automatic gate control-final

7/31/2019 Automatic Gate Control-FINAL

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Automatic Railway Gate Control System

1.ABSTRACT

OBJECTIVE: The aim of this project is to Automate unmanned railway gate usingmechatronics.

PROJECT DEFINATION:

The objective of this project is to manage the control system of railway gate usingthe microcontroller. When train arrives at the sensing point alarm is triggered at the railwaycrossing point so that the people get intimation that gate is going to be closed. Then thecontrol system activates and closes the gate on either side of the track. once the traincrosses the other end control system automatically lifts the gate. For mechanical operationof the gates 1.8 step angle stepper motors are employed. Here we are using embeddedcontroller built around the 8051 family (AT89C52) for the control according to the data

pattern produced at the input port of the micro controller, the appropriate selected actionwill be taken.. The logic is produced by the program written in Embedded C language. Thesoftware program is written, by using the KEIL micro vision environment. The programwritten is then converted in HEX code after simulation and burned on to microcontroller using FLASH micro vision.

WORKING METHODOLOGY:

Present project is designed using 8051 microcontroller to avoid railway accidentshappening at unattended railway gates, if implemented in spirit. This project utilizes two

powerful IR transmitters and two receivers; one pair of transmitter and receiver is fixed atup side (from where the train comes) at a level higher than a human being in exactalignment and similarly the other pair is fixed at down side of the train direction. Sensor activation time is so adjusted by calculating the time taken at a certain speed to cross atleast one compartment of standard minimum size of the Indian railway. We haveconsidered 5 seconds for this project. Sensors are fixed at 1km on both sides of the gate.We call the sensor along the train direction as foreside sensor and the other as after sidesensor. When foreside receiver gets activated, the gate motor is turned on in one directionand the gate is closed and stays closed until the train crosses the gate and reaches aft sidesensors. When aft side receiver gets activated motor turns in opposite direction and gateopens and motor stops. Buzzer will immediately sound at the fore side receiver activation

and gate will close after 5 seconds, so giving time to drivers to clear gate area in order toavoid trapping between the gates and stop sound after the train has crossed.


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GATE CONTROL

Railways being the cheapest mode of transportation are preferred over all the other means .When we go through the daily newspapers we come across many railway accidents

occurring at unmanned railway crossings. This is mainly due to the carelessness in manualoperations or lack of workers. We, in this project has come up with a solution for the same.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 certaindistance from the gate detects the approaching train and accordingly controls the operationof the gate. Also an indicator light has been provided to alert the motorists about theapproaching train.

2.INTRODUCTION


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Introduction:The objective of this project is to manage the control system of railway gate using

the microcontroller. When train arrives at the sensing point alarm is triggered at the railwaycrossing point so that the people get intimation that gate is going to be closed. Then thecontrol system activates and closes the gate on either side of the track. once the train

crosses the other end control system automatically lifts the gate. For mechanical operationof the gates 1.8 step angle stepper motors are employed. Here we are using embeddedcontroller built around the 8051 family (AT89C52) for the control according to the data

pattern produced at the input port of the micro controller, the appropriate selected actionwill be taken.. The logic is produced by the program written in Embedded C language. Thesoftware program is written, by using the KEIL micro vision environment. The programwritten is then converted in HEX code after simulation and burned on to microcontroller using FLASH micro vision.

AT89C51 Microcontroller

The Micro controller (AT89C51) is a low power; high performance CMOS 8-bitmicro controller with 4K bytes of Flash programmable and erasable read only memory(PEROM). The on-chip Flash allows the program memory to be reprogrammed in-systemor by a conventional non-volatile memory programmer. By combining a versatile 8-bitCPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer,which provides a highly flexible and cost-effective solution to many embedded controlapplications. By using this controller the data inputs from the smart card is passed to the

parallel port of the pc and accordingly the software responds. The IDE for writing theembedded program used is KEI L software.

Keil Micro vision Integrated Development Environment .

Keil Software development tools for the 8051 micro controller family support everylevel of developer from the professional applications engineer to the student just learningabout embedded software development.The industry-standard Keil C Compilers, MacroAssemblers, Debuggers, Real-time Kernels, and Single-board Computers support ALL8051-compatible derivatives and help you get your projects completed on schedule.

The source code is written in assembly language .It is saved as ASM file with an extension.A51.the ASM file is converted into hex file using keil software. Hex file is dumped intomicro controller using LABTOOL software. At once the file is dumped and the ROM is

burnt then it becomes an embedded one.

Step Motor AdvantagesStep motors convert electrical energy into precise mechanical motion. These motors

rotate a specific incremental distance per each step. The number of steps executed controlsthe degree of rotation of the motors shaft. This characteristic makes step motors excellent


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for positioning applications. For example, a 1.8 step motor executing 100 steps will rotateexactly 180 with some small amount of non-cumulative error. The speed of step executioncontrols the rate of motor rotation. A 1.8 step motor executing steps at a speed of 200steps per second will rotate at exactly 1 revolution per second.Step motors can be very accurately controlled in terms of how far and how fast they will

rotate. The number of steps the motor executes is equal to the number of pulse commandsit is given. A step motor will rotate a distance and at a rate that is proportional to thenumber and frequency of its pulse commands.

Step motors have several advantages over other types of motors. One of the mostimpressive is their ability to position very accurately. NMBs standard step motors have anaccuracy of +/-5%. The error does not accumulate from step to step. This means that astandard step motor can take a single step and travel 1.8 +/-0.09. Then it can take onemillion steps and travel 1,800,000 +/-0.09. This characteristic gives a step motor almost

perfect repeatability. In motor terms, repeatability is the ability to return to a previouslyheld position. A step motor can achieve the same target position, revolution after

revolution.


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3.CIRCUIT DIAGRAM

4.COMPONENTS

The project consists of three main parts:

8051 microcontroller IR Transmitter IR Receiver Stepper Motor Circuit 8051 CONTROLLER

The I/O ports of the 8051 are expanded by connecting it to an 8255 chip. The 8255 is

programmed as a simple I/O port for connection with devices such as LEDs, stepper motors and sensors.

The following block diagram shows the various devices connected to the different ports of an 8255. The ports are each 8-bit and are named A, B and C. The individual portsof the 8255 can be programmed to be input or output, and can be changed dynamically.The control register is programmed in simple I/O mode with port A, port B and port C(upper) as output ports and port C (lower) as an input port.

IR CIRCUITS

This circuit has two stages: a transmitter unit and a receiver unit. The transmitter unitconsists of an infrared LED and its associated circuitry.

IR TRANSMITTER The IR LED emitting infrared light is put on in the transmitting unit. To generate IR

signal, 555 IC based astable multivibrator is used. Infrared LED is driven through transistor BC 548. IC 555 is used to construct an astable multivibrator which has two quasi-stable


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states. It generates a square wave of frequency 38kHz and amplitude 5Volts. It is requiredto switch ON the IR LED.

IR RECEIVER:The receiver unit consists of a sensor and its associated circuitry. In receiver section,

the first part is a sensor, which detects IR pulses transmitted by IR-LED. Whenever a traincrosses the sensor, the output of IR sensor momentarily transits through a low state. As aresult the monostable is triggered and a short pulse is applied to the port pin of the 8051microcontroller. On receiving a pulse from the sensor circuit, the controller activates thecircuitry required for closing and opening of the gates and for track switching. The IR receiver circuit is shown in the figure below.

