Electronic Eye For detecting multi-colors

ELECTRONIC EYE FOR SENSING MULTI-COLOURS

CHAPTER 1

INTRODUCTION

1.1 DESCRIPTION:

In this project an LDR is used the color sensor, which senses color intensity and

converts into voltage with respect to the light intensity. This voltage is converted into the

digital data using analog to digital converter. By this we can get selected compositions of

the radiant light. By using this sensor we can find color of the object. The LDR detects each

color and it gives different voltage levels. Analog to digital converter will take that voltage

and convert it into digital form. These digital values are varying from color to color. Here

ADC0804 is used to convert analog voltage levels into digital 8 bit data.

If this color sensor is irradiant with any color, it produces different voltage outputs

to the microcontroller then microcontroller compares the voltages to the different colors and

displays the corresponding light color on LCD.

1.2 AIM:

This project is aimed to design a system to find out the color of the Object by using

color sensor interfaced to Microcontroller.

1 DEPARTMENT OF ECE, KGRCET


1.3 INTRODUCTION OF EMBEDDED SYSTEM:

An embedded system is a system which is going to do a predefined specified task is

the embedded system and is even defined as combination of both software and hardware. A

general-purpose definition of embedded systems is that they are devices used to control,

monitor or assist the operation of equipment, machinery or plant. "Embedded" reflects the

fact that they are an integral part of the system. At the other extreme a general-purpose

computer may be used to control the operation of a large complex processing plant, and its

presence will be obvious.

All embedded systems are including computers or microprocessors. Some of these

computers are however very simple systems as compared with a personal computer.

The very simplest embedded systems are capable of performing only a single function or set

of functions to meet a single predetermined purpose. In more complex systems an

application program that enables the embedded system to be used for a particular purpose in

a specific application determines the functioning of the embedded system. The ability to

have programs means that the same embedded system can be used for a variety of different

purposes. In some cases a microprocessor may be designed in such a way that application

software for a particular purpose can be added to the basic software in a second process,

after which it is not possible to make further changes. The applications software on such

processors is sometimes referred to as firmware.

The simplest devices consist of a single microprocessor (often called a "chip”),

which may itself be packaged with other chips in a hybrid system or Application Specific

Integrated Circuit (ASIC). Its input comes from a detector or sensor and its output goes to a

switc or activator which (for example) may start or stop the operation of a machine or, by

operating a valve, may control the flow of fuel to an engine.


Software Hardware

ALPCVB Etc.,

ProcessorPeripheralsmemory

Embedded System


Figure.1: Block diagram of Embedded System

Software deals with the languages like ALP, C, and VB etc., and Hardware deals with

Processors, Peripherals, and Memory.

Memory: It is used to store data or address.

Peripherals: These are the external devices connected

Processor: It is an IC which is used to perform some task

Applications of embedded systems

Manufacturing and process control

Construction industry

Transport

Buildings and premises

Domestic service

Communications

Office systems and mobile equipment

Banking, finance and commercial

Medical diagnostics, monitoring and life support

Testing, monitoring and diagnostic systems



Processors are classified into four types like:

Micro Processor (µp)

Micro controller (µc)

Digital Signal Processor (DSP)

Application Specific Integrated Circuits (ASIC)

Micro Processor (µp):

A silicon chip that contains a CPU. In the world of personal computers, the terms

microprocessor and CPU are used interchangeably. At the heart of all personal computers

and most workstations sits a microprocessor. Microprocessors also control the logic of

almost all digital devices, from clock radios to fuel-injection systems for automobiles.

Three basic characteristics differentiate microprocessors:

Instruction set: The set of instructions that the microprocessor can execute.

Bandwidth : The number of bits processed in a single instruction.

Clock speed : Given in megahertz (MHz), the clock speed determines how many

instructions per second the processor can execute.

Fig.2:Three Basic Elements of a Microprocessor

Micro Controller (µc):

A microcontroller is a small computer on a single integrated circuit containing a processor

core, memory, and programmable input/output peripherals. Program memory in the form

of NOR flash or OTP ROM is also often included on chip, as well as a typically small

amount of RAM. Microcontrollers are designed for embedded applications, in contrast to

the microprocessors used in personal computers or other general purpose applications.


http://www.webopedia.com/TERM/M/execute.html

http://www.webopedia.com/TERM/M/processor.html

http://www.webopedia.com/TERM/M/microprocessor.html

http://www.webopedia.com/TERM/M/MHz.html

http://www.webopedia.com/TERM/M/bit.html

http://www.webopedia.com/TERM/M/CPU.html

http://www.webopedia.com/TERM/M/chip.html

http://www.webopedia.com/TERM/M/silicon.html

Timer, Counter, serial communication ROM, ADC, DAC, Timers, USART, Oscillators

Etc.,

ALU

CU

Memory


Fig.3: Block Diagram of Micro Controller (µc)

Digital Signal Processors (DSPs):Digital Signal Processors is one which performs scientific and mathematical

operation.Digital Signal Processor chips - specialized microprocessors with architectures

designedspecifically for the types of operations required in digital signal processing.

Application Specific Integrated Circuit (ASIC)

ASIC is a combination of digital and analog circuits packed into an IC to achieve the desired

control/computation function

ASIC typically contains

CPU cores for computation and control

Peripherals to control timing critical functions

Memories to store data and program

Analog circuits to provide clocks and interface to the real world which is analog in

nature

I/Os to connect to external components like LEDs, memories, monitors etc.



