DESIGN AND CONSTRUCTION OF ELECTRONIC SIGN POST.

BY

A PROJECT SUBMITTED TO THE DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING

TECHNOLOGY

ABIA STATE POLYTECHNIC, ABA

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE NATIONAL DIPLOMA (ND) IN

ELECTRICAL /ELECTRONIC ENGINEERING

January, 2016

CERTIFICATION

This is to certify that this project research “DESIGN AND CONSTRUCTION OF MOVING LED DISPLAY BOARD” was carried out by

with matriculation numbers

DECLARATION

I hereby declare that this project “DESIGN AND CONSTRUCTION OF ELECTRONIC SIGN POST was designed and constructed by me to the Department of Electrical Electronic Engineering Abia State Polytechnic, Aba in partial fulfillment of the requirement for the award of National Diploma (ND) I further declare that this work has not been submitted to this or any other institution for the award of degree, diploma or equivalent course.

ACKNOWLEDGEMENT

My profound gratitude goes to my parents Mr and Mrs ………… for their invaluable contribution to my educational pursuit and every others sector of life.

My warm regards goes to my elder brother, ---------. for his support and various suggestions during the writing of this project, and to my younger siblings, Eunice and Prosper for their love and understanding.

I also want to appreciate the efforts of my friends and well wishers who in one way or the other contributed to my happiness and sustenance during my stay in school.

To my supervisor Engr for his instructions, my lecturers; for their numerous teachings and impartation in my life, while an undergraduate.

And not forgetting Consort for providing me with some of the materials needed for the write up of this project and for his coaching.

Thanks to you all.

ABSTRACT

This project focuses on the design and construction of a micro controller based moving message display. However, since the dot matrix technology is inevitably the underlying principle of the display system, much attention is focused on it and emphasis is centered on its streaming effect which employs the scanning method of displaying information under the hard wired system using the dot matrix arrangement of light emitting diodes in rows and columns. These light emitting diodes which form a hardware part of the system, provide a suitable way of displaying the information, radiating light in a specific color (red). The hard ware structure is interfaced with a programmed microcontroller in order to achieve the desired information.

TABLE OF CONTENT

CHAPTER ONE

INTRODUCTION

1.1 Brief Over View

1.2 Aim And Objectives

1.3 Statement Of Problem

1.4 Work Organization.

CHAPTER TWO

LITERATURE REVIEW

2.1 History of ELECTRONIC SIGN POST

CHAPTER THREE

DESIGN METHODOLOGY AND ANALYSIS

3.1 Introduction

3.2 Power Supply Unit

3.3 The Control Unit

3.4 Line Decoders

3.5 Formation of Character Font On The Display

3.6 Construction

3.7 Micro Controller Program

3.8 A51 Macro Assembly

3.9 Assembling With A51

CHAPTER FOUR

SYSTEM SOFTWARE

4.1 Operation

4.2 control system testing

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.1 Conclusion

5.2 Recommendation

5.3 Reference

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Recently there has been major advancement in technology. Thee advancement

have spurred to virtually every sector of life. The advertisement industry is no

exclusion. Today sign post and even sign boards have been gradually replaced

by electronic displays which are more attention catching and flexible.

The flashing message display is an electronic system which uses a series of

LEDs (light emitting diodes) to display messages in a flashing pattern.

Generally, such messages were scrolled so that they flash either from the left to

right or vice versa.

However, the LEDs cannot do that alone, thus for full functionality of the

flashing display system, the LEDs are connected to either computer or micro –

controller which is the major brain behind the formation and movement of

message letter or figures. Moreover, the computer or micro – controller needs

the aid of line decoders, crystal oscillators, semi conductors components such as

transistors, resistors and switches and the power supply unit for proper

implementation.

In this work, we shall be focusing in the design and construction of a flashing

message which will display 66 characters at a time, each consisting of 66 x 7

LEDs.

The messages display system will then display the message, “ELECTRICAL

ELECTRONICS ENGINEERING STUDENT WELCOMES, YOU TO ABIA

STATE POLYTECHNIC, MOTTO: EMPOWERING TECHNOLOGICAL

MINDS

1.2 AIMS AND OBJECTIVE

The aims and objectives of these projects are as follows:

To realize an electronic display system which has some level of

flexibility in its operations that is erasing and re – programming the

content stored in the memory to vary the display output is possible.

To implement in system, whose materials and components used in the

design of the hardware are sample and cheap and easily available in the

local market, thus making the whole system to be simple or design and

reducing cost.

To implement open module architecture that can be easily upgraded to

suit the specification of producers and manufacturers.

To make a system operations more appreciable by making the system re

– programmable.

To employ dot matrix arrangement on the display unit so as to allow

ease in expansion of both width and length of the display board.

To design a system which has human – machine inter – face in the

operations, completing transparent and applicable to end – users

1.4 WORK ORGANIZATIONThis work presents the design and construction of a re-programmable electronic flashing message display system using dot matrix arrangements of LEDs. This is presented through hard wiring which gives a faster response when arranged in modular configuration, which introduces some level of convenience to the designer. Chapter one discusses the background information of micro re-programmable digital display. Chapter two tells the literature review, chapter three describes the design and methodology,. Chapter four is the concluding chapter which also proffers future recommendations.

CHAPTER TWO

LITERATURE REVIEW

2.1 HISTORY OF ELECTRONIC SIGN POST

ELECTRONIC MESSAGE DISPLAY SIGNS

OverviewWe are all very fortunate to live in a society that places a premium value onFreedoms, and limits governmental intrusion upon those freedoms. Freedom ofSpeech is one of those essential freedoms, and one that is embodied within theConstitution that molds the rule of law governing this great nation. Manyreputable organizations, like the U.S. Small Business Administration and theInternational Sign Association caution against sign regulations that interfere withthe freedom of exercising commercial speech.The following information has been assembled by a coalition of manufacturers ofelectronic message display signs. We recognize the uncertainty surrounding thelegality of certain sign regulations. We also respect the desire by communities toregulate signs, including electronic message display signs, and the need forresponsible sign codes. Without engaging in debate over the legality ofregulations affecting electronic message displays, the following materials areintended to develop a more sophisticated understanding of the current state of thetechnology, and to promote regulations that reflect the broad variations in the use

of electronic message displays.