STEP MOTOR ADVANTAGES

Step motors convert electrical energy into precise mechanical motion. These motorsrotate a specific incremental distance per each step. The number of steps executed controlsthe degree of rotation of the motors shaft. This characteristic makes step motors excellentfor positioning applications. For example, a 1.8 step motor executing 100 steps will rotateexactly 180 with some small amount of non-cumulative error. The speed of step executioncontrols the rate of motor rotation. A 1.8 step motor executing steps at a speed of 200steps per second will rotate at exactly 1 revolution per second.Step motors can be very accurately controlled in terms of how far and how fast they willrotate. The number of steps the motor executes is equal to the number of pulse commandsit is given. A step motor will rotate a distance and at a rate that is proportional to thenumber and frequency of its pulse commands.

Step motors have several advantages over other types of motors. One of the mostimpressive is their ability to position very accurately. NMBs standard step motors have anaccuracy of +/-5%. The error does not accumulate from step to step. This means that astandard step motor can take a single step and travel 1.8 +/-0.09. Then it can take onemillion steps and travel 1,800,000 +/-0.09. This characteristic gives a step motor almost

perfect repeatability. In motor terms, repeatability is the ability to return to a previouslyheld position. A step motor can achieve the same target position, revolution after revolution.


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5.EMBEDDED SYSTEMS

Introduction:

An Embedded system is a combination of computer hardware and software, and

perhaps additional mechanical or other parts, designed to perform a specific function.

Embedded systems are usually a part of larger, complex system. Dedicated

applications, designed to execute specific activities, are implemented and embedded insystems. These embedded applications are required to collaborate with the other

components of an enclosed system. Embedded application components interact mostly with

the non-human external environment. They continuously collect data from sensors or other

computer components and process data within real-time constraints. Embedded systems are

usually associated with dedicated hardware and specific software.

Embedding an application into system

Application and system are closely tied together

Collaborative application

Dedicated H/W and specific S/W

Interaction with non-human external environment


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Processor

Memory

Inputs Outputs


5.2 D ESIGN C ONSIDERATIONS FOR AN E MBEDDED SYSTEM

Introduction:

Unlike software designed for general-purpose computers, embedded software

cannot usually be run on other embedded system without significant modification. This is

mainly because of the incredible variety in the underlying hardware. The hardware in each

embedded system is tailored specifically to the application, in order to keep system costs

low. As a result, unnecessary circuitry is eliminated and hardware resources are shared

whenever possible.

In order to have software, there must be a place to store the executable code and

temporary storage for runtime data manipulation. These take the form of ROM and RAM,

respectively. All embedded systems also contain some type of inputs and outputs. It is

almost always the case that the outputs of the embedded system are a function of its inputs

and several other factors. The inputs to the system usually take the form of sensors and

probes, communication signals, or control knobs and buttons. The outputs are typically

displays, communication signals, or changes to the physical world.


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Example of an Embedded System

Other common design requirement include -

Processing power Memory

Development cost

Number of Units

Expected Lifetime

Reliability

Processing power

This is the amount of processing power necessary to get the hob done. A common

way to compare processing power is the MIPS (millions of instructions per second) rating.

Other important features of the processor need to be consider is register width, typically

ranges from 8 to 64 bits.

Memory:

The amount of memory (ROM and RAM) required holding the executable softwareand data it manipulates. The amount of memory required can also affect the processor

selection. In general, the register width off a processor establishes the upper limit of the

amount of memory it can access.

Development cost:


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The development cost of the hardware and software design processes is a fixed,

one-time cost, so it might be that money is no object or that this is the only accurate

measure of system cost.

Number of units:

The tradeoff between production cost and development cost is affected most by the

number of units expected to be produced and sold.

Expected lifetime:

This indicates how long must the system continue to function? This affects all sorts

of design decisions from the selection of hardware components to how much the systemmay cost to develop and produce.

Reliability:

How reliable must the final product be? If it is a childrens toy, it doesnt always

have to work right, but if it is part of a space shuttle or a car, it had sure better do what it is

supposed to each and every time.

The Basic Design REALTIME:

Designing Embedded systems is a challenging task. Most of the challenge comes

from the fact that Embedded systems have to interact with real world entities. These

interactions can get fairly complex. A typical Emebbed system might be interacting with

thousands of such entities at the same time. For example, a telephone switching system

routinely handles calls from tens of thousands of subscriber. The system has to connect

each call differently. Also, the exact sequence of events in the call might vary a lot.

Embedded systems have to respond to external interactions in a predetermined

amount of time. Successful completion of an operation depends upon the correct and timely

operation of the system. Design the hardware and the software in the system to meet the

Realtime requirements. For example, a telephone switching system must feed dial tone to

thousands of subscribers within a recommended limit of one second. To meet these

requirements, the off hook detection mechanism and the software message communication


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involved have to work within the limited time budget. The system has to meet these

requirements for all the calls being set up at any given time.

The designers have to focus very early on the Realtime response requirements.

During the architecture design phase, the hardware and software engineers work together to

select the right system architecture that will meet the requirements. This involves deciding

inter connectivity of the processors, link speeds, processor speeds, etc.

The main queries to be asked are:

Is the architecture suitable? If message communication involves too many nodes,it is likely that the system may not be able to meet the Realtime requirement due to

even mild congestion. Thus a simpler architecture has a better chance of meeting

the Realtime requirements.

Are the processing components powerful enough? A CPU with really high

utilization will lead to unpredictable Realtime behavior. Also, it is possible that thehigh priority tasks in the system will starve the low priority tasks of any CPU time.

This can cause the low priority tasks to misbehave.

Is the Operating System suitable? Assign high priority to tasks that are involved in processing Realtime critical events. Consider preemptive scheduling if Realtime

requirements are stringent. When choosing the operating system, the interrupt

latency and scheduling variance should be verified.

o Scheduling variance refers to the predictability in task scheduling times. For

example, a telephone switching system is expected to feed dialtone in less

than 500 ms. This would typically involve scheduling three to five tasks

within the stipulated time. Most operating systems would easily meet these

numbers as far as the mean dialtone delay is concerned. But general purpose


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operating systems would have much higher standard deviation in the

dialtone numbers.

o Interrupt Latency refers to the delay with which the operating system can

handle interrupts and schedule tasks to respond to the interrupt. Again,

Embedded Systems based on real-time operating systems would have much

lower interrupt latency.

6.MICROCONTROLLER

Introduction:

Microcontrollers are "embedded" inside some other device (often a consumer

product) so that they can control the features or actions of the product. Another name for a

microcontroller, therefore, is "embedded controller."

Microcontrollers are dedicated to one task and run one specific program. The program is stored in ROM (read-only memory) and generally does not change.

Microcontrollers are often low-power devices.

A microcontroller has a dedicated input device and often (but not always) has asmall LED or LCD display for output. A microcontroller also takes input from the

device it is controlling and controls the device by sending signals to different

components in the device.

For example, the microcontroller inside a TV takes input from the remote control

and displays output on the TV screen. The controller controls the channel selector,

the speaker system and certain adjustments on the picture tube electronics such as tint

and brightness. The engine controller in a car takes input from sensors such as the

oxygen and knock sensors and controls things like fuel mix and spark plug timing. A


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microwave oven controller takes input from a keypad, displays output on an LCD

display and controls a relay that turns the microwave generator on and off.