Memory Architecture

There two different type’s memory architectures there are:

Harvard Architecture

Von-Neumann Architecture

Harvard Architecture

Computers have separate memory areas for program instructions and data. There are

two or more internal data buses, which allow simultaneous access to both

instructions and data. The CPU fetches program instructions on the program

memory bus.

Von-Neumann Architecture

The von Neumann architecture is a design model for a stored-program digital

computer that uses a central processing unit (CPU) and a single separate storage

structure ("memory") to hold both instructions and data. It is named after the

mathematician and early computer scientist John von Neumann. Such computers

implement a universal Turing machine and have a sequential architecture.

Conclusion: Before starting practical the theory helped us understand the working

principal.


http://en.wikipedia.org/wiki/SISD

http://en.wikipedia.org/wiki/Universal_Turing_machine

http://en.wikipedia.org/wiki/John_von_Neumann

http://en.wikipedia.org/wiki/Computer_scientist

http://en.wikipedia.org/wiki/Mathematician

http://en.wikipedia.org/wiki/Data_(computing)

http://en.wikipedia.org/wiki/Computer_data_storage

http://en.wikipedia.org/wiki/Computer_data_storage

http://en.wikipedia.org/wiki/Central_processing_unit

http://en.wikipedia.org/wiki/Computer

http://en.wikipedia.org/wiki/Computer


CHAPTER 2

OPERATONAL REPRESENTATON

2.1 BLOCK DIAGRAM:

The Power supply of 230v is stepped-down to 12v.Then the 12v is passed through

bridge rectifier which gives a continues DC output.The DC output s fed to the voltage

regulator which is given to the microcontroller.Power for ADC is fetched from voltage

regulator of 5v.Voltage regulator output is connected for LCD also.


AT89S52

Power Supply

16X2 LCD

ADC 0804/0808

Colored

Specimen

Colored

Specimen

LDR


2.2 POWER SUPPLY:

Block diagram:

OPERATION:

The input voltage to the diodes 1 and 2 is supplied from a transformer and is equal

to the peak AC voltage of the secondary winding of the transformer as shown in

graph 1.

The circuit consisting of the combination of the two diodes is called full wave

rectifier.

These diodes combined with a capacitor are known as full wave rectifier with a

capacitor. This capacitor is known as filtering capacitor improves the output of the

rectifier and the efficiency of this rectifier is 81.2%.

The resistor is used to limit the voltage and current those are supplied to the

regulator in order to avoid the regulator from getting damaged.

The diode 3 is used to protect the diodes 1 and 2 from the back current discharged

by the capacitor.

The output at this point is not completely regulated since there is still some amount

of ripple present in the rectified voltage.

Therefore a regulator is used to ensure low voltage ripple and excellent load and line

voltage regulation.

The resistor after the regulator is used to limit the current supplied to the LED.

When the voltage supplied is greater than 3.8V, the LED will glow. The regulated

DC voltage output is taken across the capacitor and is further supplied to other

applications.



CHAPTER 3

CIRCUIT SCHEMATICS

3.1 SCHEMATIC CIRCUIT DIAGRAM:

The following schematic explanation includes the detailed pin connections of every device

with the microcontroller.



3.2 SYSTEM WORKING:

Fig.4:Working of system

Power Supply:

The main aim of this power supply is to convert the 230V AC into 5V DC in order to give

supply for the TTL or CMOS devices. In this process we are using a step down transformer, a bridge

rectifier, a smoothing circuit and the RPS.

At the primary of the transformer we are giving the 230V AC supply. The secondary is

connected to the opposite terminals of the Bridge rectifier as the input. From other set of opposite

terminals we are taking the output to the rectifier.

The bridge rectifier converts the AC coming from the secondary of the transformer into

pulsating DC. The output of this rectifier is further given to the smoother circuit which is capacitor



in our project. The smoothing circuit eliminates the ripples from the pulsating DC and gives the

pure DC to the RPS to get a constant output DC voltage. The RPS regulates the voltage as per our

requirement.

LCD module:

This module is used to display the status of the devices.This module consists of 8 data lines

D0 – D7, which are connected to the 8 pins of port1 (P0). Additionally this module is having 3

control lines namely RS, RW and EN, which are connected to the port2 higher pins P2.7, P2.6 and

P2.5 respectively. And the supply connections are given from the Power supply output 7805 to the

VCC and VSS.

Microcontroller:

The microcontroller AT89S52 with Pull up resistors at Port0 and crystal oscillator of 11.0592

MHz crystal in conjunction with couple of capacitors of is placed at 18 th & 19th pins of 89S52 to

make it work (execute) properly.

LED:

All the three LED’s (Red,Green,Blue) are connected in parallel for power.A power

of 5v,an output,ground are connected to the ADC for data processing.



CHAPTER 4

HARDWARE DESCRIPTION

4.1 DESCRIPTION OF MICROCONTROLLER AT89S52:

The AT89S52 is a low-power, high-performance CMOS 8-bit micro controller with

8Kbytes of in-system programmable Flash memory. The device is manufactured Using

Atmel’s high-density non-volatile memory technology and is compatible with the industry-

standard 80C51 micro controller. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional non-volatile memory programmer. By

combining a versatile 8-bit CPU with in-system programmable flash one monolithic chip;

the Atmel AT89S52 is a powerful micro controller, which provides a highly flexible and

cost-effective solution to many embedded control applications.

