rail way gate

7/29/2019 Rail Way Gate

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CHAPTERI

INTRODUCTION

Now a days, India is the country which having worlds largest railway

network. Over hundreds of railways running on track every day. As railway has

straightway running as well as it has somewhat risky and dangerous as per as

general public and traffic concern. As we know that it is surely impossible to

stop the running train at instant is some critical situation or emergency arises.Therefore at the places of traffic density, suburban areas and crossings there is

severe need to install a railway gate in view of protection purpose. Obviously at

each and every gate there must be a attendant to operate and maintain it.

In view of that, if we calculate the places of railway crossings and suchplaces where it would to be install and overall expenditure, the graph arises and

arises at the extent. But, India, our country is a progressive country. It has

already enough economical problems which are ever been unsolved. So, to

avoid all these things some sort of automatic and independent system comes in

picture. Now a days automatic system occupies each and every sector of

applications as it is reliable, accurate and no need to pay high attention At

present scenario, in level crossings, the railway gate is operated normally by a

gate keeper after receiving the information about the train's arrival.


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When a train starts to leave a station, station master of the particular

station delivers the information to the near by gate. The above said procedures

are followed for operating the railway gates. Semiautomatic railway gate

operation is also followed in certain areas. Signals are located in the vicinity of

the railway gate along with gate master board and a marker light. Our paper

deals with automatic railway gate control (i.e.) gate operated with out gate

keepers. It is implemented in unmanned level crossings at remote areas.


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CHAPTERII

MICROCONTROLLER

2.1 Introduction

Microcontrollers are destined to play an increasingly important role in

revolutionizing various industries and influencing our day to day life more

strongly than one can imagine. Since its emergence in the early 1980's the

microcontroller has been recognized as a general purpose building block for

intelligent digital systems. It is finding using diverse area, starting from simple

children's toys to highly complex spacecraft. Because of its versatility and many

advantages, the application domain has spread in all conceivable directions,

making it ubiquitous. As a consequence, it has generate a great deal of interest

and enthusiasm among students, teachers and practicing engineers, creating an

acute education need for imparting the knowledge of microcontroller based

system design and development. It identifies the vital features responsible for

their tremendous impact, the acute educational need created by them andprovides a glimpse of the major application area.

A microcontroller is a complete microprocessor system built on a single

IC. Microcontrollers were developed to meet a need for microprocessors to be

put into low cost products. Building a complete microprocessor system on a

single chip substantially reduces the cost of building simple products, which use

the microprocessor's power to implement their function, because the

microprocessor is a natural way to implement many products.


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This means the idea of using a microprocessor for low cost products

comes up often. But the typical 8-bit microprocessor based system, such as one

using a Z80 and 8085 is expensive. Both 8085 and Z80 system need some

additional circuits to make a microprocessor system. Each part carries costs of

money. Even though a product design may require only very simple system, the

parts needed to make this system as a low cost product. To solve this problem

microprocessor system is implemented with a single chip microcontroller. This

could be called microcomputer, as all the major parts are in the IC. Most

frequently they are called microcontroller because they are used they are used

to perform control functions. The microcontroller contains full implementation

of a standard MICROPROCESSOR, ROM, RAM, I/0, CLOCK, TIMERS, and

also SERIAL PORTS. Microcontroller also called "system on a chip" or "single

chip microprocessor system" or "computer on a chip".

A microcontroller is a Computer-On-A-Chip, or, if you prefer, a single-

chip computer. Micro suggests that the device is small, and controller tells youthat the device' might be used to control objects, processes, or events. Another

term to describe a microcontroller is embedded controller, because the

microcontroller and its support circuits are often built into, or embedded in, the

devices they control. Today microcontrollers are very commonly used in wide

variety of intelligent products. For example most personal computers keyboards

and implemented with a microcontroller. It replaces Scanning, Debounce,

Matrix Decoding, and Serial transmission circuits. Many low cost products,

such as Toys, Electric Drills, Microwave Ovens, VCR and a host of other

consumer and industrial products are based on microcontrollers.


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BLOCK AND PIN DIAGRAM OF MICROCONTROLLER


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2.2 PIN Description

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port. As an output port each

pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can

be used as high impedance inputs. Port 0 may also be configured to be the

multiplexed low order address/data bus during accesses to external 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 bidirectional 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. 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 Flash programming and verification.

Port 2





because of the internal pull-ups. Port 2 emits the high-order address byte during

fetches from external program memory and during accesses to external data

memory that use 16-bit addresses (MOVX @ DPTR). In this application it uses

strong internal pull-ups when emitting 1s.


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Port 3





because of the pull-ups. Port 3 also serves the functions of various special

features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and

verification.

RSTReset input. A high on this pin for two machine cycles while the

oscillator 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 is also the program pulse

input (PROG) during Flash programming. In normal operation ALE is emitted

at a constant rate of 1/6 the oscillator frequency, and may be used for external

timing or clocking purposes. Note, however, that one ALE pulse is skipped

during each access to external Data Memory.


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If desired, ALE operation can be disabled by setting bit 0 of SFR location

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

instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable

bit has no effect if the microcontroller is in external execution mode.

PSEN

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

When the AT89C51 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. 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 require 12-volt VPP.

XTAL1

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

operating circuit.

XTAL2

Output from the inverting oscillator amplifier. It should be noted that

when idle is terminated by a hard ware reset, the device normally resumes

program execution, from where it left off, up to two machine cycles before the

internal reset algorithm takes control. On-chip hardware inhibits access to

internal RAM in this event, but access to the port pins is not inhibited.


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ARCHITECTURE OF 89C51


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2.3 Advantages of Microcontrollers:

1. If a system is developed with a microprocessor, the designer has togo for external memory such as RAM, ROM or EPROM and peripherals and

hence the size of the PCB will be large enough to hold all the required

peripherals. But, the micro controller has got all these peripheral facilities on a

single chip so development of a similar system with a micro controller reduces

PCB size and cost of the design.