A microcontroller is often small and low cost. The components are chosen tominimize size and to be as inexpensive as possible.

A microcontroller is often, but not always, ruggedized in some way.

On the other hand, a microcontroller embedded inside a VCR hasn't beenruggedized at all.

The actual processor used to implement a microcontroller can vary widely.

Atmel 89c51 Microcontroller Description

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with

4K bytes of Flash programmable and erasable read only memory (PEROM) based on the

famous 8051 architecture. The device is manufactured using Atmels high-density

nonvolatile memory technology and is compatible with the industry-standard MCS-51

instruction set and pinout. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional nonvolatile memory programmer. Bycombining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a

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

many embedded control applications.

Features

The AT89C51 provides the following standard features:

Compatible with MCS-51 Products

Endurance: 1,000 Write/Erase Cycles

4K Bytes of In-System Reprogrammable Flash Memory

128 bytes of Internal RAM (128 x 8-bit)

32 Programmable I/O Lines


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Two 16-bit Timer/Counters

Five vector two-level interrupt architecture

A full duplex serial port

Three-level Program Memory Lock Six Interrupt Sources

B LOCK D IAGRAM :


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Figure: Block Diagram of AT89c51 Microcontroller

P IN CONFIGURATIONS :


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Figure: PDIP Type AT89c51 Pin Diagram

P IN D ESCRIPTION

VCC Supply voltage.

GND Ground.

Port 0:

Port 0 is an 8-bit open-drain bi-directional I/O port.

As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins,the pins can be used as high impedance inputs. Port 0 may also be configured to be the

multiplexed low order address/data bus during accesses to external 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. As inputs, Port

1 pins that are externally being pulled low will source current (IIL) because of the internal


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pull-ups. Port 1 also receives the low-order address bytes during Flash programming and

verification.

Port 2



pins they are pulled high by the internal pull-ups and can be used as inputs.As inputs, Port

2 pins that are externally being pulled low will source current (IIL) because of the internal

pull-ups. 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, it uses strong internal pull-ups when emitting 1s.

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 AT89C51 as listed below:

Port Pin Alternate FunctionsP3.0 RXD (serial input port)P3.1 TXD (serial output port)P3.2 INT0 (external interrupt 0)P3.3 INT1 (external interrupt 1)P3.4 T0 (timer 0 external input)P3.5 T1 (timer 1 external input)

P3.6WR (external data memory Write

strobe)

P3.7RD (external data memory read

strobe)

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


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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 output pulse for latching the low byte of the address during

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

programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and

may be used for external timing or clocking purposes. Note, however, that one ALE pulse

is skipped during each access to external Data Memory. If desired, ALE operation can be

disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a

MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-

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

PSEN

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

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 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-


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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

Oscillator Characteristics

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

which 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 in Figure 2. There are no requirements on

the duty cycle of the external clock signal, since the input to the internal clocking circuitry

is through a divide-by-two flip-flop, but minimum and maximum voltage high and low

time specifications must be observed.

Figure1: Oscillator Connections

Note: C1, C2 = 30 pF 10 pF for Crystals

= 40 pF 10 pF for Ceramic Resonators


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Figure 2: External Clock Drive Configuration

How Oscillator works

When quartz crystal is subjected to mechanical pressure, they producea measurable electrical voltage conversely when an electric current is applied to a crystal, it

will induce mechanical movement. If an ac is passed through the crystal plate the charges

oscillate back and front at the resonant frequency of crystal.

f=1/2 (((1+C/C P)/(LC)))


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Quartz crystal exhibits a property called the piezo-electric effect that is they

produce an electric voltage. When subjected to pressure along certain direction of the

crystal because of this property quartz crystal has important application in electronics

industry for controlling the frequency of radio waves.When piezo-electric crystal is used in

place of LC circuit for higher frequency stability, the oscillator is called as crystal

oscillator.

Crystal oscillator is used for stability frequency for a long period of time. The

resolution of 0.01 nm/s can be obtained. Crystal operates between f p and fs frequency (a

very narrow bandwidth).

Status of External Pins during Idle and Power-down Modes

Program Memory Lock Bits

ModeProgram

MemoryALE PSEN Port 0 Port 1 Port 2 Port3

Idle Internal 1 1 Data Data Data DataIdle External 1 1 Float Data Address Data

Power-down

Internal 0 0 Data Data Data Data

Power-

downExternal 0 0 Float Data Data Data


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On the chip are three lock bits which can be left un-programmed (U) or can be

programmed (P) to obtain the additional features listed in the table below. When lock bit 1

is programmed, the logic level at the EA pin is sampled and latched during reset. If the

device is powered up without a reset, the latch initializes to a random value, and holds that

value until reset is activated. It is necessary that the latched value of EA be in agreement

with the current logic level at that pin in order for the device to function properly.

Lock Bit Protection Modes

Program Lock Bits

Protection TypeLB1 LB2 LB3

1 U U U No program lock features

2 P U U

MOVC instructions executed from external program

memory are disabled from fetching code bytes from

internal memory, EA is sampled and latched on

reset, and further programming of the Flash is

disabled3 P P U Same as mode 2, also verify is disabled4 P P P Same as mode 3, also external execution is disabled

Programming the Flash

The AT89C51 is normally shipped with the on-chip Flash memory array in theerased state (that is, contents = FFH) and ready to be programmed. The programming

interface accepts either a high-voltage (12-volt) or a low-voltage (VCC) program enable

signal.


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The low-voltage programming mode provides a convenient way to program the

AT89C51 inside the users system, while the high-voltage programming mode is

compatible with conventional third-party Flash or EPROM programmers.

Reading the Signature Bytes:

The signature bytes are read by the same procedure as a normal verification of

locations 030H, 031H, and 032H, except that P3.6 and P3.7 must be pulled to a logic low.

The values returned are as follows.

(030H) = 1EH indicates manufactured by Atmel

(031H) = 51H indicates 89C51

(032H) = FFH indicates 12V programming

(032H) = 05H indicates 5V programming.

Programming Interface

Every code byte in the Flash array can be written and the entire array can be erased

by using the appropriate combination of control signals. The write operation cycle is self

timed and once initiated, will automatically time itself to completion. All major

programming vendors offer worldwide support for the Atmel microcontroller series. Please

contact your local programming vendor for the appropriate software revision.

Flash Programming Modes

Mode RST PSEN ALE/PROGEA /

VPPP2.6 P2.7 P3.6 P3.7

Write Code Data H L H/12V L H H H

Read Code Data H L H H L L H H

Write

Lock

Bit-1 H L H/12V H H H H

Bit-2 H L H/12V H H L L

Bit-3 H L H/12V H L H L

Chip Erase H L H/12V H L L LRead Signature

ByteH L H H L L L L

Note: Chip Erase requires a 10 ms PROG pulse.