The AT89S52 provides the following standard features: 8K bytes of Flash, 256

bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters,

full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is

designed with static logic for operation down to zero frequency and supports two software

selectable 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.



4.2 Architecture of 8052:

Fig.5: Architecture of 8052.



PIN CONFIGURATION & DESCRIPTION OF MICROCONTROLLER AT89S52

Fig.6: Pin configuration of AT89S52

PIN DESCRIPTION OF MICROCONTROLLER AT89S52:

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 1sare written to port 0 pins, the pins can be used as high

impedance inputs. Port 0 can 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 Flash 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. 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. In addition, P1.0 and P1.1 can be

configured to be the timer/counter 2 external count input

(P1.0/T2) and the timer/counter 2 trigger input P1.1/T2EX), respectively, as shown

in the following table. Port 1 also receives the low-order address bytes during Flash

programming and verification.

Table 1: Port 1 functions

Port 2:

Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. 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. Port 2 emits the high-order address

byte during fetches from external program memory and during accesses to external data

memory that uses 16-bit addresses (MOVX @DPTR). In this application, Port 2 uses strong

internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit

addresses (MOVX @ RI), Port 2emits 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. 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.

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 writen 1s are written to Port 3 pins,



they are pulled high by the internal pull-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 shown in the

following table. Port 3 also receives some control signals for Flash programming and

verification.

Table 2: Port 3 functions

RST:

Reset input. A high on this pin for two machine cycles while the oscillator is running

resets the device.

ALE/PROG:

Address Latch Enable is an output pulse for latching the low byte of the address during access 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 1/16 the oscillator frequency and may be

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

each access to external Data memory.

PSEN

Program Store Enable (PSEN) 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 bit 1 is programmed, EA will be internally latched on reset. A

should be strapped to VCC for internal program executions. This pin also receives the 12-

voltProgramming enables voltage (VPP) during Flash programming.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

XTAL2:

Output from the inverting oscillator amplifier.

Oscillator Characteristics:

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier

that can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz

crystal or ceramic resonator may be used. To drive the device from an External clock

source, XTAL2 should be left unconnected while XTAL1 is driven, as shown.

Special Function Register (SFR) Memory:

Special Function Registers (SFR s) are areas of memory that control specific

functionality of the 8051 processor. For example, four SFRs permit access to the 8051’s 32

input/output lines. Another SFR allows the user to set the serial baud rate, control and

access timers, and configure the 8051’s interrupt system.

The Accumulator:

The Accumulator, as its name suggests is used as a general register to accumulate

the results of a large number of instructions. It can hold 8-bit (1-byte) value and is the most

versatile register.



The “R” registers:

The “R” registers are a set of eight registers that are named R0, R1. Etc up to R7.

These registers are used as auxiliary registers in many operations.

The “B” registers:

The “B” register is very similar to the accumulator in the sense that it may hold an

8-bit (1-byte) value. Two only uses the “B” register 8051 instructions: MUL AB and DIV

AB.

The Data Pointer:

The Data pointer (DPTR) is the 8051’s only user accessible 16-bit (2Bytes)

register. The accumulator, “R” registers are all 1-Byte values. DPTR, as the name suggests,

is used to point to data. It is used by a number of commands, which allow the 8051 to

access external memory.

THE PROGRAM COUNTER AND STACK POINTER:

The program counter (PC) is a 2-byte address, which tells the 8051 where the next

instruction to execute is found in memory. The stack pointer like all registers except DPTR

and PC may hold an 8-bit (1-Byte) value.

ADDRESSING MODES:

An “addressing mode” refers that you are addressing a given memory location. In

summary, the addressing modes are as follows, with an example of each:

Each of these addressing modes provides important flexibility.

Immediate Addressing MOV A, #20 H

Direct Addressing MOV A, 30 H

Indirect Addressing MOV A, @R0

Indexed Addressing



a.External Direct MOVX A, @DPTR

b.Code In direct MOVC A, @A+DPTR

Timer 2 Registers:

Control and status bits are contained in registers T2CON and T2MOD for

Timer 2. The register pair (RCAP2H , RCAP2L) are the Capture / Reload registers for

Timer 2 in 16-bit capture mode or 16-bit auto-reload mode .

Interrupt Registers:

The individual interrupt enable bits are in the IE register . Two priorities can

be set for each of the six interrupt sources in the IP register.

Sy

mbol

Posit

ion

Function

EA

IE.7 Disables all interrupts.if EA=C.no interrupt is

acknowledged.if EA=1.each interrupt source is

individually enabled or desabled by setting or clearing

its erasable bit.

-- IE.6 Reserved.12

ET2 IE.5 Timer 2 interrupt enable bit.

ES IE.4 Serial port interrupt enable bit.

ET IE.3 Timer 1 interrupt enable bit.

EX1 IE.2 External interrupt 1 enable bit.

ET0 IE.1 Timer 0 interrupt enable bit.

EX0 IE.0 External interrupt 0 enable bit.



Table 3: Interrupt registers functions

Timer 2:

Timer 2 is a 16-bit Timer / Counter that can operate as either a timer or an

event counter. The type of operation is selected by bit C/T2 in.

The SFR T2CON. Timer 2 has three operating Modes : capture , auto-reload

( up or down Counting ) , and baud rate generator . The modes are selected by bits in

T2CON. Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the

TL2 register is incremented every machine cycle. Since a machine cycle consists of 12

oscillator periods, the count rate is 1/12 of the oscillator frequency. In the Counter

function , the register is incremented in response to a 1-to-0 transition at its

corresponding external input pin , T2 .When the samples show a high in one cycle

and a low in the next cycle, the count is incremented . Since two machine cycles (24

Oscillator periods ) are required to recognize 1-to-0 transition , the maximum count

rate is 1 / 24 of the oscillator frequency .