One of the major differences between a micro controller and a

microprocessor is that a controller often deals with bits , not bytes as in the real

world application, for example switch contacts can only be open or close,

indicators should be lit or dark and motors can be either turned on or off and so

forth.


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CHAPTERIII

COMPONENTS OF UNMANNED RAIL WAY

CROSSING

3.1 INTRODUCTION

This project is designed by following blocks,

Microcontroller Relays DC motor Gate model Proximity sensor

3.2 ATMEL MICROCONTROLLER

SERIES: 89C51 Family

TECHNOLOGY: CMOS

Features ATMEL 89C51:

8 Bit CPU optimized for control applicationsOn - Chip Flash Program MemoryOn - Chip Data RAMBi-directional and Individually Addressable I/O LinesMultiple 16-Bit Timer/CountersFull Duplex UART


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Multiple Source / Vector / Priority Interrupt StructureOn - Chip Oscillator and Clock circuitry.On - Chip EEPROMSPI Serial Bus InterfaceWatch Dog Timer

POWER MODES

To exploit the power savings available in CMOS circuitry. Atmels Flash

micro controllers have two software-invited reduced power modes.

IDLE MODE:

The CPU is turned off while the RAM and other on - chip peripherals

continue operating. Inn this mode current draw is reduced to about 15 percent

of the current drawn when the device is fully active.

POWER DOWN MODE:

All on-chip activities are suspended while the on chip RAM continuesto hold its data. In this mode, the device typically draws less than 15 Micro

Amps and can be as low as 0.6 Micro Amps

POWER ON RESET:

When power is turned on, the circuit holds the RST pin high for an

amount of time that depends on the capacitor value and the rate at which it

charges. To ensure a valid reset, the RST pin must be held high long enough to

allow the oscillator to start up plus two machine cycles. On power up, VCC

should rise within approximately 10ms. The oscillator start-up time depends on

the oscillator frequency. For a 10 MHz crystal, the start-up time is typically

1ms.


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MEMORY ORGANIZATION:

* Logical Separation of Program and Data Memory *

All Atmel Flash micro controllers have separate address spaces for

program and data memory as shown in Fig 1.The logical separation of

program and data memory allows the data memory to be accessed by 8 bit

addresses. This can be more quickly stored and manipulated by an 8 bit CPU

Nevertheless 16 Bit data memory addresses can also be generated through the

DPTR register.

Program memory can only be read. There can be up to 64K bytes of

directly addressable program memory. The read strobe for external program

memory is the Program Store Enable Signal (PSEN) Data memory occupies a

separate address space from program memory. Up to 64K bytes of external

memory can be directly addressed in the external data memory space. The CPU

generates read and write signals, RD and WR, during external data memory

accesses. External program memory and external data memory can be

combined by an applying the RD and PSEN signals to the inputs of AND gate

and using the output of the fate as the read strobe to the external program/data

memory.

PROGRAM MEMORY:

The map of the lower part of the program memory, after reset, the CPU

begins execution from location 0000h. Each interrupt is assigned a fixed

location in program memory. The interrupt causes the CPU to jump to that

location, where it executes the service routine. External Interrupt 0 for example,

is assigned to location 0003h.


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The interrupt service locations are spaced at 8 byte intervals 0003h for

External interrupt 0, 000Bh for Timer 0, 0013h for External interrupt 1,001Bh

for Timer1, and so on. If an Interrupt service routine is short enough (as is often

the case in control applications) it can reside entirely within that 8-byte interval.

Longer service routines can use a jump instruction to skip over subsequent

interrupt locations. If other interrupts are in use.

The lowest addresses of program memory can be either in the on-chip

Flash or in an external memory. To make this selection, strap the External

Access (EA) pin to either VCC or GND. For example, in the AT89C51 with 4K

bytes of on-chip Flash, if the EA pin is strapped to VCC, program fetches to

addresses 0000h through 0FFFh are directed to internal Flash. Program fetches

to addresses 1000h through FFFFh are directed to external memory.

DATA MEMORY:

The Internal Data memory is dived into three blocks namely, Refer Fig

The lower 128 Bytes of Internal RAM. The Upper 128 Bytes of Internal RAM. Special Function Register

Internal Data memory Addresses are always 1 byte wide, which implies

an address space of only 256 bytes. However, the addressing modes for internal

RAM can in fact accommodate 384 bytes. Direct addresses higher than 7Fh

access one memory space, and indirect addresses higher than 7Fh access a

different Memory Space. The lowest 32 bytes are grouped into 4 banks of 8

registers.


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Program instructions call out these registers as R0 through R7. Two bits

in the Program Status Word (PSW) Select, which register bank, is in use. This

architecture allows more efficient use of code space, since register instructions

are shorter than instructions that use direct addressing. The next 16-bytes above

the register banks form a block of bit addressable memory space. The micro

controller instruction set includes a wide selection of single - bit instructions

and this instruction can directly address the 128 bytes in this area. These bit

addresses are 00h through 7Fh. either direct or indirect addressing can access all

of the bytes in lower 128 bytes. Indirect addressing can only access the upper

128. The upper 128 bytes of RAM are only in the devices with 256 bytes of

RAM.

The Special Function Register includes Ports latches, timers, peripheral

controls etc., direct addressing can only access these register. In general, all

Atmel micro controllers have the same SFRs at the same addresses in SFR

space as the AT89C51 and other compatible micro controllers. However,

upgrades to the AT89C51 have additional SFRs. Sixteen addresses in SFR

space are both byte and bit Addressable. The bit Addressable SFRs are those

whose address ends in 000B. The bit addresses in this area are 80h through

FFh.