E XTERNAL P ROGRAM M EMORY R EAD C YCLE


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External Data Memory Read Cycle

External Data Memory Write Cycle


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External Clock Drive Waveforms

External Clock Drive

Symbol Parameter Min Max Units1/tCLCL Oscillator Frequency 0 24 MHztCLCL Clock Period 41.6 ns

techs High Time 15 nstalc Low Time 15 nstalc Rise Time 20 nstechs Fall Time 20 ns


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7.HARDWARE DISCRIPTION

7.1 STEPER MOTOR

Introduction:

Stepper motors convert electrical energy into precise mechanical motion. These

motors rotate a specific incremental distance per each step. The number of steps executed

controls the degree of rotation of the motors shaft. This characteristic makes step motors

excellent for positioning applications. For example, a 1.8 step motor executing 100 steps

will rotate exactly 180 with some small amount of non-cumulative error. The speed of

step execution controls the rate of motor rotation. A 1.8 step motor executing steps at a

speed of 200 steps per second will rotate at exactly 1 revolution per second.

Stepper motors can be very accurately controlled in terms of how far and how fast

they will rotate. The number of steps the motor executes is equal to the number of pulse

commands it is given. A step motor will rotate a distance and at a rate that is proportional

to the number and frequency of its pulse commands.

Basic Stepper Motor System

The diagram above shows a typical step motor based system. All of these parts

must be present in one form or another. Each components performance will have an effect

on the others. By altering the frequency of the pulse train, the pulse generator can instruct


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the motor to accelerate, run at a speed, decelerate or stop. A pulse generator must be

present otherwise the motor will not move. Next is the motor driver.

The driver takes the pulses from the pulse generator and determines how and when

the windings should be energized. The windings must be energized in a specific sequence

to generate motion. Finally there is the step motor itself. A step motor has two primary

parts; the rotor, the moving piece, and the stator, the stationary piece. The stator contains

coils of wire called windings. The rotor spins on bearings or bushings inside the stator. All

step motors operate through the principle of the rotor following a rotating magnetic field

created by sequencing the flow of current through the stator windings. Each NMB stepmotor has two phases, which are groups of electrically connected windings. As current is

passed through each phase, the motor takes steps or small movements to keep in

synchronism with the magnetic field. The degree of rotation per step depends on the style

of driver used and the construction of the motor.

Step Motor Advantages:

Accuracy & Repeatability Ability to position accurately.

Responsiveness & Quick Acceleration Step motors have low rotor inertia,

allowing them to get up to speed quickly. This makes step motors an excellent choice for

short, quick moves.

Excellent torque for their size Step motors have the highest torque per cubic

inch of any motor.

Positioning Stability Unlike other types of motors, step motors can be held

completely motionless in their stopped position.

Construction and Operating the Hybrid STEP MOTOR

Figure 1a depicts a 1.8 hybrid step motor. The rotor contains a permanent magnet

similar to those found in permanent magnet step motors. Hybrid rotors are axially


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magnetized, one end polarized north and the other polarized south. Both the rotor and the

stator assemblies of hybrid motors have tooth-like projections. To understand the rotors

interaction with the stator, examine the construction of a 1.8 (the most common

resolution) hybrid step motor.

The two cups are oriented so that the teeth of the top cup are offset to the teeth of

the bottom cup by 3.6. Second, the stator has a two-phase construction. The winding coils,

90 apart from one another, make up each phase. Each phase is wound so that the poles

180 apart are the same polarity, while the poles 90 apart are the opposite polarity. When

the current in a phase is reversed, is the polarity, meaning that any winding coil can be

either a north pole or a south pole. As shown in fig. 1b below, when phase A is energized,

the windings at 12 oclock and 6 oclock are north poles and the windings at 3 oclock and

9 oclock are south poles.The windings at 12 and 6 would attract the teeth of the magnetically south end of

the rotor, and windings at 3 and 9 would attract the teeth of the magnetically north end of

the rotor.

.


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7.2 CAPACITORS

Introduction:

An electrolytic capacitor is a type of capacitor typically with a larger capacitance per unit volume than other types, making them valuable in relatively high-current and low-frequency electrical circuits. This is especially the case in power-supply filters, where theystore charge needed to moderate output voltage and current fluctuations, in rectifier output,and especially in the absence of rechargeable batteries that can provide similar low-frequency current capacity. They are also widely used as coupling capacitors in circuitswhere AC should be conducted but DC should not; the large value of the capacitanceallows them to pass very low frequencies.

The electrolytic capacitor was invented in 1886 by Charles Pollack. It was largelyresponsible for the development of mains-powered radio receivers, since it permitted thefiltering of the 50-60 hertz power supplied to residences, after it was rectified to power theradio tubes. This was not practical without the small volume and low cost of electrolyticcapacitors.

Construction

Aluminum electrolytic capacitors are constructed from two conducting aluminumfoils, one of which is coated with an insulating oxide layer, and a paper spacer soaked inelectrolyte. The foil insulated by the oxide layer is the anode while the liquid electrolyteand the second foil act as cathode. This stack is then rolled up, fitted with pin connectorsand placed in a cylindrical aluminum casing. The two most popular geometries are axialleads coming from the center of each circular face of the cylinder, or two radial leads or lugs on one of the circular faces. Both of these are shown in the picture

Polarity

In aluminum electrolytic capacitors, the layer of insulating aluminum oxide on thesurface of the aluminum plate acts as the dielectric, and it is the thinness of this layer thatallows for a relatively high capacitance in a small volume. The aluminum oxide layer canwithstand an electric field strength of the order of 10 9 volts per meter. The combination of high capacitance and high voltage result in high energy density.

Unlike most capacitors, electrolytic capacitors have a voltage polarity requirement.The correct polarity is indicated on the packaging by a stripe with minus signs and possiblyarrowheads, denoting the adjacent terminal that should be more negative than the other.This is necessary because a reverse-bias voltage will destroy the center layer of dielectric


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material via electrochemical reduction (see redo reactions). Without the dielectric materialthe capacitor will short circuit, and if the short circuit current is excessive, then theelectrolyte will heat up and either leak or cause the capacitor to explode.

Modern capacitors have a safety valve, typically either a scored section of the can,

or a specially designed end seal to vent the hot gas/liquid, but ruptures can still be dramatic.Electrolytic can withstand a reverse bias for a short period of time, but they will conductsignificant current and not act as a very good capacitor. Most will survive with no reverseDC bias or with only AC voltage, but circuits should be designed so that there is not aconstant reverse bias for any significant amount of time. A constant forward bias is

preferable, and will increase the life of the capacitor.

These are the different schematic symbols for electrolytic capacitors. The minus or Nmarked side of the physical capacitor is equivalent to the node opposite to the plus sign onits symbolic equivalent. Tip: Take notice of the shape of the symbols and the placement of the positive and negative nodes, because most schematics do not print the "+", but rely onthe symbol itself instead.

note: caps in metal can have the color mark at the minus side !

Polarity of caps with wires:

axial: the minus wire is connected to the case, the plus wire is isolated. radial = single ended: a vertical color stripe indicates the minus side.

For the polarity of SMD caps see pica:
http://en.wikipedia.org/wiki/Image:Cap-elko-smd-polarity.jpg


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Electrolyte

The electrolyte is usually boric acid or sodium borate in aqueous solution together with various sugars or ethylene glycol which are added to retard evaporation. Care should

be taken to avoid ingestion of or eye contact with the electrolyte, and any areas of the body

where skin contact has occurred should be washed in good time. It is important to followsafe working practice and to use appropriate protective equipment, notably gloves andsafety glasses, when working with the electrolyte. Some very old tantalum electrolytic,often called "Wet-slug", contain the more hazardous sulfuric acid, however most of theseare no longer in service due to corrosion.