TCON REGISTER:

Table 4: Timer/counter Control Register



TMOD REGISTER:

7 6 5 4 3 2 1 0

GATE1 C/T1# M11 M01 GATE0 C/T0# M10 M00

Bit

numbe

r

Bit

Mnemonic

Description

7 GATE1 Timer 1 gating control BitClear to enable timer 1 whenever the TR1 bit is set.Set to enable timer 1 only while the INT1# pin is high and TR1 bit is set.

6 C/T1# Timer 1 Counter/Timer select bitClear for timer operation:timer 1 counts the divide-down system clock.Select Counter operation:timer 1 counts negative transitions on external pin l 1.

5 M11 Timer 1 Mode Select Bits.

4 M01 M11 M01 Operating mode 0 0 mode 0:8-bit timer/counter (TH1) with 6-bit proscalar(TL1). 0 1 mode 1:16-bit timer/counter. 1 0 mode 2:8-bit auto-reload timer/counter (TL1).Reloaded from TH1 at overflow. 1 1 mode 3:timer 1 halted.Routine count.

3 GATE0 Timer 0 Gating Control BitClear to enable timer 0 whenever the TR0 bit is set.Set to enable timer/counter 0 only while the INT0#pin is high and the TR0 bit is set.

2 C/T0# Timer 0 counter/timer select BitClear Timer operation:timer 0 counts the divided-down system clock.Set for counter operation:timer 0 counts negative transitions on external pin T0.

1 M10 Timer 0Mode select Bit



0 M00 M11 M01 Operating mode 0 0 mode 0:8-bit timer/counter (TH0) with 6-bit proscalar(TL0). 0 1 mode 1:16-bit timer/counter. 1 0 mode 2:8-bit auto-reload timer/counter (TL0).Reloaded from TH0 at overflow. 1 1 mode 3:TL0 is an 8-bit timer/counter. TH0 is an 8-bit timer using timer 1’s TR0 and TF0 bits.

Table 5: Timer/Counter 0 and 1 Modes

4.3 ANALOG TO DIGITAL CONVERTER – ADC

Analog to digital converters are among the most widely used devices for data

acquisition. Digital computers use binary values, but in physical world everything is analog.

Temperature, pressure, humidity, are a few examples of physical quantities that we deal

with everyday. A physical quantity is converted to electrical signals using a device called a

transducer. Transducers are also referred to as sensors. Sensors for temperature, velocity,

pressure, light, and many other natural quantities produce an output that is voltage(or

current). Therefore, we need an analog to digital converter to translate analog signals to

digital numbers so that microcontroller can read and process them. An ADC has n-bit

resolution where n can be 8,10,12,16 or even 24 bits. The higher resolution ADC provides

smaller step size, where step size is the smallest change that can be discerned by an ADC.

In addition to resolution, converter time is another major factor in judging an ADC.

Conversion time is defined as the time it takes the ADC to convert the analog input to

digital number.Commonly used ADC device – ADC804.

ADC0804 CHIP:

The ADC0804 IC is an 8 bit parallel ADC in the family of the ADC0800

series. In ADC0804, the conversion time varies depending on the clocking signals applied

to the CLK IN pin, but it can not be faster than 110micro seconds.

Pin diagram:



Fig 7: ADC Pin diagram

• CS – Chip Select , active low

• RD – Read Digital data from ADC, H-L edge triggered

• WR -- Start conversion, L-H pulse edge triggered

• INTR -- end of conversion, Goes low to indicate conversion done

• Data bits -- D0-D7

• CLK IN & CLK R

– CLK IN is an input pin connected to an external clock source when an external clock is

used for timing. However, ADC804 has an internal clock

generator.

To use the internal clock generator of the ADC804, the CLK IN and CLK R pins are

connected to a capacitor and a resistor. In that case, the

clock frequency is determined by the equation.

f = 1/1.1RC

R=10K and C=150pF f=606Hz

the conversion time is 110us.

Input Voltage range

• Default 0-5V. Can be changed by setting different value for Vref/2 pin.

Vin=Vin(+) – Vin (-)

• Range = 0 to 2x Vref/2.

for Vin = 2x Vref/2. we get 256 as a digital output on D0-D7. (Refer Table)

•Step Size is a Smallest change

– (2 x Vref/2)/ 256 for ADC804



for eg for step size 10mv ,digital output on D0-D7 changes by one count for every 10mv

change of the input analog voltage.

Data out

Dout = Vin / Step Size

for input vtg. of 2.56 volts (Vref=1.28 volts) and stepsize of 10mv Dout =2560/10 =256 or

FF that is full scale output.

4.4 INTERFACING ADC804 TO 8052 MCRO CONTROLLER

Signals to be interfaced (on the ADC804)

D0-D7, RD, WR, INTR, CS

Can do both Memory mapping and IO mapping

Memory Mapping (timing is critical)

Connect D0-D7 of ADC804 to the data bus of the 8051 system

Connect RD, WR of the ADC804 to the 8051 system (ensure polarity)

Connect CS of ADC804 to an appropriate address decoder output

Connect INTR of ADC804 to an external interrupt Pin on the 8051 (INT0 or INT1)

IO Mapping (easiest - I prefer )

Connect D0-D7, RD, WR, CS, INTR to some port bits on the 8051 (12 in all).