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ADDRESSING MODES:

DIRECT ADDRESSING:

In direct addressing, the operand specified by an 8-bit address field in the

instruction. Only internal data RAM and SFRs can be directly addressed.

INDIRECT ADDRESSING:

In Indirect addressing, the instruction specifies a register that contains the

address of the operand. Both internal and external RAM can indirectly address.

The address register for 8-bit addresses can be either the Stack Pointer or R0 or

R1 of the selected register Bank. The address register for 16-bit addresses can

be only the 16-bit data pointer register, DPTR.

INDEXED ADDRESSING:

Program memory can only be accessed via indexed addressing this

addressing mode is intended for reading look-up tables in program memory. A

16 bit base register (Either DPTR or the Program Counter) points to the base of

the table, and the accumulator is set up with the table entry number. Adding the

Accumulator data to the base pointer forms the address of the table entry in

program memory. Another type of indexed addressing is used in the case jump

instructions. In this case the destination address of a jump instruction is

computed as the sum of the base pointer and the Accumulator data.


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REGISTER INSTRUCTION:

The register banks, which contains registers R0 through R7, can be

accessed by instructions whose opcodes carry a 3-bit register specification.

Instructions that access the registers this way make efficient use of code, since

this mode eliminates an address byte. When the instruction is executed, one of

four banks is selected at execution time by the row bank select bits in PSW.

IMMEDIATE CONSTANTS:

The value of a constant can follow the opcode in program memory For

example. MOV A, #100 loads the Accumulator with the decimal number 100.

The same number could be specified in hex digit as 64h.

PROGRAM STATUS WORD:

rogram Status Word Register in Atmel Flash Micro controller:

CY AC F0 RS1 RS0 OV --- P

PSW 7 PSW 0

PSW 6 PSW 1

PSW 5 PSW 2

PSW 4 PSW 3

PSW 0:

Parity of Accumulator Set By Hardware To 1 if it contains an Odd

number of 1s, Otherwise it is reset to 0.


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PSW1:

User Definable Flag

PSW2:

Overflow Flag Set By Arithmetic Operations

PSW3:

Register Bank Select

PSW4:

Register Bank Select

PSW5:

General Purpose Flag.

PSW6:

Auxiliary Carry Flag Receives Carry Out from

Bit 1 of Addition Operands

PSW7:

Carry Flag Receives Carry Out From Bit 1 of ALU Operands.

The Program Status Word contains Status bits that reflect the current sate

of the CPU. The PSW shown if Fig resides in SFR space. The PSW contains the

Carry Bit, The auxiliary Carry (For BCD Operations) the two - register bank

select bits, the Overflow flag, a Parity bit and two user Definable status Flags.

The Carry Bit, in addition to serving as a Carry bit in arithmetic

operations also serves the as the Accumulator for a number of Boolean

Operations .The bits RS0 and RS1 select one of the four register banks. A

number of instructions register to these RAM locations as R0 through

R7.The status of the RS0 and RS1 bits at execution time determines

which of the four banks is selected.


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The Parity bit reflect the Number of 1s in the Accumulator .P=1 if the

Accumulator contains an even number of 1s, and P=0 if the Accumulator

contains an even number of 1s. Thus, the number of 1s in the Accumulator plus

P is always even. Two bits in the PSW are uncommitted and can be used as

general-purpose status flags.

INTERRUPTS

The AT89C51 provides 5 interrupt sources: Two External interrupts,

two-timer interrupts and a serial port interrupts. The External Interrupts INT0

and INT1 can each either level activated or transistion - activated, depending on

bits IT0 and IT1 in Register TCON. The Flags that actually generate these

interrupts are the IE0 and IE1 bits in TCON. When the service routine is

vectored to hardware clears the flag that generated an external interrupt only if

the interrupt WA transition - activated. If the interrupt was level - activated,

then the external requesting source (rather than the on-chip hardware) controls

the requested flag. Tf0 and Tf1 generate the Timer 0 and Timer 1 Interrupts,

which are set by a rollover in their respective Timer/Counter Register (except

for Timer 0 in Mode 3).

When a timer interrupt is generated, the on-chip hardware clears the flag

that generated it when the service routine is vectored to. The logical OR of RI

and TI generate the Serial Port Interrupt. Neither of these flag is cleared by

hardware when the service routine is vectored to. In fact, the service routine

normally must determine whether RI or TI generated the interrupt an the bit

must be cleared in software. In the Serial Port Interrupt is generated by the

logical OR of RI and TI.


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IE: INTERRUPT ENABLE REGISTER

EA - ET2 ES ET1 EX1 ET0 EX0

Enable bit = 1 enabled the interrupt

Enable bit = 0 disables it.

Symbol Position Function

EA IE

Global enable / disable all interrupts. If EA = 0, no

interrupt will be Acknowledge. If EA = 1, each

interrupt source is individually enabled to disabledby

setting or clearing its enable bit

ET2 IE.5 Timer 2 Interrupt enable Bit

ES IE.4 Serial Port Interrupt enabled bit

ET1 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.

OSCILLATOR AND CLOCK CIRCUIT:

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

amplifier which is intended for use as a crystal oscillator in the pierce

configuration, in the frequency range of 1.2 MHz to 12 MHz. XTAL2 also the

input to the internal clock generator. To drive the chip with an internal

oscillator, one would ground XTAL1 and XTAL2.


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Since the input to the clock generator is divide by two flip flop there are

no requirements on the duty cycle of the external oscillator signal. However,

minimum high and low times must be observed. The clock generator divides the

oscillator frequency by 2 and provides a tow phase clock signal to the chip. The

phase 1 signal is active during the first half to each clock period and the phase 2

signals are active during the second half of each clock period.

