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1. 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
2. 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.
3. 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.
4. 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.
5. 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
6. 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
7. message letter or figures. Moreover, the computer or micro – controller needs
the aid of line decoders, crystaloscillators, semi conductors components suchas
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.
8. To design a system which has human – machine inter – face in the
operations, completing transparent and applicable to end – users
1.4 WORK ORGANIZATION
This 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 responsewhen 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.
9. CHAPTER TWO
LITERATURE REVIEW
2.1 HISTORY OF ELECTRONIC SIGN POST
ELECTRONIC MESSAGE DISPLAY SIGNS
Overview
We are all very fortunate to live in a society that places a premium value on
Freedoms, and limits governmental intrusion upon those freedoms. Freedom of
Speech is one of those essential freedoms, and one that is embodied within the
Constitution that molds the rule of law governing this great nation. Many
reputable organizations, like the U.S. Small Business Administration and the
International Sign Association caution against sign regulations that interfere
with
the freedom of exercising commercial speech.
The following information has been assembled by a coalition of manufacturers
of
electronic message display signs. We recognize the uncertainty surrounding the
legality of certain sign regulations. We also respectthe desire by communities
to
regulate signs, including electronic message display signs, and the need for
responsible sign codes. Without engaging in debate over the legality of
regulations affecting electronic message displays, the following materials are
intended to develop a more sophisticated understanding of the current state of
the
technology, and to promote regulations that reflect the broad variations in the
use
10. of electronic message displays.
The History of ELECTRONIC MESSAGE DISPLAY SIGNS
In the day when signs were primarily painted, changing messages on a sign
merely required painting over the existing message. More recently, signs with
removable lettering made it possibleto manually change the lettering on a sign
to
display a new message. Electrical changeable message signs followed the
invention 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 be
spelled out.
With the advent of solid-state circuitry in the early 1970s, electronic changeable
message signs became possible. The first of these products were time and
temperature displays and simple text message displays using incandescent
lamps.
These lamps were very inefficient. They used a great deal of power and had
short
life expectancies.
During the energy crunch of the 1980s, it became necessary to find ways to
reduce the power consumption of these displays. This need initially spawned a
reflective technology. This technology typically consisted of a light-reflective
material applied to a mechanical device, sometimes referred to as “flip disk”
displays. Electrical impulses were applied to a grid of disks with reflective
material
on one side of the disk, and a contrasting finish on the other side. The electrical
impulses would position each disk within the grid to either reveal or conceal the
reflective portion of the device as required, to producean image or spell out a
message. These technologies were energy efficient, but due to the mechanical
nature 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 (light
emitting diode) technology had been used for changeable message displays
since
the mid 1970s. Originally, LEDs were available in three colors:red, green and
amber, but were typically used for indoor systems because the light intensity
was
11. insufficient for outdoorapplications and the durability of the diodes suffered in
the
changing temperatures and weather conditions. As technology improved,
manufacturers were able to producedisplays that had the intensity and long life
required for outdooruse, but were limited in the viewing angle from which they
could 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 outdooruse 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 visual
effects can be used to display messages and images. The spacing of the LEDs
can
be 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
changed
and electronically-changed. The most common form of manually changed
sign involves a background surface with horizontal channels. Letters and
numerals are printed on individual plastic cards that are manually fitted into the
channels 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 materials
with exposure to weather and the sun. Changing the message on such a sign is
accomplished by having an employee or technician remove the existing plastic
letter 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, as
letters are replaced with lettering styles that deviate in color or type style from
the
original set, such signs have had a tendency to take on a mix-and-match
appearance. Electronic message signs are generally of two types: light emitting
and light reflective. Current light emitting display technologies include LED
and
incandescent lamp. Light reflective displays typically consist of either a
reflective
material affixed to a mechanical device (like a “flip disk”) or a substance
12. 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 of
operational capabilities. They are controlled via electronic communication. Text
and graphic information is created on a computer using a software program.
This
software is typically a proprietary componentthat is supplied by the display
manufacturer. These software programs determine the capabilities of the
displays.
The software is then loaded onto a computer that operates the sign. The
computer may be installed within the sign itself, operated remotely from a
nearby
building, or even more remotely by a computer located miles away and
connected
to the sign with a telephone line modem or other remote communication
technology. 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 provide
software that allows the end user to be as creative or as reserved as they like.
The
sign can be used to display static messages only, static messages changed by a
computer-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 the
display or they can be displayed using creative entry and exit effects and
transitions.
