of turns of comparatively

fine wire so as to provide large resistance. The field current is much

less than the armature current, sometimes as low as 5%.

(v) Compound wound D.C. motor : A compound wound D.C.

motor has both shunt and series field coils. The shunt field is normally

stronger of the two. Compound wound motors are of two types:.

(a) Cumalative compound wound motor.

(b) Differential compound wound motor.

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Stepper Motor

Motion Control, in electronic terms, means to accurately control the movement of an object based on either speed,

distance, load, inertia or a combination of all these factors. There are numerous types of motion control systems,

including; Stepper Motor, Linear Step Motor, DC Brush, Brushless, Servo, Brushless Servo and more.

A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical

movements. Stepper motor is a form of ac. motor .The shaft or spindle of a stepper motor rotates in discrete step

increments when electrical command pulses are applied to it in the proper sequence. The motors rotation has

several direct relationships to these applied input pulses. The sequence of the applied pulses is directly related to

the direction of motor shafts rotation. The speed of the motor shafts rotation is directly related to the frequency of

the input pulses and the length of rotation is directly related to the number of input pulses applied [39].

For every input pulse, the motor shaft turns through a specified number of degrees, called a step. Its

working principle is one step rotation for one input pulse. The range of step size may vary from 0.72 degree to 90

degree. In position control application, if the number of input pulses sent to the motor is known, the actual

position of the driven job can be obtained.

A stepper motor differs from a conventional motor (CM) as under:

a. Input to SM is in the form of electric pulses whereas input to a CM is invariably from a constant voltage

source.

b. A CM has a free running shaft whereas shaft of SM moves through angular steps.

c. In control system applications, no feedback loop is required when SM is used but a feedback loop is

required when CM is used.

d. A SM is a digital electromechanical device whereas a CM is an analog electromechanical device [40].

3.12.1Open Loop Operation

One of the most significant advantages of a stepper motor is its ability to be accurately controlled in an open loop

system. Open loop control means no feedback information about position is needed. This type of control

eliminates the need for expensive sensing and feedback devices such as optical encoders. Control position is

known simply by keeping track of the input step pulses [39].

Every stepper motor has a permanent magnet rotor (shaft) surrounded by a stator. The most common

stepper motor has four stator windings that are paired with a center-tapped common. This type of stepper motor is

commonly referred to as a four- phase stepper motor. The center tap allows a change of current direction in each

of two coils when a winding is grounded, thereby resulting in a polarity change of the stator. Notice that while a

conventional motor shaft runs freely, the stepper motor shaft moves in a fixed repeatable increment which allows

one to move it to a precise position. This repeatable

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Fig 3.20: Rotor Alignment

fixed movement is possible as a result of basic magnetic theory where poles of the Same polarity repel and

opposite poles attract. The direction of the rotation is dictated by the stator poles. The stator poles are determined

by the current sent through the wire coils. As the direction of the current is changed, the polarity is also changed

causing the reverse motion of the rotor. The stepper motor used here has a total of 5 leads: 4 leads representing the

four stator windings and 1 common for the center tapped leads. As the sequence of power is applied to each stator

winding, the rotor will rotate. There are several widely used sequences where each has a different degree of

precision. Table shows the normal 4-step sequence. For clockwise go for step 1 to 4 & for counter clockwise go

for step 4 to 1.

Winding D

Winding B

1

2

3

4 5 6

Winding DWinding C

Winding A

Fig 3.21: Stator Windings Configuration

Step Winding A Winding B Winding C Winding D

1 0 1 1 1

2 1 0 1 1

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3 1 1 0 1

4 1 1 1 0

Table 3.6: Input Sequence to the Windings

3.12.2 Step Angle & Steps per Revolution

Movement associated with a single step, depends on the internal construction of the motor, in particular the

number of teeth on the stator and the rotor. The step angle is the minimum degree of rotation associated with a

single step.

Step per revolution is the total number of steps needed to rotate one complete rotation or 360 degrees (e.g., 180

steps * 2 degree = 360) [31].

Since the stepper motor is not ordinary motor and has four separate coils, which have to be energized

one by one in a stepwise fashion. We term them as coil A, B, C and D. At a particular instant the coil A should get

supply and then after some delay the coil B should get a supply and then coil C and then coil D and so on the

cycle continues. The more the delay is introduced between the energizing of the coils the lesser is the speed of the

stepper motor and vice versa.

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