CPU TIMING:

A machine cycle consists of 6 states. Each stare is divided into a phase /

half, during which the phase 1 clock is active and phase 2 half. Arithmetic and

Logical operations take place during phase1 and internal register - to register

transfer take place during phase 2

TRENDS AND DEVELOPMENTS IN MICRO CONTROLLER

The manner in which the use of micro controllers is shaping our lives is

breathtaking. Today, this versatile device can be found in a variety of control

applications. CVTs, VCRs, CD players, microwave ovens, and automotive

engine systems are some of these. A micro controller unit (MCU) uses the

microprocessor as its central processing unit (CPU) and incorporates memory,

timing reference, I/O peripherals, etc on the same chip. Limited computational

capabilities and enhanced I/O are special features. The micro controller is the

most essential IC for continuous process- based applications in industries like

chemical, refinery, pharmaceutical automobile, steel, and electrical, employing

programmable logic systems (DCS). PLC and DCS thrive on the

programmability of an MCU. There are many MCU manufacturers. To

understand and apply general concepts, it is necessary to study one type in

detail.


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This specific knowledge can be used to understand similar features of

otherMCUs. Micro controller devices have many similarities. When you look

at the differences, they are not so great either. Most common and popular

MCUs are considered to be mature and well-established products, which have

their individual adherents and devotees. There are a number of variants within

each family to satisfy most memory, I/O, data conversion, and timing needs of

end-user applications.

The MCU is designed to operate on application-oriented sensor data-for

example, temperature and pressure of a blast furnace in an industrial process

that is fed through its serial or operated on under the control of software and

stored in ROM. Appropriate signals are fed via output ports to control external

devices and systems.


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APPLICATION

Microcontrollers are designed for use in sophisticated real time

applications such as

1. Industrial Control2. Instrumentation and3. Intelligent computer peripherals

They are used in industrial applications to control

Motor Robotics Discrete and continuous process control In missile guidance and control In medical instrumentation Oscilloscopes Telecommunication Automobiles For Scanning a keyboard Driving an LCD

For Frequency measurements

Period Measurements


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3.3 POWER SUPPLY

The ac voltage, typically 220V rms, is connected to a transformer, which

steps that ac voltage down to the level of the desired dc output. A diode rectifier

then provides a full-wave rectified voltage that is initially filtered by a simple

capacitor filter to produce a dc voltage. This resulting dc voltage usually has

some ripple or ac voltage variation. A regulator circuit removes the ripples and

also remains the same dc value even if the input dc voltage varies, or the load

connected to the output dc voltage changes. This voltage regulation is usually

obtained using one of the popular voltage regulator IC units.

Figure: Block diagram (Power supply)

Transformer

The potential transformer will step down the power supply voltage (0-

230V) to (0-6V) level. Then the secondary of the potential transformer will be

connected to the precision rectifier, which is constructed with the help of op

amp. The advantages of using precision rectifier are it will give peak voltage

output as DC, rest of the circuits will give only RMS output.

TRANSFORMER RECTIFIER FILTER IC REGULATOR LOAD


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Bridge rectifier

When four diodes are connected as shown in figure, the circuit is called

as bridge rectifier. The input to the circuit is applied to the diagonally opposite

corners of the network, and the output is taken from the remaining two corners.

Let us assume that the transformer is working properly and there is a positive

potential, at point A and a negative potential at point B. the positive potential at

point A will forward bias D3 and reverse bias D4. The negative potential at

point B will forward bias D1 and reverse D2. At this time D3 and D1 are

forward biased and will allow current flow to pass through them; D4 and D2 are

reverse biased and will block current flow.

The path for current flow is from point B through D1, up through RL,

through D3, through the secondary of the transformer back to point B. this path

is indicated by the solid arrows. Waveforms (1) and (2) can be observed across

D1 and D3. One-half cycle later the polarity across the secondary of the

transformer reverse, forward biasing D2 and D4 and reverse biasing D1 and D3.

Current flow will now be from point A through D4, up through RL, through D2,

through the secondary of T1, and back to point A. This path is indicated by the

broken arrows. Waveforms (3) and (4) can be observed across D2 and D4.

The current flow through RL is always in the same direction. In flowing

through RL this current develops a voltage corresponding to that shown

waveform (5). Since current flows through the load (RL) during both half

cycles of the applied voltage, this bridge rectifier is a full-wave rectifier. One

advantage of a bridge rectifier over a conventional full-wave rectifier is that

with a given transformer the bridge rectifier produces a voltage output that is

nearly twice that of the conventional full-wave circuit.


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IC voltage regulators

Voltage regulators comprise a class of widely used ICs. Regulator IC

units contain the circuitry for reference source, comparator amplifier, control

device, and overload protection all in a single IC. IC units provide regulation of

either a fixed positive voltage, a fixed negative voltage, or an adjustably set

voltage. The regulators can be selected for operation with load currents from

hundreds of milli amperes to tens of amperes, corresponding to power ratings

from milli watts to tens of watts.

A fixed three-terminal voltage regulator has an unregulated dc input

voltage, Vi, applied to one input terminal, a regulated dc output voltage, Vo,

from a second terminal, with the third terminal connected to ground. The series

78 regulators provide fixed positive regulated voltages from 5 to 24 volts.

Similarly, the series 79 regulators provide fixed negative regulated voltages

from 5 to 24 volts.

For ICs, microcontroller, LCD --------- 5 volts For alarm circuit, op-amp, relay circuits ---------- 12 volts


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IC PARTOUTPUT

VOLTAGEMINIMUM VOLT

7805 +5 7.3

7806 +6 8.3

7808 +8 10.5

7810 +10 12.5

7812 +12 14.6

7815 +15 17.7

7818 +18 21.0

7824 +24 27.1Table: Positive Voltage Regulators in 7800 series

3.4 RELAY

A relay is an electrically operated switch. Current flowing through the

coil of the relay creates a magnetic field which attracts a lever and changes the

switch contacts. The coil current can be on or off so relays have two switch

positions and they are double throw (changeover) switches. Relays allow one

circuit to switch a second circuit which can be completely separate from the

first. the link is magnetic and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for a

12V relay, but it can be as much as 100mA for relays designed to operate from

lower voltages. Most ICs (chips) cannot provide this current and a transistor is

usually used to amplify the small IC current to the larger value required for the

relay coil.