Algorithm

Make CS=0 and send a low-to-high to pin WR to start the conversion.

Keep monitoring INTR

If INTR =0, the conversion is finished and we can go to the next step.

If INTR=1, keep polling until it goes low.

After INTR=0, we make CS=0 and send a high-to-low pulse to RD to get the data out of

the ADC804 chat



4.5 LCD DISPLAY (LIQUID CRYSTAL DISPLAY):

A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or

video display that uses the light modulating properties of liquid crystals. Liquid crystals do

not emit light directly.

LCDs are available to display arbitrary images (as in a general-purpose computer

display) or fixed images which can be displayed or hidden, such as preset words, digits, and

7-segment displays as in a digital clock. They use the same basic technology, except that

arbitrary images are made up of a large number of small pixels, while other displays have

larger elements.

LCDs are used in a wide range of applications including computer monitors,

televisions, instrument panels, aircraft cockpit displays, and signage. They are common in

consumer devices such as video players, gaming devices, clocks, watches, calculators, and

telephones, and have replaced cathode ray tube (CRT) displays in most applications. They

are available in a wider range of screen sizes than CRT and plasma displays, and since they

do not use phosphors, they do not suffer image burn-in. LCDs are, however, susceptible to

image persistence.[1]

The LCD screen is more energy efficient and can be disposed of more safely than a

CRT. Its low electrical power consumption enables it to be used in battery-powered

electronic equipment. It is an electronically modulated optical device made up of any

number of segments filled with liquid crystals and arrayed in front of a light source

(backlight) or reflector to produce images in color or monochrome. Liquid crystals were

first discovered in 1888.[2] By 2008, worldwide sales of televisions with LCD screens

exceeded annual sales of CRT units; the CRT became obsolete for most purposes.

LCD is finding wide spread use replacing LEDs because of the following reasons

The declining prices of LCDs.

The ability to display numbers, characters and graphics. This is in contrast to LEDs,

which are limited to numbers and a few characters.

Ease of programming for characters and graphics.


https://en.wikipedia.org/wiki/Liquid-crystal_display#cite_note-2

https://en.wikipedia.org/wiki/Monochrome

https://en.wikipedia.org/wiki/Reflector_(photography)

https://en.wikipedia.org/wiki/Backlight

https://en.wikipedia.org/wiki/Light#Light_sources

https://en.wikipedia.org/wiki/Liquid_crystal

https://en.wikipedia.org/wiki/Electro-optic_modulator

https://en.wikipedia.org/wiki/Electronics

https://en.wikipedia.org/wiki/Battery_(electricity)

https://en.wikipedia.org/wiki/Liquid-crystal_display#cite_note-Fujitsu-1

https://en.wikipedia.org/wiki/Image_persistence

https://en.wikipedia.org/wiki/Screen_burn-in

https://en.wikipedia.org/wiki/Plasma_display

https://en.wikipedia.org/wiki/Cathode_ray_tube

https://en.wikipedia.org/wiki/Telephone

https://en.wikipedia.org/wiki/Calculator

https://en.wikipedia.org/wiki/Watch

https://en.wikipedia.org/wiki/Clock

https://en.wikipedia.org/wiki/Flight_instruments

https://en.wikipedia.org/wiki/Instrument_panel

https://en.wikipedia.org/wiki/Television

https://en.wikipedia.org/wiki/Computer_monitor

https://en.wikipedia.org/wiki/Pixel

https://en.wikipedia.org/wiki/Digital_clock

https://en.wikipedia.org/wiki/7-segment

https://en.wikipedia.org/wiki/Liquid_Crystals

https://en.wikipedia.org/wiki/Video_display

https://en.wikipedia.org/wiki/Electronic_visual_display

https://en.wikipedia.org/wiki/Flat_panel_display


These components are “specialized” for being used with the microcontrollers,

which means they cannot be activated by standard IC circuits. They are used for writing

different messages on a miniature LCD.

Fig 8: LCD display screen

Advantages Very compact and light.

Low power consumption. Depending on the set display brightness and content being

displayed, the older CCFT backlit models typically use 30–50% of the power a CRT

monitor of the same size viewing area would use, and the modern LED backlit

models typically use 10–25% of the power a CRT monitor would use.

Very little heat emitted during operation, due to low power consumption.

No geometric distortion.

The possible ability to have little or no flicker depending on backlight technology.

Usually no refresh-rate flicker, because the LCD pixels hold their state between

refreshes (which are usually done at 200 Hz or faster, regardless of the input refresh

rate).

Is very thin compared to a CRT monitor, which allows the monitor to be placed

farther back from the user, reducing close-focusing related eye-strain.

Razor sharp image with no bleeding/smearing when operated at native resolution.


https://en.wikipedia.org/wiki/Native_resolution


Features:

Interface with either 4-bit or 8-bit microprocessor.

Display data RAM

80xx8 bits (80 characters).

Character generator ROM

160 different 5x7 dot-matrix character patterns.

Character generator RAM

8 different user programmed 5x7 dot-matrix patterns.

Display data RAM and character generator RAM may be

Accessed by the microprocessor.

Numerous instructions

Clear Display, Cursor Home, Display ON/OFF, Cursor ON/OFF,

Blink Character, Cursor Shift, Display Shift.

Built-in reset circuit is triggered at power ON.