The History of ELECTRONIC MESSAGE DISPLAY SIGNS

In the day when signs were primarily painted, changing messages on a signmerely required painting over the existing message. More recently, signs withremovable lettering made it possible to manually change the lettering on a sign todisplay a new message. Electrical changeable message signs followed theinvention of the light bulb, and included light bulbs arranged in a pattern where,by lighting some light bulbs and not the others, letters and numerals could bespelled out.With the advent of solid-state circuitry in the early 1970s, electronic changeablemessage signs became possible. The first of these products were time andtemperature displays and simple text message displays using incandescent lamps.These lamps were very inefficient. They used a great deal of power and had shortlife expectancies.During the energy crunch of the 1980s, it became necessary to find ways toreduce the power consumption of these displays. This need initially spawned areflective technology. This technology typically consisted of a light-reflectivematerial applied to a mechanical device, sometimes referred to as “flip disk”displays. Electrical impulses were applied to a grid of disks with reflective materialon one side of the disk, and a contrasting finish on the other side. The electricalimpulses would position each disk within the grid to either reveal or conceal thereflective portion of the device as required, to produce an image or spell out amessage. These technologies were energy efficient, but due to the mechanicalnature of the product, failures were an issue. Shortly after the introduction of the reflective products, new incandescent lamps emerged. The new “wedge base” Xenon gas-filled lamps featured many positive qualities. Compared to the larger incandescent lamps that had been used for several years, the wedge base lamps were very bright, required less power to operate and had much longer lifetimes. These smaller lamps allowed electronic display manufacturers to build displays that featured tighter resolutions, allowing users to create more ornate graphic images.Next in the evolution of the changeable message sign was the LED. LED (lightemitting diode) technology had been used for changeable message displays sincethe mid 1970s. Originally, LEDs were available in three colors: red, green andamber, but were typically used for indoor systems because the light intensity was

insufficient for outdoor applications and the durability of the diodes suffered in thechanging temperatures and weather conditions. As technology improved,manufacturers were able to produce displays that had the intensity and long liferequired for outdoor use, but were limited in the viewing angle from which theycould be effectively seen. Recently, breakthroughs in this field have made available high intensity LEDs in red, green, blue and amber. These LEDs have made it possible to produce displays bright enough for outdoor use with viewing angles that are equal to, or better than, other technologies currently available. They are energy-efficient, can be programmed and operated remotely, and require little maintenance. In addition, the computer software has evolved such that a broad range of visualeffects can be used to display messages and images. The spacing of the LEDs canbe manipulated to achieve near-television resolution. Earlier “flip disk” and incandescent technologies have become nearly obsolete as a result.

Types of Electronic Message Display Signs

Electronic message display sign been placed into two basic categories: manually changedand electronically-changed. The most common form of manually changedsign involves a background surface with horizontal channels. Letters andnumerals are printed on individual plastic cards that are manually fitted into thechannels on the sign face. A broad range of letter styles and colors are available.The manually-changed sign is relatively inexpensive and is somewhat versatile.Some discoloration has been experienced in the background surface materialswith exposure to weather and the sun. Changing the message on such a sign isaccomplished by having an employee or technician remove the existing plasticletter cards and replacing them with cards displaying the new message.Occasionally, such signs have been the subjects of vandals who steal the letters or,as a prank, re-arrange them to spell out undesirable messages. Over time, asletters are replaced with lettering styles that deviate in color or type style from theoriginal set, such signs have had a tendency to take on a mix-and-matchappearance. Electronic message signs are generally of two types: light emittingand light reflective. Current light emitting display technologies include LED andincandescent lamp. Light reflective displays typically consist of either a reflectivematerial affixed to a mechanical device (like a “flip disk”) or a substance

commonly referred to as electronic ink. Many of the above mentioned technologies have the capabilities to display monochromatic (single color) or multiple color images. Monochrome changeable message signs are typically used to display text messages. Multiple color displays are more common in applications where color logos or video is displayed.

Operational Capabilities of Electronic Signs

Electronic signs have evolved to the point of being capable of a broad range ofoperational capabilities. They are controlled via electronic communication. Textand graphic information is created on a computer using a software program. Thissoftware is typically a proprietary component that is supplied by the displaymanufacturer. These software programs determine the capabilities of the displays.The software is then loaded onto a computer that operates the sign. Thecomputer may be installed within the sign itself, operated remotely from a nearbybuilding, or even more remotely by a computer located miles away and connectedto the sign with a telephone line modem or other remote communicationtechnology. Since most of the software programs are proprietary, one can assume that each software program is slightly different. However, the capabilities that the program offer are all very similar. Changeable message sign manufacturers providesoftware that allows the end user to be as creative or as reserved as they like. Thesign can be used to display static messages only, static messages changed by acomputer-generated transition from one message to the next, moving text,animated graphics and, in some applications, television-quality video.Text messages or graphic images can simply appear and disappear from thedisplay or they can be displayed using creative entry and exit effects andtransitions.

Example Oftentimes a display operator will choose to have a text message scroll onto the display and then “wipe-off” as if the frame has been turned like the page of a book. If a display has the capabilities to display graphics, logos or even video, it is common for the display operator to add motion to these images.

Example: A display operator at a school may wish to create an animation where theirschool’s mascot charges across a football field and runs over the competing

school’s mascot. Video-capable displays can operate much like a television. These displays can show live video, recorded video, graphics, logos, animations and text.All display capabilities are securely in the hands of the display operators. They areultimately responsible for what type of, and how, information is displayed on theirchangeable message sign.

Traffic Safety Considerations

Electronic message displays (EMDs) are capable of a broad variation ofoperations, from fully-static to fully-animated. In exterior sign use, they are oftenplaced where they are visible to oncoming traffic. Concerns are often raised ascommunities change their sign codes to expressly permit such signage about thetraffic safety implications for signage with moving messages. These concerns arelargely unfounded. EMDs have been in operation for many years. As is typical with many technological advances, the regulatory environment has been slow to respond to advances in the technology itself. In 1978, after many years of the use ofelectronic signs, Congress first passed legislation dealing with the use ofilluminated variable message signs along the interstate and federal aid primaryhighway system. The Surface Transportation Assistance Act permitted electronicmessage display signs, subject to state law, provided each message remainedfixed on the display surface but “which may be changed at reasonable intervals byelectronic process or remote control,” and did not include “any flashing,intermittent or moving light or lights.” 23 U.S.C. § 131.In 1980, and in response to safety concerns over EMDs along highways, theFederal Highway Administration published a report titled “Safety andEnvironmental Design Considerations in the Use of Commercial Electronic Variable-

Message Signs.” This report was an exhaustive analysis of the safety implicationsof EMDs used along highways. The report highlights the inconclusive nature ofsafety studies that had occurred to that time, some concluding that roadside signsposed a traffic distraction, and others concluding that roadside signs do not cause

traffic accidents. In view of the inevitable use of the technology in signage, thereport made some sensible observations about traffic safety considerations forsuch signs:

1. Longitudinal location. The report recommended that spacing standardsbe adopted to avoid overloading the driver’s information processingcapability. Unlike the standard for sign regulations in 1980, mostcommunities today have spacing standards already integrated into theirsign codes.