Capacitance

The capacitance value of any capacitor is a measure of the amount of electriccharge stored per unit of potential difference between the plates. The basic unit of capacitance is a farad, however this unit has been too large for general use until the

invention of the Double-layer capacitor, so microfarad, nanofarad and microfarad are morecommonly used. These are usually abbreviated to if or of, no and puff

Many conditions determine a capacitor's value, such as the thickness of thedielectric and the plate area. In the manufacturing process, electrolytic capacitors are madeto conform to a set of preferred numbers. By multiplying these base numbers by a power of ten, any practical capacitor value can be achieved, which is suitable for most applications.

A standardized set of capacitor base numbers was devised so that the value of anymodern electrolytic capacitor could be derived from multiplying one of the modernconventional base numbers 1.0 , 1.5 , 2.2 , 3.3 , 4.7 or 6.8 by a power of ten. Therefore, it is

common to find capacitors with values of 10, 15, 22, 33, 47, 68, 100, 220, and so on. Usingthis method, values ranging from 0.1 to 4700 are common in most applications. Values aregenerally in microfarads (F).

Most electrolytic capacitors have a tolerance range of 20 %, meaning that themanufacturer is stating that the actual value of the capacitor lies within 20 % of its labeledvalue. Selection of the preferred series ensures that any capacitor can be sold as a standardvalue, within the tolerance.


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Super capacitor

MC and BC series super capacitors (up to 3000 farad capacitance) produced by MaxwellTechnologies

Super capacitors , also known as ultra capacitors or electrochemical double layercapacitors (EDLC), are electrochemical capacitors that have an unusually high energydensity when compared to common capacitors, typically on the order of thousands of timesgreater than a high-capacity electrolytic capacitor. For instance, a typical D-cell sizedelectrolytic capacitor will have a storage capacity measured in microfarads, while the samesize super capacitor would store several farads, an improvement of about 10,000 times.Larger commercial super capacitors have capacities as high as 5,000 farads.

Super capacitors have a variety of commercial applications, notably in "energy smoothing"and momentary-load devices. Some of the earliest uses were motor startup capacitors for large engines in tanks and submarines, and as the cost has fallen they have started to appear on diesel trucks and railroad locomotives. More recently they have become a topic of someinterest in the green energy world, where their ability to quickly soak up energy makesthem particularly suitable for regenerative braking applications, whereas batteries havedifficulty in this application due to slow charging times. If the LEES or Ester devices can

be commercialized, they will make an excellent replacement for batteries in all-electric carsand plug-in hybrids, as they combine quick charging, temperature stability and excellentsafety properties.


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Concept

Comparison of construction diagrams of three capacitors. Left: "normal" capacitor, middle:electrolytic, right: super capacitor

In a conventional capacitor, energy is stored by the removal of charge carriers, typicallyelectrons, from one metal plate and depositing them on another. This charge separationcreates a potential between the two plates, which can be harnessed in an external circuit.The total energy stored in this fashion is a combination of the number of charges stored andthe potential between the plates.

In contrast with traditional capacitors, super capacitors do not have a conventionaldielectric, as such. They are based on a structure that contains an electrical double layer. Ina double layer, the effective thickness of the "dielectric" is exceedingly thinon the order of nanometersand that, combined with the very large surface area, is responsible for their extraordinarily high capacitances in practical sizes.

In an electrical double layer, each layer by itself is quite conductive, but the physicsat the interface where the layers are effectively in contact means that no significant currentcan flow between the layers. However, the double layer can withstand only a low voltage,which means that super capacitors rated for higher voltages must be made of matchedseries-connected individual super capacitors, much like series-connected cells in higher-voltage batteries.


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History:

The super capacitor effect was first noticed in 1957 by General Electric engineersexperimenting with devices using porous carbon electrode. It was believed that the energywas stored in the carbon pores and it exhibited "exceptionally high capacitance", although

the mechanism was unknown at that time.

General Electric did not immediately follow up on this work, and it was StandardOil of Ohio that eventually developed the modern version of the devices in 1966 after accidentally re-discovering the effect while working on experimental fuel cell designs.Their cell design used two layers of activated charcoal separated by a thin porous insulator.Standard Oil also failed to commercialize their invention, licensing the technology to NEC,who finally marketed the results as super capacitors in 1978, to provide backup power for maintaining computer memory. In 2005, the ultra capacitor market was between US$272 million and $400 million, depending on the source. It is rapidly growing, especially inthe automotive sector.

Recently, all solid state micrometer-scale super capacitors based on advancedsupersonic conductors had been recognized as critical electron component of future sub-voltage and deep-sub-voltage nanoelectronics and related technologies (22 nmtechnological node of CMOS and beyond).

Technology advantages

Due to the capacitor's high number of charge-discharge cycles (millions or morecompared to 2001000 for most commercially available rechargeable batteries) there wereno disposable parts during the whole operating life of the device, which makes the device

environmentally friendly. storing energy from other sources for load balancing purposesand then using any excess energy to charge the batteries only at opportune times.

Other advantages of super capacitors compared with rechargeable batteries areextremely low internal resistance or ESR, high efficiency (up to 97-98%), high output

power, extremely low heating levels, and improved safety. According to ITS (Institute of Transportation Studies, Davis, CA) test results, the specific power of super capacitors canexceed 6 kW/kg at 95% efficiency

The idea of replacing batteries with capacitors in conjunction with novel alternativeenergy sources became a conceptual umbrella of the Green Electricity (GEL) Initiative,

introduced by Dr. Alexander Bell.


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Transportation applications

China is experimenting with a new form of electric bus (casabas) that runs without power lines using power stored in large onboard super capacitors, which are quicklyrecharged whenever the electric bus stops at any bus stop (under so-called electric

umbrellas ), and fully charged in the terminus. A few prototypes were being tested inShanghai in early 2005. In 2006, two commercial bus routes began to use super capacitor buses; one of them is route 11 in Shanghai.

In 2001 and 2002, VAG, the public transport operator in Nuremberg, Germanytested a bus which used a diesel-electric drive system with super capacitors.

Other companies from the public transport manufacturing sector are developingsuper capacitor technology: The Transportation Systems division of Siemens AG isdeveloping a mobile energy storage based on double-layer capacitors called Subic EnergyStorage and also Sitars SES, a stationary version integrated into the trackside power

supply. The company Cudgeled is also developing a super capacitor-based energy storagesystem.

Resistors, capacitors and inductors

Resistor values are always coded in ohms , capacitors in microfarads (pF), inductors in micro henries (H), and transformers in volts .

band A is first significant figure of component value band B is the second significant figure band C is the decimal multiplier band D if present, indicates tolerance of value in percent (no color means 20%)

For example, a resistor with bands of yellow, violet, red, and gold will have firstdigit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros:4,700 ohms. Gold signifies that the tolerance is 5%, so the real resistance could lieanywhere between 4,465 and 4,935 ohms.

Resistors manufactured for military use may also include a fifth band whichindicates component failure rate ( reliability ); refer to MIL-HDBK -199 for further details.