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The maximum output current for the popular 555 timer IC is 200mA so

these devices can supply relay coils directly without amplification. Relays

are usually SPDT or DPDT but they can have many more sets of switch

contacts, for example relays with 4 sets of changeover contacts are readily

available. Most relays are designed for PCB mounting but you can solder wires

directly to the pins providing you take care to avoid melting the plastic case of

the relay. The animated picture shows a working relay with its coil and switch

contacts. You can see a lever on the left being attracted by magnetism when the

coil is switched on. This lever moves the switch contacts. There is one set of

contacts (SPDT) in the foreground and another behind them, making the relay

DPDT.

Fig 3.1 Relay


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The relay's switch connections are usually labeled COM, NC and NO:

COM = Common, always connect to this, it is the moving part of theswitch.

NC = Normally Closed, COM is connected to this when the relay coil isoff.

NO = Normally Open, COM is connected to this when the relay coil ison.

This circuit is designed to control the load. The load may be motor or

any other load. The load is turned ON and OFF through relay. The relay ONand OFF is controlled by the pair of switching transistors (BC 547). The relay is

connected in the Q2 transistor collector terminal. A Relay is nothing but

electromagnetic switching device which consists of three pins. They are

Common, Normally close (NC) and Normally open (NO).

The relay common pin is connected to supply voltage. The normally

open (NO) pin connected to load. When high pulse signal is given to base of the

Q1 transistors, the transistor is conducting and shorts the collector and emitter

terminal and zero signals is given to base of the Q2 transistor. So the relay is

turned OFF state. When low pulse is given to base of transistor Q1 transistor,

the transistor is turned OFF. Now 12v is given to base of Q2 transistor so the

transistor is conducting and relay is turned ON. Hence the common terminal

and NO terminal of relay are shorted. Now load gets the supply voltage throughrelay.


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Voltage Signal from Transistor Q1 Transistor Q2

Relay

Microcontroller or PC

1 on off off

0 off on on

3.5 DC MOTOR

A machine that converts direct current power into mechanical power is

known as D.C Motor in fig 3.2. Its generation is based on the principle that

when a current carrying conductor is placed in a magnetic field, the conductor

experiences a mechanical force. The direction of this force is given by

Flemings left hand rule.

Fig 3.2 DC motor.


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WORKING OF A DC MOTOR

Consider a part of a multi polar dc motor as shown in fig. when the

terminals of the motor are connected to an external source of dc supply;

(i) The field magnets are excited developing alternate N and S poles.(ii) The armature conductors carry currents. All conductors under N-pole

carry currents in one direction while all the conductors under S-pole

carry currents in the opposite direction.

Suppose the conductors under N-pole carry currents into the plane of

paper and those under S-pole carry current out of the plane of paper as

shown in fig 3.3. Since each armature conductor is carrying current and is

placed in the magnetic field, mechanical force acts on it. Applying

Flemings left hand rule, it is clear that force on each conductor is tending to

rotate the armature in anticlockwise direction. All these forces add together

to produce a driving torque which sets the armature rotating. When the

conductor moves from one side of the brush to the other, current in the

conductor is received and at the same time it comes under the influence of

next pole which is of opposite polarity. Consequently the direction of force

on the conductor remains same.


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Fig 3.3 Working of DC motor.

PRINCIPLES OF OPERATION

In any electric motor, operation is based on simple electromagnetism. A

current-carrying conductor generates a magnetic field; when this is then placed

in an external magnetic field, it will experience a force proportional to the

current in the conductor, and to the strength of the external magnetic field. As

you are well aware of from playing with magnets as a kid, opposite (North and

South) polarities attract, while like polarities (North and North, South and

South) repel. The internal configuration of a DC motor is designed to harness

the magnetic interaction between a current-carrying conductor and an external

magnetic field to generate rotational motion. Let's start by looking at a simple

2-pole DC electric motor (here red represents a magnet or winding with a

"North" polarization, while green represents a magnet or winding with a

"South" polarization).


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Fig 3. 4 Layout of DC motor. Fig 3.5 3 pole DC motor.

Every DC motor has six basic parts -- axle, rotor (armature), stator,

commutator, field magnet(s), and brushes. In most common DC motors, the

external magnetic field is produced by high-strength permanent magnets. The

stator is the stationary part of the motor -- this includes the motor casing, as

well as two or more permanent magnet pole pieces. The rotor (together with the

axle and attached commutator) rotate with respect to the stator. The rotor

consists of windings (generally on a core), the windings being electrically

connected to the commutator. The above fig 3.4 shows a common motor layout

-- with the rotor inside the stator (field) magnets.

The geometry of the brushes, commutator contacts, and rotor windings

are such that when power is applied, the polarities of the energized winding andthe stator magnet(s) are misaligned, and the rotor will rotate until it is almost

aligned with the stator's field magnets. As the rotor reaches alignment, the

brushes move to the next commutator contacts, and energize the next winding.