2. Lateral location. Often referred to as “setback,” the report initiallyrecommended the common sense requirement that such signs beplaced where the risk of colliding into the sign is eliminated. This was alegitimate concern, as such signs were being contemplated for use byhighway departments themselves in the right-of-way. Private use ofroadside signs is generally limited to locations outside the right-of-way,so this should not be a significant concern. The next issue addressed bythe report was visibility. The report advocated the minimum setbackfeasible, stating that “standards for lateral location should reduce thetime that drivers’ attention is diverted from road and traffic conditions.Generally this suggests that signs should be located and angled so as toreduce the need for a driver to turn his head to read them as heapproaches and passes them.” This can best be handled by permittingsuch signs to be located at the property line, with no setback, andangled for view by oncoming traffic.

3. Operations: Duration of message on-time. The report states that theduration of the message on-time should be related to the length of themessage, or in the case of messages displayed sequentially, themessage element. For instance, based on state highway agencyexperience, “comprehension of a message displayed on a panel ofthree lines having a maximum of 20 characters per line is best when theon-time is 15 seconds. In contrast, the customary practice of signingwhich merely displays time and temperature is to have shorter on-timesof 3 to 4 seconds.” Since this 1980 report, state highway agencies haveadopted, for use on their own signs, informal standards of considerablyshorter “on” time duration, with no apparent adverse effects on trafficsafety. Federal legislation affecting billboard use of electronic signsrequires only that messages be changed at “reasonable intervals.”1Moreover, the U.S. Small Business Administration, in a report on itswebsite reviewing safety information compiled since the 1980 report,has concluded that there is no adverse safety impact from the use of

EMD signs. The most recent study was performed in 2003 by Tantala ConsultingEngineers, available through the U.S. Sign Council at also concluding based on fieldstudies that EMD signs do not adversely affect traffic safety. Many smallbusinesses using one-line EMD displays are only capable of displayinga few characters at one time on the display, changing frequently, whichtakes virtually no time for a driver to absorb in short glances. Thesesigns have likewise not proven to be a safety concern, despite manyyears of use.

4. Operations: Total information cycle. EMD signs can be used to displaystand-alone messages, or messages that are broken into segmentsdisplayed sequentially to form a complete message. As to thesequential messages, the report recommended a minimum on-time foreach message “calculated such that a motorist traveling the affectedroad at the 85th percentile speed would be able to read not more thanone complete nor two partial messages in the time required toapproach and pass the sign.”

5. Operations: Duration of message change interval and off-time. Thereport defines the message change interval as the portion of thecomplete information cycle commencing when message “one” fallsbelow the threshold of legibility and ending when message “two” in asequence first reaches the threshold of legibility. This is relevant whenoperations such as “fade off-fade on” are used, when the first messagedissolves into the second message, or when the two messages movehorizontally (traveling) or vertically (scrolling) to replace the firstmessage with the second. Off-time, on the other hand, is a messagechange operation that involves the straightforward turning off of the firstmessage, with a period of blank screen, before the second message isinstantly turned on. The appropriate interval of message change may be affected by a variety of factors, and one standard does not fit all situations. Imagine, for instance, a bridge that serves two roadways, one with a speed limit of 30 mph and the other a highway with a speed limit of 60 mph. In a situation where the bridge is socked in by fog, an electronic sign on the approach to the bridge may be used to convey the message, “Fog ahead…onbridge…reduce speed…to 15 mph.” The driver on each roadway needs to see all the segments to the full message. The rate of changing each segment of the message needs to be different for each roadway. If the change rate were based only on the 60 mph speed, the sign on the slower roadway may appear too active. If the change rate were based only on the 30 mph speed, the result could be fatal to drivers on the highway. The report takes an extremely conservative

approach as to message change interval, advising against the use of operations other than nearly instantaneous message changes. If such operations are permitted, the report suggests “that the figure commonly used as ameasure of average glance duration, 0.3 second, be used here as amaximum permissible message change time limit.” The report furtheradvocates minimizing off-time between messages, where static messagechanges are used, stating that “[a]s this interval of off-time islengthened, the difficulty of maintaining the continuity of attention andcomprehension is increased.”The conservative nature of the authors’ position is reflected both in thereport, and in over twenty years of practice since the report was issued.The report cites studies indicating that, in some situations, the use ofelectronic operations had a beneficial effect on traffic safety, by creatinga more visually-stimulating environment along an otherwise mindnumbingsegment of highway, helping to re-focus and sharpen the driver’s attention to his or her surroundings.In over twenty years of experience, with numerous electronic signsnationwide utilizing the various operational capabilities for messagechange, there has been no significant degradation to highway safetyreported. Many electronic signs used by highway departments now usea mode of transition between messages or message segments, such astraveling or scrolling. Drivers are apparently capable of attachingprimacy to the visual information most critical to the driving task, withsign messages taking a secondary role.The report further expresses its limited focus upon interstate and federalaid primary highways. Noting the stimulating visual environmentcreated by full-animation signage in places like Times Square, LasVegas and Toronto’s Eaton Centre, the authors of the report agreed thatsuch signs added vitality and dimension to the urban core, butdiscouraged the use of animation alongside the highway. The reportdid not deal with the use of such signs, or their operationalcharacteristics, on roadways between the extremes of the interstatehighway and the urban core. In addition, animation has now beenused on highway-oriented signs in many locations for years, with noreported adverse effect of traffic safety.In sum, the report acknowledged the appropriateness of full-animationelectronic signs within the urban core, but recommended that full-animationnot be used along interstate and primary highways. It took a conservativeposition on operations of such signs along highways, advocating staticmessage change sequences only, with no more than 0.3 seconds of messagechange interval or “off-time” between messages. The message changes onsequential segmented messages should be displayed such that a motorist cansee and read the entire chain of message segments in a single pass.