Built-in oscillator.

Description Of 16x2:

This is the first interfacing example for the Parallel Port. We will start with

something simple. This example doesn't use the Bi-directional feature found on

newer ports, thus it should work with most, if no all Parallel Ports. It however

doesn't show the use of the Status Port as an input. So what are we interfacing? A 16

Character x 2 Line LCD Module to the Parallel Port. These LCD Modules are very

common these days, and are quite simple to work with, as all the logic required to

run them is on board



Schematic Diagram:

fig 9:LCD schematic diagram

The 2 line x 16 character LCD modules are available from a wide range of manufacturers and should all be compatible with the HD44780. The one I used to test this circuit was a Power tip PC-1602F and an old Philips LTN211F-10 which was extracted from a Poker Machine! The diagram to the right, shows the pin numbers for these devices. When viewed from the front, the left pin is pin 14 and the right pin is pin 1

16 x 2 Alphanumeric LCD Module Features:

Intelligent, with built-in Hitachi HD44780 compatible LCD controller and RAM

providing simple interfacing

61 x 15.8 mm viewing area

5 x 7 dot matrix format for 2.96 x 5.56 mm characters, plus cursor line

Can display 224 different symbols

Low power consumption (1 mA typical)



Powerful command set and user-produced characters

TTL and CMOS compatible

Connector for standard 0.1-pitch pin headers

Power supply for LCD driving:

Fig 10: power supply for LCD

PIN DESCRIPTION:

Most LCDs with 1 controller has 14 Pins and LCDs with 2 controller has 16 Pins (two pins

are extra in both for back-light LED connections).

Fig 11:pin diagram of 1x16 lines LCD



Table 6: LCD Pin specifications

4.6 CONTROL LINES:

EN:

Line is called "Enable." This control line is used to tell the LCD that you are sending

it data. To send data to the LCD, your program should make sure this line is low (0) and

then set the other two control lines and/or put data on the data bus. When the other lines are

completely ready, bring EN high (1) and wait for the minimum amount of time required by

the LCD datasheet (this varies from LCD to LCD), and end by bringing it low (0) again.

RS:

Line is the "Register Select" line. When RS is low (0), the data is to be treated as a

command or special instruction (such as clear screen, position cursor, etc.). When RS is

high (1), the data being sent is text data which sould be displayed on the screen. For

example, to display the letter "T" on the screen you would set RS high.

RW:

Line is the "Read/Write" control line. When RW is low (0), the information on the

data bus is being written to the LCD. When RW is high (1), the program is effectively



querying (or reading) the LCD. Only one instruction ("Get LCD status") is a read command.

All others are write commands, so RW will almost always be low.

Finally, the data bus consists of 4 or 8 lines (depending on the mode of operation

selected by the user). In the case of an 8-bit data bus, the lines are referred to as DB0, DB1,

DB2, DB3, DB4, DB5, DB6, and DB7.

Logic status on control lines:

E - 0 Access to LCD disabled

1 Access to LCD enabled

R/W - 0 Writing data to LCD

1 Reading data from LCD

RS - 0 Instructions

1 Character

Writing data to the LCD:

Set R/W bit to low

Set RS bit to logic 0 or 1 (instruction or character)

Set data to data lines (if it is writing)

Set E line to high

Set E line to low

Read data from data lines (if it is reading) on LCD:

Set R/W bit to high

Set RS bit to logic 0 or 1 (instruction or character)

Set data to data lines (if it is writing)

Set E line to high

Set E line to low



FLOWCHART:

Fig 12: flow chart of LCD.

4.7 Light Dependent Resistor

A photoresistor or light dependent resistor or cadmium sulfide (CdS) cell is

a resistor whose resistance decreases with increasing incident light intensity. It can also be

referred to as a photoconductor.

A photo resistor is made of a high resistance semiconductor. If light falling on the

device is of high enough frequency, photons absorbed by the semiconductor give

bound electrons enough energy to jump into the conduction band. The resulting free

electron (and its hole partner) conduct electricity, there by lowering resistance.



A photoelectric device can be either intrinsic or extrinsic. An intrinsic

semiconductor has its own charge carriers and is not an efficient semiconductor, e.g. silicon.

In intrinsic devices the only available electrons are in the valence band, and hence the

photon must have enough energy to excite the electron across the entire bandgap. Extrinsic

devices have impurities, also called dopants, added whose ground state energy is closer to

the conduction band; since the electrons do not have as far to jump, lower energy photons

(i.e., longer wavelengths and lower frequencies) are sufficient to trigger the device. If a

sample of silicon has some of its atoms replaced by phosphorus atoms (impurities), there

will be extra electrons

available for conduction. This is an example of an extrinsic semiconductor.

The symbol for a photoresistor

Applications:

Photoresistors come in many different types. Inexpensive cadmium sulfide cells can

be found in many consumer items such as camera light meters, street lights, clock

radios, alarms, and outdoor clocks.

They are also used in some dynamic compressors together with a small incandescent

lamp or light emitting diode to control gain reduction.

Lead sulfide (PbS) and indium antimonide (InSb) LDRs (light dependent resistor)

are used for the mid infrared spectral region. Ge:Cu photoconductors are among the best

far-infrared detectors available, and are used for infrared astronomy and infrared

spectroscopy.