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Given our example two-pole motor, the rotation reverses the direction of

current through the rotor winding, leading to a "flip" of the rotor's magnetic

field, driving it to continue rotating. In real life, though, DC motors will always

have more than two poles (three is a very common number). In particular, this

avoids "dead spots" in the commutator. You can imagine how with our example

two-pole motor, if the rotor is exactly at the middle of its rotation (perfectly

aligned with the field magnets), it will get "stuck" there. Meanwhile, with a

two-pole motor, there is a moment where the commutator shorts out the power

supply. This would be bad for the power supply, waste energy, and damage

motor components as well. Yet another disadvantage of such a simple motor is

that it would exhibit a high amount of torque "ripple" (the amount of torque it

could produce is cyclic with the position of the rotor). So since most small DC

motors are of a three-pole design is shown in fig 3.5.

A few things from this namely, one pole is fully energized at a time (but

two others are "partially" energized). As each brush transitions from one

commutator contact to the next, one coil's field will rapidly collapse, as the next

coil's field will rapidly charge up (this occurs within a few microsecond). We'll

see more about the effects of this later, but in the meantime you can see that this

is a direct result of the coil windings' series wiring. There's probably no better

way to see how an average DC motor is put together, than by just opening one

up. Unfortunately this is tedious work, as well as requiring the destruction of a

perfectly good motor. The guts of a disassembled Mabuchi FF-030-PN motor

(the same model that Solar botics sells) are available for (on 10 lines / cm graph

paper). This is a basic 3-pole DC motor, with 2 brushes and three commutator

contacts. The use of an iron core armature (as in the Mabuchi, above) is quite

common, and has a number of advantages.


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First off, the iron core provides a strong, rigid support for the windings a

particularly important consideration for high-torque motors. The core also

conducts heat away from the rotor windings, allowing the motor to be driven

harder than might otherwise be the case. Iron core construction is also relatively

inexpensive compared with other construction types. But iron core construction

also has several disadvantages. The iron armature has a relatively high inertia

which limits motor acceleration. This construction also results in high winding

inductances which limit brush and commutator life. In small motors, an

alternative design is often used which features a 'coreless' armature winding.

This design depends upon the coil wire itself for structural integrity.

As a result, the armature is hollow, and the permanent magnet can be

mounted inside the rotor coil. Coreless DC motors have much lower armature

inductance than iron-core motors of comparable size, extending brush and

commutator life. The coreless design also allows manufacturers to build smaller

motors; meanwhile, due to the lack of iron in their rotors, coreless motors are

somewhat prone to overheating. As a result, this design is generally used just in

small, low-power motors. Beamers will most often see coreless DC motors in

the form of pager motors. Again, disassembling a coreless motor can be

instructive in this case, my hapless victim was a cheap pager vibrator motor.

The guts of this disassembled motor are available (on 10 lines / cm graph

paper). This is (or more accurately, was) a 3-pole coreless DC motor. We never

aim at achieving maximum power due to the following reasons.


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The armature current under this condition is very large much excess of

rated current of the machine. Half of the input power is wasted in the armature

circuit. In fact, if we take into account other losses (iron and mechanical); the

efficiency will be well below 50%. The design specification of the DC motor is

shown in fig 3.6.

Fig 3.6 DC motor.


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3.6 PROXIMITY SENSOR

A proximity sensor, in particular a proximity switch is described. A

component that pertains to a system variable and is independent from the

material of a trigger or target is elected and transformed into a non-periodic

signal that depends upon the distance of the trigger. The trigger of a proximity

sensor can thus be exchanged randomly without requiring subsequent

adjustments.

The impedance of an oscillation circuit which pertains to the proximity

sensor, the impedance of an oscillation circuit coil, the amplitude of the

oscillation circuit signal or a voltage divider ratio between the oscillation circuit

and the additional resistance can be used s system variables for instance. A

proximity sensor for determining an approaching direction of an object is

provided. Relative detection sensitivity is established in a first detection unit

and a second detection unit such that a detection level of the first detection unit

is greater than a detection level of the second detection unit .


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When the object approaches from a first electrode in a direction of

arranging the first electrode and a second electrode, and that the detection level

of the second detection unit is greater than the first detection unit when the

object approaches from a direction perpendicular to the direction of arranging

the first electrode and the second electrode. A proximity position determining

section is adapted to determine the approaching direction of the object based on

the detection level of the first detection unit and the detection level of the

second detection unit. As noted above, it is desired to provide a proximity

sensor capable of determining an approaching direction of an object.A

characteristic feature of the present invention lies in a proximity sensor for

detecting approach of an object based on capacitance, including:an electrode

section including a first electrode and a second electrode arranged adjacent to

each other;

A detecting section including a first detection unit for detecting approach

of the object based on variations in capacitance of the first electrode, and a

second detection unit for detecting approach of the object based on variations in

capacitance of the second electrode, wherein relative detection sensitivity is

established in the first detection unit and the second detection unit such that a

detection level of the first detection unit is greater than a detection level of the

second detection unit when the object approaches from the first electrode in a

direction of arranging the first electrode and the second electrode, and that the

detection level of the second detection unit is greater than the first detection unit

when the object approaches from a direction perpendicular to the direction of

arranging the first electrode and the second electrode.


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A proximity position determining section for determining the

approaching direction of the object based on the detection level of the first

detection unit and the detection level of the second detection unit. With this

arrangement, the proximity position determining section is provided for

establishing the relative detection sensitivity for the first unit having the first

electrode and the second unit having the second electrode to determine the

position of the object based on the detection levels from the first unit and

second unit. This makes it possible to determine the approaching direction of

the object based on the determination results received from the proximity

position determining section without providing the shield and the like. As a

result, the proximity sensor capable of determining the approaching direction of

the object can be easily achieved.

In the proximity sensor of the present invention, the relative detection

sensitivity may be established by determining detection performance of the first

detection unit and the second detection unit or by determining configurations of

the first electrode and the second electrode. With such an arrangement, the

relative sensitivity is achieved in response to the mode of use or the condition in

use by establishing the detection sensitivity by the first detection unit and the

second detection unit, or by determining the configurations of the first electrode

and the second electrode, or by the combination thereof.