Messages should be permitted to change at “reasonable intervals.” Such signsshould have adequate spacing between signs, but be set back from the right of-way as little as feasible.Since 1980, no new information has become available supporting a trafficsafety concern about EMDs. They have been installed in highway locations,along city streets and in urban core settings, using all forms of operations:static, sequential messaging and full animation. Despite such widespread use,and the presence of environmental organizations generally adverse to signdisplays, no credible studies have established a correlation between EMDs anda degradation in traffic safety.An article in the Journal of Public Policy and Marketing in Spring, 1997, arrived at the same conclusion. Professor Taylor, of Villanova University, analyzing this lack of data to support such a correlation, concluded that “there appears to be no reason to believe that changeable message signs represent a safety hazard.”From a safety standpoint, and based on the studies and practical experiencethat has been accumulated since the widespread use of EMDs, some conclusions can be reached:• In an urban core setting, where a sense of visual vitality and excitement isdesirable, full-animation EMDs have been shown to be viable withoutdegrading traffic safety.• In an urban setting, such as along arterial streets, EMDs have been usedwith static messages changed by use of transitions such as traveling,scrolling, fading and dissolving, without any apparent impact on trafficsafety. Quite likely, this can be attributed to the primacy of the navigationtask, and the secondary nature of roadside signage.• Along interstate and other limited access highways, the only significanttraffic safety analysis recommends the use of static messages only, and thefederal government permits message changes at “reasonable intervals.”Many highway departments change messages on their own signs every 1-2seconds. The report further recommends that sequential messages betimed to ensure that the entire sequence of messages be displayed in thetime it takes a car to travel from initial legibility to beyond the sign. Inpractice, and in the 20+ years since publication of this report, theoperational characteristics of such signs have been expanded to includefading, dissolving, scrolling and traveling, without any apparent adverseeffect on traffic safety.

Regulation of Electronic Signs Board

The history of the regulation of electronic signs has been largely marked by polar

extremes in regulation. A number of zoning and sign codes have treated suchsigns as any other sign, with no special regulations. Others have attempted toprohibit their use in the entirety, largely out of concerns for traffic safety, and insome cases in the stated interest of aesthetics.For the reasons stated above, the traffic safety concerns have been largelyunfounded. In decades of use and intense scrutiny, no definitive relationshipbetween electronic signs and traffic accidents has been established. In fact, some studies have suggested that animated electronic signs may help keep the driver whose mind has begun to wander re-focused on the visual environment in and around the roadway. No studies support the notion that an electronic sign with a static display has a visual impact, from either a traffic safety or aesthetic impact, different from that of any other illuminated sign.Despite this, the fear of negative impact from potentially distracting signs has inthe past motivated some communities to attempt to prohibit electronic signsaltogether. Two common approaches have been to prohibit sign “animation” and the “intermittent illumination” of electronic signs. Both approaches have had their limitations.Electronic signs that are computer-controlled often have the capability to bedisplayed with a multitude of operational characteristics, many of which fall within the typical definition of “animation.” However, static display techniques are quite commonplace with electronic signs, and the cost of using electronics in relatively typical sign applications has become more affordable. The programming of an electronic sign to utilize static displays only is simple and straightforward, yet probably overkill in the legal and practical sense.Nonetheless, out of fear that the programming may be changed to animationafter a sign is permitted and operational, some local regulators have attempted to take the position that LED and other electronic signs are prohibited altogether.This position is unsound. There is no legal basis to deny a static-display electronic sign, as it is legally indistinguishable from any other illuminated sign. We don’t prohibit car usage merely because the cars are designed so that they can exceed the speed limit; we issue a ticket to the driver if they do exceed the speed limit.Likewise, if a sign owner actually violates the zoning or sign code, the remedy is to cite them for the violation, not to presume that they will do so and refuse to issue permits at the outset. Moreover, most communities permit changing messages on signs displaying time and temperature, with no restrictions on timing. To apply a different standard to signs displaying commercial or noncommercial messages would be to regulate on the basis of the content of the sign, in violation of the First Amendment to the U.S. Constitution.The code technique of prohibiting “intermittent illumination” has its own limitations as it relates to electronic signs. The term “intermittent” suggests that the sign is illuminated at some times, and not illuminated at others. This is no

basis to distinguish between an electronic sign and any other illuminated sign. Virtually all illuminated signs go through a cycle of illumination and non-illumination, as the sign is turned off during the day when illumination is not needed, or during the evening after business hours. If this were the standard, most sign owners would be guilty of a code violation on a daily basis.Other terminology may be used in sign codes, but the fact is that a regulationmust be tailored to the evil it is designed to prevent. Community attitudes toward viewing digital images have changed nationwide, with personal computer use and exposure to electronic signs becoming widespread. People are simply accustomed to the exposure to such displays, more so than in years past. In some communities, there remains a concern about the potential that such signs may appear distracting, from a safety or aesthetic standpoint. Yet, static displays do not have this character, and even EMDs with moving text have not proven to have any negative impact. The real focus should be on the operations used for the change in message, and frame effects that accompany the message display.Many of these transition operations and frame effects are quite subtle, orotherwise acceptable from a community standpoint. It is now possible to definethese operations, in the code itself, with sufficient specificity to be able to enforce the differences between what is acceptable and what is not.The critical regulatory factors in the display of electronic changeable messagesigns are: 1) Duration of message display, 2) Message transition, and 3) Frameeffects. With the exception of those locations where full animation is acceptable, the safety studies indicate that messages should be permitted to change at “reasonable intervals.” Government users of signs have utilized 1-2 seconds on their own signs as a reasonable interval for message changes, and other communities permit very short display times or continuous scrolling on business signs without adverse effect. As a policy matter, some communities have elected to adopt longer duration periods, although to do so limits the potential benefits of using an electronic sign, particularly where messages are broken down into segments displayed sequentially on the sign.The message transitions and frame effects are probably the greater focus, from asign code standpoint. It is during the message transition or frame effect that theeye is most likely drawn to the sign. What is acceptable is a matter of community attitude. Flashing is a frame effect that is prohibited in many communities, but other more subtle transitions can be accepted. It is relatively easy to define four basic levels of operational modes for message transitions that can be incorporated into a sign code:Level 1 Static Display Only (messages changed with no transition)Level 2 Static Display with “Fade” or “Dissolve” transitions, or similarsubtle transitions and frame effects that do not have theappearance of moving text or images.Level 3 Static Display with “Travel” or “Scrolling” transitions, or

similar transitions and frame effects that have text oranimated images that appear to move or change in size, or berevealed sequentially rather than all at onceLevel 4 Full Animation, Flashing and VideoThere are, in fact, other operations recognized within the industry. However, inpractice they can be equated in visual impact with “fade,” “dissolve,” “travel” or “scrolling,” based on their visual effect, or otherwise be considered full animation. Different transition operations may be acceptable in different locations. For example, communities like Las Vegas accept full animation as a community standard, whereas others accept full animation only in urban core locations where a sense of visual vitality and excitement is desirable. Some communities may desire not to have an area with such visual stimuli, and elect to prohibit animation everywhere. However, in such a community, fade or scrolling may be acceptable forms of message transitions for static displays. In the most conservative communities, static displays with no observable transition between messages may be the only acceptable course.The next decision point for a community seeking to regulate electronic signs isProcedural. Some signs may be acceptable always, while the community mayDetermine that others are acceptable only in certain given circumstances.Alternatives to be considered for a sign code are as follows:• Permit electronic signs “as a matter of right”• Permit electronic signs with certain transitions “as a matter of right”• Permit electronic signs, subject to a review procedure• Permit electronic signs, with certain transitions, subject to a review