Fig 13: LDR


http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/Copper

http://en.wikipedia.org/wiki/Germanium


A light dependent resistor is a small, round semiconductor. Light dependent resistors

are used to re-charge a light during different changes in the light, or they are made to turn a

light on during certain changes in lights. One of the most common uses for light dependent

resistors is in traffic lights. The light dependent resistor controls a built in heater inside the

traffic light, and causes it to recharge over night so that the light never dies. Other common

places to find light dependent resistors are in: infrared detectors, clocks and security alarms.

LDRs or Light Dependent Resistors are very useful especially in light/dark sensor

circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000

ohms, but when they are illuminated with light resistance drops dramatically.

The animation opposite shows that when the torch is turned on, the resistance of the LDR

falls, allowing current to pass through it.

Circuit Wizard software has been used to display, the range of values of a

ORP12,LDR .

When a light level of 1000 lux (bright light) is directed towards it, the resistanceis

400R(ohms).

When a light level of 10 lux (very low light level) is directed towards it, the resistance has

risen dramatically to 10.43M (10430000 ohms).

Basic structure:

Although there are many ways in which LDR’s or photo resistors can be

manufactured, ther are naturally a few more common methods that are seen. Essentially the

LDR or photo resistor consists of a resistive material sensitive to light that is

exposed to light. The photo resistive element comprises section of material with contacts at

either end. Although many of the material used for light dependent resistors are

semiconductors, when used as photo resistors, they are used only as a resistive element and

there are no p-n junctions. Accordingly the devices purely passive.

Operation:

Light Dependent Resistor made of a high resistance semiconductor, if light falling on

the is of high enough efficiently, photon absorbed by the semiconductor give bound

electrons enough energy to jump into the conduction band. The resulting free electron (and

its hole partner) conduct electricity, thereby lowering resistance.



In intrinsic devices, the only available electrons are in the valence band, and hence

the photon must have enough energy to excite the electrons across the entire band gap.

Extrinsic devices have impurities added , which have a ground state energy closer to the

conduction band, since the electrons don’t have so far to jump, lower energy photons ( i.e.

longer wavelengths and lower frequencies ) will suffice to trigger the device.

Characteristics of LDR:

The characteristics of LDR are shown below. Here the resistance variations are

shown as a function of illumination. The resistance of LDR decreases with increasing

incident light intensity

10

1.0

0.1

0.1 1.0 10 100

( Ftc )*

*1 Ftc = 10.764 lumens

Fig 14: LDR characteristics.

LDR Applications:

LDR’s are very useful especially in light/dark sensor circuits

1. Camera light meters.

2. Clock radios.


1000

100

Res.


CHAPTER 5

SOFTWARE DESCRIPTION

5.1 KEIL µVISION3 Software:

µVISION3 Overview:

The µVision3 IDE is a windows based software development platform that combines

a robust editor, project manager, and integrated make facility. µVision3 integrates all tools

including the C compiler, macro assembler, linker/locator, and HEX file generator.

µVision3 helps expedite the development process of our embedded applications by

providing the following:

Full-featured source code editor.

Device database for configuring the development tool setting.

Project manager for creating and maintaining our projects.

Integrated make facility for assembling, compiling, and linking our embedded

applications.

Dialogs for all development tool settings.

True integrated source level Debugger with high-speed CPU and peripheral

simulator.

Advanced GDI interface for software debugging in the target hardware and for

connection to Keil ULINK.

Flash programming utility for downloading the application program into Flash

ROM.

Links to development tools manuals, device datasheets and user’s guides.

In the Build Mode, we maintain the project files and generate the application. In the

Debug Mode, we verify our program either with a powerful CPU and peripheral simulator

or with the Keil ULINK USB-JTAG Adapter (or other AGDI drivers) that connect the



debugger to the target system. The ULINK allows us also to download our application into

Flash ROM of our target system.

Environment :

The µVision3 screen provides us with a menu bar for command entry, a tool bar where we

can rapidly select command buttons, and windows for source files, dialog boxes, and information

displays. µVision3 lets us simultaneously open and view multiple source files.

µVision3 has two operating modes:

Build Mode:

Allows us to translate all the application files and to generate executable programs. The

features of the Build Mode are described under Creating Applications.

Debug Mode:

Provides us with a powerful debugger for testing our application. The Debug Mode is

described in Testing Programs.

In both operating modes we may use the source editor of µVision3 to modify our source

code. The Debug mode adds additional windows and stores an own screen layout.

Figure 15 : Debug mode command window

The tabs of the Project Workspace give us access to:



Files and Groups of the project.

CPU Registers during debugging.

Tool and project specific on-line Books.

Text Templates for often used text blocks.

Function in the project for quick editor navigation.

The tabs of the Output Window provides: Build messages and fast error access;

Debug Command input/output console; Find in Files results with quick file access.

The Memory Window gives access to the memory areas in display various formats.

The Watch and Call Stack Window allow us to review and modify program variables

and display the current function call tree.

The Workspace is used for the file editing, disassembly output, and other debug

information.

The Peripheral Dialogs help us to review the status of the on-chip.

Software development Lifecycle :

When you use the Keil µVision3, the project development cycle is roughly the same as it is for

any other software development project.

Create a project, select the target chip from the device database, and configure the tool

settings.

Create source files in C or assembly.

Build our application with the project manager.

Correct errors in source files.

Test the linked application.