The proximity sensor of the present invention may further comprise a

belt-like ground electrode provided in the electrode section and having a

longitudinal section extending along a peripheral direction of a tubular

substrate, wherein the belt-like first electrode and second electrode are arranged

on the substrate along the peripheral direction with the ground electrode

between them and parallel with the ground electrode.


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With this arrangement, it is possible to form the first electrode, the

ground electrode and the second electrode on the tubular substrate in the

mentioned order. For example, it makes it possible not only to facilitate

fabrication of the sensor compared with the arrangement in which an electrode

and an insulating material are layered but also to align the arranging direction of

the first electrode and the second electrode with an axial direction of the tubular

substrate. As a result, it is possible to distinguish between the approach of the

object from a direction along the axial direction and the approach of the object

from a direction perpendicular to the axial direction.

Further, a characteristic feature of a rotational operation detecting device

of the present invention having a rotation detecting section for detecting a

rotational operation of a rotationally-operable knob about an axis, the rotational

operation detecting device comprising:

A first electrode arranged inside the knob at a distal end of the axis in a

direction along the axis;a second electrode arranged inside the knob at a

proximal end of the axis in a direction along the axis.A detection section

including a first detection unit for detecting approach of an object based on

variations in capacitance of the first electrode and a second detection unit for

detecting approach of the object based on variations in capacitance of the

second electrode, wherein relative detection sensitivity is established such that a

detection level of the first detection unit is greater than a detection level of the

second detection unit when the object approaches from the first electrode in a

direction along the axis and that the detection level of the second detection unit

is greater than the first detection unit when the object approaches from a

direction perpendicular to the direction along the axis;


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A proximity position determining section for determining the

approaching direction of the object based on the detection level of the first

detection unit and the detection level of the second detection unit; and an output

control section for allowing output of signals from the rotation detection section

only when a rotational operation is detected in the rotation detection section

when the proximity position determining section detects approach of the object

from the direction perpendicular to the axis. With this arrangement, the

detection level of the first detection unit becomes higher than the detection level

of the second detection unit when the object approaches from the distal end

along the axis of the knob.

On the other hand, the detection level of the second detection unit

becomes higher than the detection level of the first detection unit when the

object approaches from the direction perpendicular to the axis of the knob. The

proximity position determining section is adapted to recognize the difference in

detection level, thereby distinguishing between the state where the user pinches

or grips the knob to rotate the knob and the sate the sleeve of the user\'s clothing

or part of the user\'s body contacts an end portion of the knob to rotate the knob.

The output control section allows output of signals from the rotation detection

section only when it can be determined that the user intentionally has operated

the knob based on the determination results from the proximity position

determining section.

As a result, the rotational operation detecting device is capable of

disregarding operations executed unintentionally by the user and extracting only

the amount of rotation resulting from proper operations.


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Still further, the rotational operation detecting device of the present

invention may comprise a sheet-like substrate that is flexibly

deformable,wherein a belt-like ground electrode is formed on the substrate in a

predetermined direction, the belt-like first electrode and second electrode being

formed on the substrate with the ground electrode between them and parallel

with the ground electrode, and wherein the substrate has a tubular shape to be

fitted into the interior of the knob, on which the belt-like ground electrode as

well as the belt-like first electrode and second electrode are arranged in a

peripheral direction centering the axis. With such an arrangement, since the

sheet-like substrate with the electrodes being formed thereon has a tubular

shape to be fitted into the interior of the knob, it is not required to form the

electrode directly in the interior of the knob. As a result, the capacitance-type

sensor may be easily fabricated.

PCB DESIGN:

Design and Fabrication of Printed circuit boards are explained below.

Printed circuit boards, or PCBs, form the core of electronic equipment domestic

and industrial. Some of the areas where PCBs are intensively used are

computers, process control, telecommunications and instrumentation.

MANUFATCURING:

The manufacturing process consists of two methods; print and etch, and

print, plate and etch. The single sided PCBs are usually made using the print

and etch method. The double sided plate throughhole (PTH) boards are made

by the print plate and etch method. The production of multi layer boards uses

both the methods. The inner layers are printed and etch while the outer layers

are produced by print, plate and etch after pressing the inner layers.


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SOFTWARE:

The software used in our project to obtain the schematic layout is

MICROSIM.

PANELISATION

Here the schematic transformed in to the working positive/negative films.

The circuit is repeated conveniently to accommodate economically as many

circuits as possible in a panel, which can be operated in every sequence of

subsequent steps in the PCB process. This is called penalization. For the PTH

boards, the next operation is drilling.

DRILLING

PCB drilling is a state of the art operation. Very small holes are drilled

with high speed CNC drilling machines, giving a wall finish with less or no

smear or epoxy, required for void free through hole plating.

PLATING

The heart of the PCB manufacturing process. The holes drilled in the

board are treated both mechanically and chemically before depositing the

copper by the electro less copper platting process.

ETCHING:

Once a multiplayer board is drilled and electro less copper deposited, the

image available in the form of a film is transferred on to the out side by photo

printing using a dry film printing process. The boards are then electrolytic

plated on to the circuit pattern with copper and tin.


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The tin-plated deposit serves an etch resist when copper in the unwanted

area is removed by the conveyors spray etching machines with chemical etch

ants. The etching machines are attached to an automatic dosing equipment,

which analyses and controls etch ants concentrations

SOLDERMASK:

Since a PCB design may call for very close spacing between conductors,

a solder mask has to be applied on the both sides of the circuitry to avoid the

bridging of conductors. The solder mask ink is applied by screening. The ink is

dried, exposed to UV, developed in a mild alkaline solution and finally cured by

both UV and thermal energy.