Procedure• A hybrid of the aboveFor instance, one community may find it acceptable to permit electronic signs, with full animation, as a matter of right. Other than a straightforward sign permit, no other review is required. In another community, the sign code structure may permit: 1) Static displays with no transitions as a matter of right, 2) Static displays using fade or dissolve transitions as a matter of right in certain commercial zoning districts, 3) Static displays using travel and scrolling transitions and animations incertain commercial districts, subject to approval of a special use permit, where the approving board can consider compatibility with surrounding land uses and attach conditions on the rate of message changes,

4) Fully-animated/video displays in the downtown commercial district only, subject to approval of a special use permit. The level of procedure involved should be tailored to the acceptance level of the community, and the resources available should public review be desired.In the following section, we have provided model code language that can beused, for reference, to incorporate into a community’s sign code. The modellanguage suggests code scenarios based on each of the four levels of displaytransitions. It also provides alternative language, for some scenarios, to eitherincorporate a special review procedure or not. Of course, the model languagemust be tailored to a particular community’s sign code. Variation may benecessary, where, for instance, the special review procedure would be by the local planning commission, city council or design review board. With ease, the model code language can be modified to meet local conditions.

Definitions

ELECTRONIC MESSAGE DISPLAY – A sign capable of displaying words, symbols, figures or images that can be electronically or mechanically changed by remote or automatic means.Electronic Message Displays may be permitted [with the approval of a usepermit] [in the zoning districts] subject to the following requirements:

a. Operational Limitations. Such displays shall contain static messagesonly, and shall not have movement, or the appearance or opticalillusion of movement, of any part of the sign structure, design, orpictorial segment of the sign, including the movement or appearance ofmovement of any illumination or the flashing, scintillating or varying oflight intensity.

b. Minimum Display Time. Each message on the sign must be displayedfor a minimum of (insert reasonable interval) seconds.

c. Message Change Sequence. [Alternative 1: The change of messagesmust be accomplished immediately.] [Alternative 2: A minimum of 0.3seconds of time with no message displayed shall be provided betweeneach message displayed on the sign.]

Model Electronic Sign Code ProvisionsLevel 2-Static Display (Fade/Dissolve Transitions)

DISSOLVE – a mode of message transition on an Electronic Message Displayaccomplished by varying the light intensity or pattern, where the first message

gradually appears to dissipate and lose legibility simultaneously with the gradual appearance and legibility of the second message.

FADE – a mode of message transition on an Electronic Message Displayaccomplished by varying the light intensity, where the first message graduallyreduces intensity to the point of not being legible and the subsequent messagegradually increases intensity to the point of legibility.

FRAME – a complete, static display screen on an Electronic Message Display.

FRAME EFFECT – a visual effect on an Electronic Message Display applied to a single frame to attract the attention of viewers.

TRANSITION – a visual effect used on an Electronic Message Display to change from one message to another.

Level 3-Static Display (Travel/Scroll Transitions and Animations)

SCROLL – a mode of message transition on an Electronic Message Display where the message appears to move vertically across the display surface.

TRANSITION – a visual effect used on an Electronic Message Display to change from one message to another.

TRAVEL – a mode of message transition on an Electronic Message Display where the message appears to move horizontally across the display surface.

CHAPTER THREE

DESIGN METHODOLOGY AND ANALYSIS

3.1 INTRODUCTION

This project is designed so as to realize an efficient, maintainable, and most importantly, affordable electronic re-programmable display system using dot matrix technology. The moving message display system is designed in modules, which involves the techniques of modularity. For simplicity, the suitability and compatibility of a stage to conform to the changing circuit parameters in other stages were considered. Another important step taken was early identification of

hazards and the development of appropriate steps to isolate and control them in the design phase. The different section/modules that make up the whole system are shown below.

Block diagram of a Micro programmable moving message display system

showing its principle of operation.

3.2 THE POWER SUPPLY UNIT

The power supply unit is a system that supplies electrical or other types of energy to an output or group of loads.

The power supply unit is a system that supplies voltage to all parts of a circuitry. There are basically two main types of power supplies – linear power supply and switched mode power supply.

In this project, the linear power supply was used principally the linear power supply consists of four sections. Complete implementation. They include:

CONTROL UNIT

TRANSFORMER RECTIFIER FILTER REGULATOR

1. Transformation2. Rectification3. Filtration4. Regulation

A typical block diagram of the linear power supply unit is as shown below.

Block diagram of the power supply unit

THE TRANSFORMER

In this project, a 240/12V, 500MA based transformer is used based on the fact that the means supply is rated at 240V and the actual voltage required by the circuit components (micro – controller, line decoder LEDs etc.) is a regulated 5V

However, a 7805 regulator is used which required a minimum of 8V. The back drop voltage from the regulator is 1.4v given a total of 9.4V. The 12V transformers are available. A current of 500mA is sufficient to drive all the circuit components.

THE RECTIFIER

A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification.

Rectification can either be half wave or full wave.Half – Wave Rectification

In half – wave rectification, either the positive or negative half of the AC wave is passed, while the half of the other is blocked.

Full – Wave RectificationA full wave rectifier converts the whole of the input form if the inputs wave form to constant polarity at its output.

In this project, full wave bridge rectifier is used because it provides a better efficiency compared to half wave and bridge rectifier, because the transformer used not center tapped.

FILTERFilters are electronic circuit which perform signal processing functions, specifically to remove unwanted frequency component from the signal to enhance wanted ones or both. They consist of a capacitor connected across the rectified output for the purpose of smoothening out the unwanted ripple in the output. The capacitors basically store charges temporarily and the stored charges are measured in farad, micro – farad and pico – farad.

The RegulatorA voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. It may use an electromechanical mechanism, or passive or active electronic component. Depending on the design, it may be used to regulate one or more AC or DC voltages.

The voltage regulator used in this project is 78HC05 integrated circuit. It has three terminals and is capable of supplying 5+ 10% at 100Ma

1 3

U 1

78105

2

Circuit symbol of a voltage regulator with pin out indicator Terminal 1 serves as the input. 2 serves as ground and 3 as the input terminal.The 7805 used takes 12V from the transformer and gives output of 5V± 0.2%.