The Standard EIA Color Code Table per EIA-RS-279 is as follows:
http://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Henry_(inductance)http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Volthttp://www.okaphone.nl/calc/resistor.shtml?ohm=4700&tol=5http://en.wikipedia.org/wiki/Reliabilityhttp://en.wikipedia.org/wiki/MIL-HDBKhttp://en.wikipedia.org/wiki/Electronic_Industries_Alliancehttp://en.wikipedia.org/wiki/Image:Resistor_bands.pnghttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Henry_(inductance)http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Volthttp://www.okaphone.nl/calc/resistor.shtml?ohm=4700&tol=5http://en.wikipedia.org/wiki/Reliabilityhttp://en.wikipedia.org/wiki/MIL-HDBKhttp://en.wikipedia.org/wiki/Electronic_Industries_Alliance


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Color 1 st band 2 nd band 3 rd band (multiplier) 4 th band (tolerance) Temp. Coefficient

Black 0 0 10 0

Brown 1 1 10 1 1% (F) 100 pap

Red 2 2 10 2 2% (G) 50 pap

Orange 3 3 10 3 15 pap

Yellow 4 4 10 4 25 pap

Green 5 5 10 5 0.5% (D)

Blue 6 6 10 6 0.25% (C)

Violet 7 7 10 7 0.1% (B)

Grey 8 8 10 8 0.05% (A)

White 9 9 10 9

Gold 0.1 5% (J)

Silver 0.01 10% (K)

None 20% (M)

Note : red to violet are the colors of the rainbow where red is low energy and violet ishigher energy.
http://en.wikipedia.org/wiki/Blackhttp://en.wikipedia.org/wiki/Brownhttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Orange_(color)http://en.wikipedia.org/wiki/Yellowhttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Violet_(color)http://en.wikipedia.org/wiki/Grey_(color)http://en.wikipedia.org/wiki/Whitehttp://en.wikipedia.org/wiki/Gold_(color)http://en.wikipedia.org/wiki/Silver_(color)http://en.wikipedia.org/wiki/Blackhttp://en.wikipedia.org/wiki/Brownhttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Orange_(color)http://en.wikipedia.org/wiki/Yellowhttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Violet_(color)http://en.wikipedia.org/wiki/Grey_(color)http://en.wikipedia.org/wiki/Whitehttp://en.wikipedia.org/wiki/Gold_(color)http://en.wikipedia.org/wiki/Silver_(color)


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7.3 POWER SUPPLY:

CIRCUIT DIAGRAM:

POWER SUPPLY:

To run the electronic gadget at home it is provided by some power supply. The

microcontroller used (at89c51) requires 12v D.C supply. The DTMF receiver used

(mt8870) requires 5v D.C. so design of these regulated power supply is also an important

part in hardware design. The A.C power supply from mains is taken and regulated using

the rectifiers.

For design of a regulated power supply components used are:

Transformer.

Diodes.

Rectifiers.

Regulated IC chips.

Capacitive filters.

Trans former:

A transformer is required to couple the mains to the actual power supply circuit.

This is required to isolate the mains from the actual regulated power supply circuit and the

other part of the kit. This isolation eliminates the dame of the kit to any power supply

variations or from a faulty shock.

IN4007

0

1

2

7805

LED

1

21000uf

TRANSFORMER

6

8

1

IN40075

1k

2

1100uf

230 VAC

SUPPLY

50 HZ 4


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For a transformer shown below:

:

Diodes:

In bride rectifier four diodes are used. The specifications of diodes are chosen

as:

PIV > input voltage.

Si diode is better.

Power dissipation is kept fixed with respect to current through the diode.

Junction capacitance need not be considered for frequencies


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Current Flow in the Bridge Rectifier

For both positive and

negative swings of the

transformer, there is a

forward path through the diode bridge. Both conduction paths cause current to flow

in the same direction through the load resistor, accomplishing full-wave

rectification.

While one set of diodes is forward biased, the other set is reverse biased and

effectively eliminated from the circuit.

Diode Bridge :

A diode bridge is an arrangement of four diodes connected in a bridge circuit asshownbelow, that provides the same polarity of output voltage for any polarity of the input

voltage. When used in its most common application, for conversion of alternating current

(AC) input into direct current (DC) output, it is known as a bridge rectifier. The diagram

describes a diode-bridge design known as a full-wave rectifier or Graetz circuit. This

design can be used to rectify single phase AC when no transformer center tap is available

Bridge Rectifier Circuit :
http://en.wikipedia.org/wiki/Image:Diodebridge1.png


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The essential feature of this arrangement is that for both polarities of the voltage at

the bridge input, the polarity of the output is constant.

Capacitors :

Capacitive filters are used stabilized or perfect regulation of the voltage. The

capacitive filters are opted because, they are more efficient. But they are also more costly.

Different types of capacitors are:

1. Ceramic capacitors.

2. Electrolyte capacitors.3. Paper/Mica capacitors.

4. Silver capacitors.

5. Tantalum capacitors.

Ceramic, Paper/Mica, Silver are nonpolarized capacitors. Electrolyte and Tantalum are

polarized capacitors. For high frequency, Ceramic capacitors are used. For low frequencies,

Electrolyte capacitors are used.

Linear regulated ICs:

Linear regulated ICs are used for best regulated output. The output from these

regulated ICs is given to microcontroller and DTMF receiver. These linear regulated ICs

are self protective (any accidental shot circuit in the IC is grounded automatically).

78xx series ICs are used for +ve supply.

79xx series ICs are used for -ve supply.

78xx and 79xx series ICs are fixed voltage regulators. LM 317 is a variable voltage

regulator.


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ULN2803buffer:

Features: 500-mA Rated Collector Current (Single

Output)

High-Voltage Outputs . . . 50 V

Output Clamp Diodes

Inputs Compatible With Various Types of logic

Relay Driver Applications

Compatible with ULN2800A Series

description/ordering information:The ULN2803A is a high-voltage, high-

current Darlington transistor array. The device

consists of eight nun Darlington pairs that feature high-voltage outputs with common-

cathode clamp diodes for switching inductive loads. The collector-current rating of each

Darlington pair is 500 mA. The Darlington pairs may be connected in parallel for higher

current capability.

Applications include relay drivers, hammer drivers, lamp drivers, display drivers

(LED and gas discharge), line drivers, and logic buffers. The ULN2803A has a 2.7-k series

base resistor for each Darlington pair for operation directly with TTL or 5-V CMOSdevices.


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Logic diagram:

LOGIC DIAGRAM FOR THE ULN2803buffer


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A useful mnemonic for remembering the first ten color codes matches the first letter of the color code, by order of increasing magnitude . There are many variations:

Bad Beer R ots Our Young G uts But Vodka Goes W ell Bright Boys R ave Over Young G irls But Veto Getting W ed B. B. R O Y of G reat Britain has a Very G ood W ife Big Boys R ace Our Young G irls But Violet G enerally W ins Better Be R ight O r Your G reat Big Venture Goes W est Black Beauty R an O ver Yellow G rass By Violent G rey W aters Bad Boys R ace Over Yonder G reen But Victory Goes W anting Black Birds R oam Over Your Garden But Vultures Go W est Bye Bye R osie O ff You Go Birmingham Via G reat W eston

The word "Bad" in the first mnemonic and "Bright" in the second mnemonic are oftenreplaced with the word "Black" since black comes before brown in the color code. While

the second mnemonic is certainly the most offensive of these, all except the third lack asobriety that might be desirable, especially in a teaching context. A more staid memoryaide uses the fact that the central part of the code follows the color spectrum , without the ifor indigo. That is,

Black Brown Roy G. Big G ray W hite

The most common variation of the mnemonic for the EIA color code generally doesn'tstay posted on this page for long due to its choice of words which is more offensive tomany today than when it was originated (mid 1920's). Refer to the discussion for details.