HOT AIR LEVELLING:

After applying the solder mask, the circuit pads are soldered using the hot

air leveling process. The bare bodies fluxed and dipped in to a molten solder

bath. While removing the board from the solder bath, hot air is blown on both

sides of the board through air knives in the machines, leaving the board

soldered and leveled. This is one of the common finishes given to the boards.

Thus the double sided plated through whole printed circuit board is

manufactured and is now ready for the components to be soldered.


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OVERALL CIRCUIT DIAGRAM:


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CHAPTERIV

FUNCTION OF RAIN DETECTION AND

WIPER MOTOR CONTROL

4.1 Introduction

This project is designed by following blocks,

1. Microcontroller2. Relays3.

DC motor

4. Gate model5. Proximity sensor

Block Diagram


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When foreside sensor gets sensed, the gate motor is turned on in one

direction and the gate is closed and stays closed until the train crosses the gate

and reaches aft side sensors. When aft side sensor gets sensed, motor turns in

opposite direction and gate opens and motor stops.

Using simple electronic components we have tried to automate the

control of railway gates. As a train approaches the railway crossing from either

side, the sensors placed at a certain distance from the gate detects the

approaching train and accordingly controls the operation of the gate. The gate

opening and closing can be done with the help of DC motor by the specific

instruction of microcontroller.

4.2 KEIL C COMPILER:

Keil development tools for the 8051 Microcontroller Architecture

support every level of software developer from the professional applications

engineer to the student just learning about embedded software development.

The industry-standard Keil C Compilers, Macro Assemblers, Debuggers,

Real-time Kernels, Single-board Computers, and Emulators support all 8051

derivatives and help you get your projects completed on schedule. The Keil

8051 Development Tools are designed to solve the complex problems facing

embedded software developers.


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When starting a new project, simply select the microcontroller you usefrom the Device Database and the Vision IDE sets all compiler,

assembler, linker, and memory options for you.

Numerous example programs are included to help you get started withthe most popular embedded 8051 devices.

The Keil Vision Debugger accurately simulates on-chip peripherals(IC, CAN, UART, SPI, Interrupts, I/O Ports, A/D Converter, D/A

Converter, and PWM Modules) of your 8051 device.

Simulation helps you understand hardware configurations and avoidstime wasted on setup problems. Additionally, with simulation, you can

write and test applications before target hardware is available.

It's been suggested that there are now as many embedded systems in

everyday use as there are people on planet Earth. Domestic appliances from

washing machines to TVs, video recorders and mobile phones, now include at

least one embedded processor. They are also vital components in a huge variety

of automotive, medical, aerospace and military systems. As a result, there is

strong demand for programmers with 'embedded' skills, and many desktop

developers are moving into this area. Embedded C is designed for programmers

with desktop experience in C, C++ or Java who want to learn the skills required

for the unique challenges of embedded systems. The book and CD-ROM

include the following key features:


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Simulator:

The Keil hardware simulator for the popular 8051 microcontroller is on

the CD-ROM so that readers can try out examples from the book - and create

new ones - without requiring additional hardware. All code is written in C, so

no assembly language is required. Industry-standard C compiler from Keil

software is included on the CD-ROM, along with copies of code examples from

the book to get you up and running very quickly.

Key techniques required in all embedded systems are covered in detail,

including the control of port pins and the reading of switches.

A complete embedded operating system is presented, with full source code on

the CD-ROM. Achieve outstanding application performance on Intel processors

using Intel C Compiler for Windows*, including support for the latest Intel

multi-core processors. For out-of-the-box productivity, Intel C Compiler plugs

into the Microsoft Visual Studio* development environment for IA-32 and

features a preview plug-in to the Microsoft Visual Studio .NET environment.

This chapter provides information about the C compiler, including

operating environments, standards conformance, organization of the compiler,

and C-related programming tools. There are a number of tools available to aid

in developing, maintaining, and improving your C programs. The two most

closely tied to C, c scope and lint, are described in this book. In addition, a man

page exists for each of these tools. Refer to the preface of this book for a list of

all the associated man pages.


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4.3 Advantages:

Avoid accidents in level crossings.No manual work is needed. It result in economy of operation. Elimination of human error. If frees human beings from mental tasks Saving in energy requirements.

4.4 Application

This project is developed in order to help the INDIANRAILWAYS in making its present working system a better

one, by eliminating some of the loopholes existing in it.

Based on the responses and reports obtained as a result ofthe significant development in the working system of

INDIAN AILWAYS, this project can be further extended to

meet the demands according to situation.


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CHAPTERV

PHOTOGRAPHY


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CHAPTERVI

CONCLUSION

The progress in science & technology is a non-stop process. New things

and new technology are being invented. As the technology grows day by day, we

can imagine about the future in which thing we may occupy every place. The

proposed system based on Atmel microcontroller is found to be more compact,

user friendly and less complex, which can readily be used in order to perform.

Several tedious and repetitive tasks. Though it is designed keeping in mind

about the need for industry, it can extended for other purposes such as

commercial & research applications. Due to the probability of high technology

(Atmel microcontroller) used this UNMANNED RAIL WAY CROSSING

system is fully software controlled with less hardware circuit. The feature makes

this system is the base for future systems. The principle of the development of

science is that nothing is impossible. So we shall look forward to a bright &

sophisticated world.


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CHAPTERVII

REFERENCES

MILL MAN J and HAWKIES C.C. INTEGRATED ELECTRONICSMCGRAW HILL, 1972

ROY CHOUDHURY D, SHAIL JAIN, LINEAR INTEGRATEDCIRCUIT, New Age International Publishers, New Delhi,2000

THE 8051 MICROCONTROLLER AND EMBEDDED SYSTEM byMohammad Ali Mazidi.

http://www.atmel.com/ http://www.microchip.com/ www.8051.com http://www.beyondlogic.org http://www.ctv.es/pckits/home.html http://www.aimglobal.org/

rail way gate

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