Power Indicator

Diode D5 is a light emitting diode used as power on indicator. This glows once power is on. Resistor R1 is a circuit-limiting resistor, which helps to limit the amount of current flowing through the diode D5.

The value of the limiting resistor is gotten by the expression.

Resistor R1 = (Vdc – Vd) Imax

Where: Vdc = the calculated dc voltage which is given byVdc = Vac √2 = 12* √2Vdc = 16.97

Vd = Diode voltage drop = 1.7V

I2 = Maximum circuit rating of the LED (D5) = 20Ma

Value of the limiting resistor becomes

R1 = 16.07 - 1.7 20 * 10

R1 = 763.5Ω

Therefore for safety reasons, a value of 1000Ω or 1KΩ which is a little higher than 763.5Ω is used to take care of inconsistencies.

3.3 THE CONTROL UNIT

The control unit is made up of a single micro controller chip that can execute a user program, normally for the purpose of controlling the device; the transistors serve as switches and the line decoders.

ATMEI 74154

The ATMEI 74154 is a single chip micro-controller that has random access memory (RAM) and read only memory (ROM). It has instruction set and is compatible with any other MC51 controller family.

The RAM (Random Access Memory) – This consists of 128 byte arranged as four register bank, each containing 8 registers given the label R0 to R7.

The ROM (Read Only Memory) – The 74154 has 4K bytes ROM. This portion of the 74154 is made available for the storage of program written by the system designer. The operation of the 74154 depends on the program. Serial Communication Ports/Pin Configuration- the 74154 micro-controller is a 40 pin IC with basically four communication ports with pin 20 and 40 as ground and voltage supply respectively. The four communication ports are ports are port 0, port 1, port 2 and port 3. This is illustrated in the fig below.

Diagram of 74154

ALE/PROG: Address latch enable output pulse latching the low byte of the address during accessory to external memory. ALE is emitted at a constant rate of 1/6 of the oscillator frequency for external timing or clocking purposes even when there are no accesses to external memory. This pin is also the program pulse input (PROG) during EPROM programming.

PSEN: Program store Enable is the read strobe to external program memory. When the device is executing out of external program memory, PSEN is activated twice each machine cycle (except that two PSEN activation are skipped during access to external Data Memory). PSEN is not activated when the device is executing out the internal program memory.

EA/VPP: When EA is held high, the CPU executes out of external program memory. Holding EA low forces the CPU to execute out of external memory regardless of the program counter value.

XTAL1: Input to the inventing oscillator amplifierXTAL2: Output from the inverting oscillator.

PORT 6: Port is an 8 bit drawn bi – directional port. As open drawn output port, it can sink eight LS TTL loads. Port ) pins that have 1s written to them float and in that state will function as high impedance inputs. Ports 0 is also the multiplexed lower – order and data bus during access program and data memory.

PORT 1: Port 1 is also 8 bit bi – directional I/O port with internal pull – ups. The port 1 output buffers can drive TTL inputs. Port 1 pins that have 1s written to them are pulled high by the internal pull – ups, and in that state can be used as inputs, ports 1 pins that are externally being pulled low will source current because of the internal pull – ups.

PORT 2: Port 2 is an 8 bit bi – directional I/O port with pull – ups. Port 2 emits the high order address byte during accesses to external memory that use 16 bit addresses.

PORT 3: Port 3 is an 8 bit bi – directional I/O port with internal pull ups.VCC: Supply voltageVSS: Circuit grounded potential

LINE DECODERS

Binary Decoder

It is basically, a combinational type logic circuit that converts the binary code data at its input into one of a number of different output lines, one at a time producing an equivalent decimal code at its output. Binary Decoders have inputs of 2-bit, 3-bit or 4-bit codes depending upon the number of data input lines, and a n-bit decoder has 2n output lines. Therefore, if it receives n inputs (usually grouped as a binary or Boolean number) it activates one and only one

of its 2n outputs based on that input with all other outputs deactivated. A decoder’s output code normally has more bits than its input code and practical binary decoder circuits include 2-to-4, 3-to-8 and 4-to-16 line configurations.

A binary decoder converts coded inputs into coded outputs, where the input and output codes are different and decoders are available to "decode" either a Binary or BCD (8421 code) input pattern to typically a Decimal output code. Commonly available BCD-to-Decimal decoders include the TTL 7442 or the CMOS 4028. An example of a 2-to-4 line decoder along with its truth table is given below. It consists of an array of four NAND gates, one of which is selected for each combination of the input signals A and B.

2-to-4 Binary Decoders

A binary decoder converts coded inputs into coded outputs, where the input and output codes are different and decoders are available to "decode" either a Binary or BCD (8421 code) input pattern to typically a Decimal output code. Commonly available BCD-to-Decimal decoders include the TTL 7442 or the CMOS 4028. An example of a 2-to-4 line decoder along with its truth table is given below. It consists of an array of four NAND gates, one of which is selected for each combination of the input signals A and B.

2-to-4 Binary Decoders

In this simple example of a 2-to-4 line binary decoder, the binary inputs A and B determine which output line from D0 to D3 is "HIGH" at logic level "1" while the remaining outputs are held "LOW" at logic "0" so only one output can be active (HIGH) at any one time. Therefore, whichever output line is "HIGH" identifies the binary code present at the input, in other words it "de-codes" the

binary input and these types of binary decoders are commonly used as Address Decoders in microprocessor memory applications.

Some binary decoders have an additional input labelled "Enable" that controls the outputs from the device. This allows the decoders outputs to be turned "ON" or "OFF" and we can see that the logic diagram of the basic decoder is identical to that of the basic demultiplexer. Therefore, we say that a demultiplexer is a decoder with an additional data line that is used to enable the decoder. An alternative way of looking at the decoder circuit is to regard inputs A, B and C as address signals. Each combination of A, B or C defines a unique address which can access a location having that address.

In this simple example of a 2-to-4 line binary decoder, the binary inputs A and B determine which output line from D0 to D3 is "HIGH" at logic level "1" while the remaining outputs are held "LOW" at logic "0" so only one output can be active (HIGH) at any one time. Therefore, whichever output line is "HIGH" identifies the binary code present at the input, in other words it "de-codes" the binary input and these types of binary decoders are commonly used as Address Decoders in microprocessor memory applications.

Some binary decoders have an additional input labelled "Enable" that controls the outputs from the device. This allows the decoders outputs to be turned "ON" or "OFF" and we can see that the logic diagram of the basic decoder is identical to that of the basic demultiplexer. Therefore, we say that a demultiplexer is a decoder with an additional data line that is used to enable the decoder. An alternative way of looking at the decoder circuit is to regard inputs A, B and C

as address signals. Each combination of A, B or C defines a unique address which can access a location having that address.