Besides the ten colors of the main value code, the tolerance code is oftenremembered as "for Gold or Silver" appended to the more offensive mnemonic, or " GetSome Now" where Now refers to none for 20%.

If it is difficult to recall that black comes before brown in the color code, it may behelpful to use the position of white at the end of the color code as a key to remember that

black (and not brown) is at the beginning.
http://en.wikipedia.org/wiki/Mnemonichttp://en.wikipedia.org/wiki/Magnitude_(mathematics)http://en.wikipedia.org/wiki/Color_spectrumhttp://en.wikipedia.org/wiki/Roy_G._Bivhttp://en.wikipedia.org/wiki/Roy_G._Bivhttp://en.wikipedia.org/wiki/Roy_G._Bivhttp://en.wikipedia.org/wiki/Talk:Electronic_color_codehttp://en.wikipedia.org/wiki/Mnemonichttp://en.wikipedia.org/wiki/Magnitude_(mathematics)http://en.wikipedia.org/wiki/Color_spectrumhttp://en.wikipedia.org/wiki/Roy_G._Bivhttp://en.wikipedia.org/wiki/Talk:Electronic_color_code


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Other languages have other mnemonics for this color code. A rough translation of the French is "Don't eat anything or I'll beat you violently, big animal."

Examples

From top to bottom:

Green-Blue-Black-Black-Browno 560 1%

Red-Red-Orange-Goldo 22,000 5%

Yellow-Violet-Brown-Goldo 470 5%

Blue-Gray-Black-Goldo 68 5%

Note: The sizes of the resistors depend only on the power they can dissipate, and do notaffect their value.

What do resistors do?

Resistors limit current. In a typical application, a resistor is connected in series withan LED:
http://en.wikipedia.org/wiki/Image:Resistors_color_code.jpg


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Enough current flows to make the LED light up, but not so much that the LED is

damaged. Later in this Chapter, you will find out how to calculate a suitable value for thisresistor. (LEDs are described in detail in Chapter 5.)

The 'box' symbol for a fixed resistor is popular in the UK and Europe. A 'zig-zag'symbol is used in America and Japan:

Resistors are used with transducers to make sensor subsystems . Transducers areelectronic components which convert energy from one form into another, where one of theforms of energy is electrical. A light dependent resistor , or LDR , is an example of aninput transducer . Changes in the brightness of the light shining onto the surface of theLDR result in changes in its resistance. As will be explained later, an input transducer ismost often connected along with a resistor to to make a circuit called a potential divider .In this case, the output of the potential divider will be a voltage signal which reflectschanges in illumination.

Microphones and switches are input transducers. Output transducers includeloudspeakers, filament lamps and LEDs. Can you think of other examples of transducers of each type?


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7.4 C OLOR CODING

How can the value of a resistor be worked out from the colours of the bands? Eachcolor represents a number according to the following scheme:

Number Color

0 black

1 brown

2 red

3 orange

4 yellow

5 green

6 blue

7 violet

8 grey

9 white

The first band on a resistor is interpreted as the FIRST DIGIT of the resistor value.For the resistor shown below, the first band is yellow, so the first digit is 4:


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The second band gives the SECOND DIGIT. This is a violet band, making thesecond digit 7. The third band is called the MULTIPLIER and is not interpreted in quite thesame way. The multiplier tells you how many nougats you should write after the digits youalready have. A red band tells you to add 2 nougats. The value of this resistor is therefore4 7 0 0 ohms, that is, 4 700 , or 4.7 . Work through this example again to confirm

that you understand how to apply the color code given by the first three bands.

The remaining band is called the TOLERANCE band. This indicates the percentageaccuracy of the resistor value. Most carbon film resistors have a gold-colored tolerance

band, indicating that the actual resistance value is with + or - 5% of the nominal value.Other tolerance colours are:

Tolerance Color

1% brown

2% red5% gold

10% silver

When you want to read off a resistor value, look for the tolerance band, usuallygold, and hold the resistor with the tolerance band at its right hand end. Reading resistor values quickly and accurately isn't difficult, but it does take practice!


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8.SOFTWARE DISCRIPTION8.1 KEIL MICROVISION

-An IDE for Microcontrollers

Introduction:

Keil development tools for the 8051 Microcontroller Architecture support everylevel of software developer from the professional applications engineer to the student justlearning about embedded software development.

The industry-standard Keil C Compilers, Macro Assemblers, Debuggers, Real-timeKernels, Single-board Computers, and Emulators support all 8051 derivatives and help youget your projects completed on schedule

The Keil 8051 Development Tools are designed to solve the complex problems facingembedded software developers.

When starting a new project, simply select the microcontroller you use from theDevice Database and the Vision IDE sets all compiler, assembler, linker, andmemory options for you.

Numerous example programs are included to help you get started with the 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 PWMModules) of your 8051 device. Simulation helps you understand hardwareconfigurations and avoids time wasted on setup problems. Additionally, withsimulation, you can write and test applications before target hardware is available.

When you are ready to begin testing your software application with targethardware, use the MON51, MON390, MONADI, or FlashMON51 Target Monitors,the ISD51 In-System Debugger, or the ULINK USB-JTAG Adapter to downloadand test program code on your target system.

The Vision3 IDE is a Windows-based software development platform that combines arobust editor, project manager, and make facility. Vision3 integrates all tools includingthe C compiler, macro assembler, linker/locator, and HEX file generator.

Vision3 helps expedite the development process of your embedded applications by providing the following:


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Full-featured source code editor, Device database for configuring the development tool setting, Project manager for creating and maintaining your projects, Integrated make facility for assembling, compiling, and linking your embedded

applications,

Dialogs for all development tool settings, True integrated source-level Debugger with high-speed CPU and peripheralsimulator,

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 FlashROM,

Links to development tools manuals, device datasheets & users guides.

The Vision3 IDE offers numerous features and advantages that help you quickly andsuccessfully develop embedded applications. They are easy to use and are guaranteed to

help you achieve your design goals.The Vision3 IDE and Debugger is the central part of the Keil development tool chain.Vision3 offers a Build Mode and a Debug Mode .

In the Vision3 Build Mode you maintain the project files and generate the application.

In the Vision3 Debug Mode you verify your program either with a powerful CPU and peripheral simulator or with the Keil ULINK USB-JTAG Adapter (or other AGDIdrivers) that connect the debugger to the target system. The ULINK allows you also todownload your application into Flash ROM of your target system .