Create a project:

µVision3 includes a project manager which makes it easy to design applications for

an ARM based microcontroller. We need to perform the following steps to create a new

project:

Create Project file and Select CPU

Project Workspace-Books

Create New Source Files

Add Source Files to the Project

Create Files Groups

Set tool Options for Target Hardware

Configure the CPU Start-up Code

Build Project and Generate Application Program Code

Description:

Add Source Files to Project:

Once we have created our source file we can add this file to our project. µVision3 offers

several ways to add source files to a project. For example, we can select the file group in the

Project Workspace — Files page and click with the right mouse key to open a local menu. The

option Add Files opens the standard files dialog. Select the file MAIN.C we have just created.

Simulation:

The µVision3 Debugger incorporates a C script language you can use to create

Signal Functions. Signal functions let us simulate analog and digital input to the

microcontroller. Signal functions run in the background while µVision3 simulates our target

program.

5.2 Program



#include<reg51.h>

#define lcd_data P2

sbit lcd_rs = P2^0;

sbit lcd_en = P2^1;

sbit rd=P3^2;

sbit wr=P3^3;

sbit intr=P3^4;

void delay(unsigned int t)

{

unsigned int i,j;

for(i=0;i<t;i++)

for(j=0;j<1275;j++);

}

void lcdcmd(unsigned char value) // LCD COMMAND

{

lcd_data=value&(0xf0); //send msb 4 bits

lcd_rs=0; //select command register

lcd_en=1; //enable the lcd to execute command

delay(3);

lcd_en=0;

lcd_data=((value<<4)&(0xf0)); //send lsb 4 bits

lcd_rs=0; //select command register

lcd_en=1; //enable the lcd to execute command

delay(3);

lcd_en=0;

}

void lcd_init(void)



{

lcdcmd(0x02);

lcdcmd(0x02);

lcdcmd(0x28); //intialise the lcd in 4 bit mode*/

lcdcmd(0x28); //intialise the lcd in 4 bit mode*/

lcdcmd(0x0e); //cursor blinking

lcdcmd(0x06); //move the cursor to right side

lcdcmd(0x01); //clear the lcd

}

void lcddata(unsigned char value)

{

lcd_data=value&(0xf0); //send msb 4 bits

lcd_rs=1; //select data register

lcd_en=1; //enable the lcd to execute data

delay(3);

lcd_en=0;

lcd_data=((value<<4)&(0xf0)); //send lsb 4 bits

lcd_rs=1; //select data register

lcd_en=1; //enable the lcd to execute data

delay(3);

lcd_en=0;

delay(3);

}

void msgdisplay(unsigned char b) // send string to lcd

{

unsigned char s,count1=0;

for(s=0;b[s]!='\0';s++)

{



count1++;

if(s==16)

lcdcmd(0xc0);

if(s==32)

{

lcdcmd(1);

count1=0;

}

lcddata(b[s]);

}

}

void main()

{

unsigned char a;

lcd_init();

lcdcmd(0x80);

msgdisplay("ELECTRONIC EYE") ;

delay(400);

lcdcmd(0xc0);

msgdisplay("COLOR:");//0X85

intr=1;

rd=1;

wr=1;

while(1)

{

wr=0;



wr=1;

while(intr==1);

rd=0;

a=P1;

rd=1;

if(a>= && a< )

{

lcdcmd(0xc6);

msgdisplay("");

}

if(a>= && a< )

{

lcdcmd(0xc6);

msgdisplay("");

}

if(a>= && a< )

{

lcdcmd(0xc6);

msgdisplay("");

}

}

}

5.3 Conclusion: By changing the values in the while loop there is a change in the color.The values thus obtained was random and depends on ADC which gives different values for different colours depending on the intensity values of light.



CHAPTER 6

CONCLUSION AND FUTURE SCOPE

6.1 CONCLUSION:

This project presents electronic eye based automation controlling. The controller based on closed loop algorithm is designed and implemented with Atmel MCU in embedded system the domain.

Experimental work has been carried out carefully. with the help of 8052 controller.In all low end applications now a days we are using 8052 controllers like industrial automation and data acquisition.

All the inherent parts of the circuit performed consistently. It helped us to come out with good judgment. With the features what it inherits, it seems to be advantageous to the present era.

6.2 SCOPE OF THE PROJECT:

We can modify this project by replacing LDR sensor with photo camera which is

then image processed for better purpose in future So future scope of this project is ever

lasting and it depends on public need.



CHAPTER 7

RESULT

The outcome of this project was as expected. The different inputs given to the device gave predicted outputs.And siginificantly other than colored objects were also detected. The received data is displayed on the LCD panel. The LCD panel was very impressive with its emitting ability, it displayed the data very precisely.

LDR’s are very useful especially in light/dark sensor circuits. Normally the

resistance of LDR is very high, sometimes as high as 1000k ohms,but when they are

illuminated with light, resistance drops immediately.The following are some of the major

applications.

1. Camera light meters.

2. Clock radios.

3. Security alarms.

4. Optical switches.

5. Far infrared detector.

6. Streetlights.

The future would be completely automated sytems.This project is majorly used in Textile industries for power looms and Robotics in a wide range.This Project is very cheap and accurate automation system .



BIBILOGRAPHY

Books Referred:

Muhammad Ali Mazidi - The 8051 Micro controller and Embedded systems.

B.Ram - Fundamentals of Micro processors and Micro computers.

Ramesh S.Gaonkar- Micro processor Architecture, Programming& Applications.

D.V.Prasad- Electronic components.

Websites Referred:

www.national.com www.atmel.com www.electronicsforu.com www.futurelec.com


Electronic Eye For detecting multi-colors

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