Sometimes it is required to have a Binary Decoder with a number of outputs greater than is available, or if we only have small devices available, we can combine multiple decoders together to form larger decoder networks as shown. Here a much larger 4-to-16 line binary decoder has been implemented using two smaller 3-to-8 decoders.

4-to-16 Binary Decoder ConfigurationInputs A, B, C are used to select which output on either decoder will be at logic "1" (HIGH) and input D is used with the enable input to select which encoder either the first or second will output the "1".

Binary Decoders are most often used in more complex digital systems to access a particular memory location based on an "address" produced by a computing device. In modern microprocessor systems the amount of memory required can be quite high and is generally more than one single memory chip alone. One method of overcoming this problem is to connect lots of individual memory chips together and to read the data on a common "Data Bus". In order to prevent the data being "read" from each memory chip at the same time, each memory chip is selected individually one at time and this process is known as Address Decoding.

In this application, the address represents the coded data input, and the outputs are the particular memory element select signals. Each memory chip has an

input called Chip Select or CS which is used by the MCU to select the appropriate memory chip and a logic "1" on this input selects the device and a logic "0" on the input de-selects it. By selecting or de-selecting each chip, allows us to select the correct memory device for a particular address and when we specify a particular memory address, the corresponding memory location exists ONLY in one of the chips.

In this project the work of 74ls138 is working as a master for chip selection its input is come from microcontroller and its output is used for chip selection its output is active low so as a low signal is applied on the 18 or 19 pin of 4*16 decoder it activated and get start working. When a port 1 value is 16 then first 74ls154 is disabled and other is enabled.

Here A0, A1, A2 and A3 are the inputs of the 74ls154. Its output is active low .E0 and E1 are two inputs for enabling the ic. I ground a pin 19 and pin 18 is controlled by the 74ls138 to enable it at a specific time. It should not be on at every time.

The 74138 line decoder is a high performance memory decoding or data-routing IC that requires a very short propagation delay times. The 74138 decodes one of the seven lines depending on the conditions at the three binary SELECT INPUTS and the three ENABLE INPUTS.

3.4 FORMATION OF CHARACTER FONT ON THE DISPLAY

Use of fonts.exeThis exe files can be used to generate a 7*5 (7 rows*5 column) fonts size pattern in hardware..In the above diagram row 6,7 and 8 has code 00h mean no display by using 8*8 just one 00h is used if use three 00h the gap is seems too much between two characters.Below is the screen shot of fonts.exe that how I use it, it has many formats and option to do as I check three boxes and then generate a font’s pattern code.

Dot matrix internal structure:

In the above diagram rows are supplied by 5 volt and ground provided at column then led glow.I am using the same pieces it is called common cathode configuration.

3.5 CONSTRUCTION AND OPERATION

3.5.1 CONSTRUCTION

The construction of the moving message display system was done in such a way that connections followed the circuit diagram. The LEDs were connected anode to anode and cathode to cathode in a 7 by 25 format so that the system can display 5 characters at a time, each comprising of 7 by 5 LEDs. Thus each letter is typified with 7 LEDs on the vertical axis and 5 LEDs on the horizontal axis.

The connection of LEDs is interfaced with the micro controller and four line decoders which control the display and movement of messages.The system’s internal circuit is connected in such a way that every unit except the transformer is mounted on the same circuit board. This was done to minimize the weight of the message display system. The casing is 2.5 ft by 6 ft. and a total number of 210 LEDs were used in order to display five letters at a time. A reddish translucent glass was used in order to make the display visible and at

3.6 COMPONENTS AND FEATURES

List of components part Quantity

RESISTOR 7

R1 1

R2 1

R3.1 – 8 8

CAPACITORS

C1 1

C2 1

C3 1

C4 1

TRANSISTORS

T1 – 8 8

LEDs 336

DECODER 1

ICs’ 3

AT89C51 Micro – controller 1

RESISTORSA resistor is a two terminal electronic component that produces a voltage across its terminals that is proportional to the electric current passing through it in accordance to ohms law.

TRANSISTORThis is a semi – conductor device commonly used to accomplish or switch electronic signals. A voltage or current applied to one pair of the transistor’s

terminals changes the current following through another pair of terminals changes the current following through another pair of terminal. The transistor provides an amplification of signal.

LIGHT EMITTING DIODES (LEDs)LEDs from the numbers on digital clock transmission from remote controls, light up watches, etc. They are tiny bulbs, but unlike ordinary incandescent bulb, they don’t filament that will burn off and they don’t get hot. They are illuminated solely by the movement of electron in a semi – conductor material and they last just as long as a standard transistor.

LINE DECODERSDecoders are collection of logical gates, which are arranged in a specific way so as to break down any combination of inputs to a set of terms that are all set to 0 apart from 1 term.

MICR-CONTROLLERThis is a single programmable chip that is designed to control circuits that are interfaced with it. They usually consist of ports and other activation pins having specific functions. There are of various families including the 8086, 8088, 8951 series.

INTEGRATED CIRCUIT also called microelectronic circuit or chip, an assembly of electronic components, fabricated as a single unit, in which miniaturized active devices (e.g., transistors and diodes) and passive devices (e.g., capacitors and resistors) and their interconnections are built up on a thin substrate of semiconductor material (typically silicon). The resulting circuit is thus a small monolithic “chip,” which may be as small as a few square centimeters or only a few square millimeters. The individual circuit components are generally microscopic in size.

CAPACITOR (originally known as a condenser) is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The nonconducting dielectric acts to increase the capacitor's charge capacity. A dielectric can be

glass, ceramic, plastic film, air, vacuum, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

CRYSTAL OSCILATOR

is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency.[1][2][3] This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators,[1] but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.

3.7 SYSTEM SOFTWARE

Micro- controllers ProgramIn this project, the program used is assembly language. Assembly language is a low key programming language that makes use of mnemonics or symbols to program the computer. This makes the assembly language user-friendly, since it is easier for a user to remember programming symbols which are far easier than complex machine codes. However, it employs a utility program that translates its symbols into a form that is readable by the computer’s machine. The assembly language is usually employed in the programming of computers, microprocessors, microcontrollers and even integrated circuits. They implement a symbolic representation of the numeric machine codes and other constants needed to program a particular CPU architecture. The utility program called the assembler is used translate assembly language into the target computer machine code. In this project however, the assembler used is the A51 Macro Assembler.