ABOUT THE ENVIRONMENT
http://www.keil.com/support/man/docs/uv3/uv3_creating_apps.htmhttp://www.keil.com/support/man/docs/uv3/uv3_creating_apps.htmhttp://www.keil.com/support/man/docs/uv3/uv3_debugging.htmhttp://www.keil.com/support/man/docs/uv3/uv3_creating_apps.htmhttp://www.keil.com/support/man/docs/uv3/uv3_debugging.htmhttp://www.keil.com/ulink/http://www.keil.com/support/man/docs/uv3/uv3_creating_apps.htmhttp://www.keil.com/support/man/docs/uv3/uv3_debugging.htmhttp://www.keil.com/support/man/docs/uv3/uv3_creating_apps.htmhttp://www.keil.com/support/man/docs/uv3/uv3_debugging.htmhttp://www.keil.com/ulink/


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The Vision3 screen provides you with a menu bar for command entry , a tool barwhere you can rapidly select command buttons, and windows for source files, dialogboxes, and information displays. Vision3 lets you simultaneously open and viewmultiple source files.Vision3 has two operating modes :

Build Mode : Allows you to translate all the application files and to generateexecutable programs. The features of the Build Mode are described under CreatingApplications.

Debug Mode : Provides you with a powerful debugger for testing your application.The Debug Mode is described in Testing Programs.

In both operating modes you may use the source editor of Vision3 to modify your source code. The Debug mode adds additional windows and stores an own screen layout.The following picture shows a typical configuration of Vision3 in the Debug Mode.

The tabs of the Project Workspace give you access to:o Files and Groups of the project.o CPU Registers during debugging.o Tool and project specific on-line Books . o Text Templates for often used text blocks.o 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 fileaccess. The Memory Window gives access to the memory areas in display various

formats. The Watch & Call Stack Window allows you to review and modify program

variables and displays the current function call tree. The Workspace is used for the file editing, disassembly output, and other debug

information. The Peripheral Dialogs help you to review the status of the on-chip peripherals in

the microcontroller.

8.2 S OFTWARE D EVELOPMENT C YCLE
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Home Vision3 Overview Software Development Cycle

When you use the Keil Vision3, the project development cycle is roughly the same asit is for any other software development project.

1. Create a project, select the target chip from the device database, and configure thetool settings.2. Create source files in C or assembly.3. Build your application with the project manager.4. Correct errors in source files.5. Test the linked application.

The following block diagram illustrates the complete Vision3 software developmentcycle. Each component is described below .

Vision3 IDE

The Vision3 IDE combines project management, a rich-featured editor withinteractive error correction, option setup, make facility, and on-line help. Use Vision3 tocreate your source files and organize them into a project that defines your targetapplication. Vision3 automatically compiles, assembles, and links your embeddedapplication and provides a single focal point for your development efforts .

C Compiler & Macro Assembler

Source files are created by the Vision3 IDE and are passed to the C or EC++Compiler or Macro Assembler. The compiler and assembler process source files and createreloadable object files .

Library Manager

The library manager allows you to create object library from the object files created by the compiler and assembler. Libraries are specially formatted, ordered programcollections of object modules that may be used by the linker at a later time. When the linker

processes a library, only those object modules in the library that are necessary to create the program are used.

Linker/Locator

The Linker/Locator creates an executable program file using the object modulesextracted from libraries and those created by the compiler and assembler. An executable

program file (also called absolute object module) contains no reloadable code or data. Allcode and data reside at fixed memory locations.
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This executable program file may be used:

To program an Flash ROM or other memory devices, With the Vision3 Debugger for simulation and target debugging, With an in-circuit emulator for the program testing .

Vision3 Debugger

The Vision3 symbolic, source-level debugger is ideally suited for fast, reliable program debugging. The debugger includes a high-speed simulator that let you simulate anmicrocontroller system including on-chip peripherals and external hardware. The Vision3Debugger provides several ways for you to test your programs on real target hardware.

Use the Keil ULINK USB-JTAG adapter for Flash downloading and software testof your program via on-chip debugging system like the Embedded ICE macro cellthat is integrated in many ARM devices.

Use the AGDI interface to attach use the Vision3 Debugger front end with your target system using other debuggers like Monitor, In-System Debugger, or Emulator.

At Keil Software, we are dedicated to provide you with the best embeddeddevelopment tools and documentation available. If you have suggestions or commentsregarding any of the on-line manuals accompanying this product, please contact us. If youthink you have discovered a problem with the software, do the following before callingtechnical support.

1. Read the sections in this manual that pertains to the job or task you are trying to

accomplish.2. Make sure you are using the most current version of the software and utilities.Check www.keil.com/update to make sure that you have the latest softwareversion.

3. Isolate the problem to determine if it is a problem with the assembler, compiler,linker, debugger, or another development tool.

4. Further isolate software problems by reducing your code to a few lines.

If you are still experiencing problems after following these steps, report them to

our technical support group. Please include your product serial number and versionnumber. We prefer that you send the problem via email. If you contact us by fax, be sure toinclude your name and telephone numbers (voice and fax) where we can reach you.

Try to be as detailed as possible when describing the problem you are having. Themore descriptive your example, the faster we can find a solution. If you have a single-pagecode example demonstrating the problem, please email it to us. If possible, make sure that
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your problem can be duplicated with the Vision3 Simulator. Please try to avoid sendingcomplete applications or long listings as this slows down our response to you.

The Vision3 User Interface consists of menus, toolbar buttons, keyboard shortcuts,dialog boxes, and windows that you use as you interact with and manage the various

aspects of your embedded project. The menu bar provides menus for editor operations, project maintenance,

development tool option settings, program debugging, external tool control,window selection and manipulation, and on-line help.

The toolbar buttons allow you to rapidly execute Vision3 commands. A StatusBar provides editor and debugger information. The various toolbars and the status

bar can be enabled or disabled from the View Menu commands. Keyboard shortcuts offer quick access to Vision3 commands and may be

configured via the menu command Edit Configuration - Shortcut Key .

The following sections list the Vision3 commands that can be reached by menucommands , toolbar buttons , and keyboard shortcuts . The Vision3 commands aregrouped mainly based on the appearance in the menu bar:

File Menu and File Commands Edit Menu and Editor Commands

o Outlining Menuo Advanced Menuo Selecting Text Commands

View Menu Project Menu and Project Commands

Debug Menu and Debug Commands Flash Menu Peripherals Menu Tools Menu SVCS Menu Window Menu Help Menu

C REATING APPLICATIONS

Home Creating Applications

This chapter describes the Build Mode of Vision3 and is grouped into thefollowing sections:

Create a Project : explains the steps required to setup a simple applicationand to generate HEX output.
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Project Target and File Groups : shows how to create application variantsand organized the files that belong to a project.

Tips and Tricks : provides information about the advanced features of theVision3 Project Manager.

C REATE P ROJECT

Home Creating Applications Create Project

Vision3 is a standard Windows application and started by clicking on theprogram icon. About the Environment describes the different window areas of Vision3.

Vision3 includes a project manager which makes it easy to design applicationsfor an ARM based microcontroller. You need to perform the following steps to createa new project:

Select the Toolset (only required for ARM Projects). Create Project File and Select CPU. Project Workspace - Books. Create New Source Files. Add Source Files to the Project. Create File Groups. Set Tool Options for Target Hardware. Configure the CPU Startup Code. Build Project and Generate Application Program Code. Create a HEX File for PROM Programming .

The section provides a step-by-step tutorial that shows you how to create asimple Vision3 project.

P ROJECT T ARGETS AND F ILE G ROUPS

Home Creating Applications Project Targets and File Groups

By using different Project Targets Vision3 lets you create several programsfrom a single project. You may need one target for testing and another target for arelease version of your application. Each target allows individual tool settings withinthe same project file.

Files Groups let you group associated files together in a project. We havealready used file groups in our example to separate the CPU related files from other
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