3.8 A51 MACRO ASSEMBLER The A51 assembler is an Intel ASM51-compatible macro assembler for the 8051 family of microcontrollers. The A51 assembler translates symbolic assembly language mnemonics into relocatable object code where utmost speed, small code size, and hardware control are critical. The macro facility speeds development and conserves maintenance time, because common sequences need be developed only once. The assembler supports symbolic access to all features of the 8051 and is configurable for each 8051 derivative. The A51

assembler translates an assembler source file into a relocatable object module. If the DEBUG control is used, or if the “Include debugging information” option is checked, this object file will contain full symbolic information for debugging with the WinSim-51 debugger/simulator or an in-circuit emulator. The A51 assembler generates a list file, optionally with symbol table and cross references. The A51 assembler is fully compatible with Intel ASM51 assembly programs.

3.9 Assembling with A51

This chapter explains how to use the A51 assembler to assemble 8051 assembly source files and discusses the assembler controls that you may specify on the command line and within the source file. Using the controls described in this chapter, you can specify which operations are performed by A51. For example, you may direct the A51 assembler to: generate a listing file, produce cross reference information, and control the amount of information included in the object file. You may also conditionally assemble sections of code using the conditional assembly controls.

3.10 Running the Assembler

First the ASSEMBLER is invoked by selecting TRANSLATE, MAKE, or BUILD ALL from the Project menu in preview. The TRANSLATE command will assemble only the source file that is selected in the project window. The MAKE command will compile and link all changed files in the project. The BUILD ALL command will compile, assemble and link all of the files in the project. To invoke the Assembler, you enter A51 at the DOS prompt. The command line must contain the name of the 8051 assembly source file to be assembled as well as any required command-line controls. The format for the A51 assembler command line is: A51 sourcefile controls… where sourcefile is the name of the source program you want to assemble. The A51 assembler controls are used to direct the operation of the assembler. Refer to the “Assembler Controls” section later in this chapter for more information.

CHAPTER FOUR

4.1 OPERATION

When the system is powered on, the powered supply unit provides the voltage (5V) necessary to power the micro controller, the LEDs and other circuit element. The micro – controller receives 5V from pin 1 with pin 20 grounded,

begins to execute programmes from its internal memory. As a result of this, data signals are sent from the micro – controller port 1 to the input pins of the eight line decoders and clock signals are sent to their clock input pin from port of the micro – controller. At the same time, base biased signals are sent to the bases of the transistors from the micro controller’s port 2.

Immediately the line decoder receives the clock signals from micro – controller, the decoders transfers their data to other output pins, which are connected to the cathode of the LEDs. Also when the transistors receive their base bias currents from the micro controller they switch power to the LEDs, since they are wired to the anode of the LED array. At this time, LED will only grow if its anode is positive with respect to the cathode. Thus, by controlling the system sent to the decoders and transistors, the micro – controller controls LED which needs to be on/off for the device to achieve the display.

SYSTEM INTEGRATIONUsually before a system is developed, other subsystems are brought together in such a way as to achieve a singular purpose. In this piece of work, the case is not different. Subsystems were designed and integrated to each other. The hardware and the software are interwoven to realize a desired result. They must be compatible for there to be a smooth protocol or receiving and processing of the information.

TEST PLANTo verify the functionality of various subsystems, a test plan is adopted. Here, we are using a module by module testing plan. This is necessary to ensure the smooth operation of the project work. The plan helps to detect any abnormality should there be any malfunctioning.

MODULE BY MODULE TESTING1. POWER UNIT TESTING: this unit comprises the transformer, bridge

rectifier, filtering capacitor and a voltage regulator. All electronic gadgets use a DC voltage source. In this work, TTL (Transistor Transistor Logic) was used, hence the need to use 5Volt source. The regulator 7805 stabilizes the DC voltage to +5V. At the end of the construction, the test was ok. This unit is very vital in any electronic circuit in that it supplies the required energy to each module.

2. DEMULTIPLEXERS AND LINE DECODERSIt operates on a principle of causing the output that corresponds to the binary input to go LOW. At each binary input, the output pins respond only if the enable pins are activated. The line decoder has a tristate

capability. Therefore its operation is dependent on the activation pins and the supply of the binary codes at the input pins.

3. PROCESSING UNIT TESTThis is tested based on its connection to other subsystems. It is the unit that establishes control over all other subsystems. The test has to include the software programs written to drive the hardware. More still, simulation software could be used to debug the program to verify its workability and compatibility to other modules.

4.2 CONTROL SYSTEM TESTINGThe control is provided by a microcontroller based on the software program burned into it. It is expected to switch each lamp at appropriate time and also switch them OFF when it is desired. After the design, the software drives the hardware as expected and is working quite well.

USER MANUAL AND PRECAUTIONIt is expected that the user must have read this manual before operating this system.

Operation procedure:1. Connect the mains plug to the mains.2. Switch ON the system3. Change the direction of the traffic by pressing the appropriate

button. Do not press any if you wish not to change the direction of traffic.

4. Do not open the casing to avoid electric shock. For services, take to a registered service personnel.

5. Switch OFF the system when it is not in use.

CHAPTER FIVE

RECOMMENDATION AND CONCLUSION

5.1 PROBLEMS ENCOUNTERED

In the course of carrying out this project, several problems were encountered

First, sourcing for materials was pretty difficult as most of the circuit elements could not be found in neighboring markets. Traveling out town to get them was the only solution.

Second, during the course of building, some components got damaged. Such damage could be allotted to over-heating during soldering, careless handling, environmental distortions and even incompetence of manufacturing.

Third, due to wrong connection on one occasion, a fault arose, leading to the demand for trouble shooting which was time consuming and stressful.

Fourth, due to my non conversance with this project, a lot of errors where registered in programming which had to be debugged for the program to run accurately.

5.2 RECOMMENDATIONS

The design of a micro controller based moving message display system has characters showing five pages at a time. There is a great need for future design and implementations to cater for animations and symbols.

Again, plasma display panels may be used in place of light emitting diodes to accommodate certain areas of our economy that may require large display board for advertisement.

There is significant need for future design to include a universal serial bus of a serial interface that was used for the same purpose.

5.1 CONCLUSION The digital electronic message display system has been modernized with sophisticated electronic devices, which center on the urgent needs in our advertising industry. They provide various applications in different aspects of our economy such as banks, airports, restaurants, superstores, institutions, entertainment, stock exchange market and directional venue guides.

The light emitting diodes which constitute of the hardware system is mainly used to display alphanumeric characters and symbols in various systems such as digital clocks, microwave ovens, stereo tuners and calculators.

The design of moving massage display systems have a single micro- controller chip which provides 8 kilobytes of flash, 256 of ram, 31 input/output lines, three 16 bit timer counters, six vector two-level interrupt architecture, full duplex serial port, on chip oscillator and clock that provides the necessary control and flexibility of display.

.

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