Example Oftentimes a display operator will chooseto 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 schoolmay wish to create an animation where
their
school’s mascotcharges across a football field and runs over the competing
13. 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
are
ultimately responsible for what type of, and how, information is displayed on
their
changeable message sign.
Traffic Safety Considerations
Electronic message displays (EMDs) are capable of a broad variation of
operations, from fully-static to fully-animated. In exterior sign use, they are
often
placed where they are visible to oncoming traffic. Concerns are often raised as
communities change their sign codes to expressly permit such signage about the
traffic safety implications for signage with moving messages. These concerns
are
largely 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 of
electronic signs, Congress first passed legislation dealing with the use of
illuminated variable message signs along the interstate and federal aid primary
highway system. The Surface Transportation Assistance Act permitted
electronic
message display signs, subject to state law, provided each message remained
fixed on the display surface but “which may be changed at reasonable intervals
by
electronic process orremote control,” and did not include “any flashing,
intermittent or moving light or lights.” 23 U.S.C. § 131.
In 1980, and in responseto safety concerns over EMDs along highways, the
Federal Highway Administration published a report titled “Safety and
EnvironmentalDesign Considerations in the Use of Commercial Electronic
Variable-
Message Signs.”This report was an exhaustive analysis of the safety
implications
of EMDs used along highways. The report highlights the inconclusive nature of
safety studies that had occurred to that time, some concluding that roadside
signs
posed a traffic distraction, and others concluding that roadside signs do not
cause
14. traffic accidents. In view of the inevitable use of the technology in signage, the
report made some sensible observations about traffic safety considerations for
such signs:
1. Longitudinallocation. The report recommended that spacing standards
be adopted to avoid overloading the driver’s information processing
capability. Unlike the standard for sign regulations in 1980, most
communities today have spacing standards already integrated into their
sign codes.
2. Laterallocation. Often referred to as “setback,”the report initially
recommended the common sense requirement that such signs be
placed where the risk of colliding into the sign is eliminated. This was a
legitimate concern, as such signs were being contemplated for use by
highway departments themselves in the right-of-way. Private use of
roadside signs is generally limited to locations outside the right-of-way,
so this should not be a significant concern. The next issue addressed by
the report was visibility. The report advocated the minimum setback
feasible, stating that “standards forlateral location should reduce the
time that drivers’ attention is diverted from road and traffic conditions.
Generally this suggests that signs should be located and angled so as to
reduce the need for a driver to turn his head to read them as he
approaches and passes them.” This can best be handled by permitting
such signs to be located at the property line, with no setback, and
angled for view by oncoming traffic.
3. Operations: Duration of message on-time. The report states that the
duration of the message on-time should be related to the length of the
message, or in the caseof messages displayed sequentially, the
message element. For instance, based on state highway agency
experience, “comprehension of a message displayed on a panel of
three lines having a maximum of 20 characters per line is best when the
on-time is 15 seconds. In contrast, the customary practice of signing
which merely displays time and temperature is to have shorter on-times
of 3 to 4 seconds.”Since this 1980 report, state highway agencies have
adopted, for use on their own signs, informal standards of considerably
shorter “on”time duration, with no apparent adverse effects on traffic
safety. Federal legislation affecting billboard use of electronic signs
requires only that messages be changed at “reasonable intervals.”1
Moreover, the U.S. Small Business Administration, in a report on its
website reviewing safety information compiled since the 1980 report,
has concluded that there is no adverse safety impact from the use of
15. EMD signs. The most recent study was performed in 2003 by Tantala
Consulting
Engineers, available through the U.S. Sign Council at also concluding based on
field
studies that EMD signs do not adversely affect traffic safety. Many small
businesses using one-line EMD displays are only capable of displaying
a few characters at one time on the display, changing frequently, which
takes virtually no time for a driver to absorb in short glances. These
signs have likewise not proven to be a safety concern, despite many
years of use.
4. Operations: Total information cycle. EMD signs can be used to display
stand-alone messages, or messages that are broken into segments
displayed sequentially to form a complete message. As to the
sequential messages, the report recommended a minimum on-time for
each message “calculated such that a motorist traveling the affected
road at the 85th percentile speed would be able to read not more than
one complete nor two partial messages in the time required to
approachand pass the sign.”
5. Operations: Duration of message changeinterval and off-time. The
report defines the message change interval as the portion of the
complete information cycle commencing when message “one” falls
below the threshold of legibility and ending when message “two” in a
sequence first reaches the threshold of legibility. This is relevant when
operations such as “fade off-fade on” are used, when the first message
dissolves into the second message, or when the two messages move
horizontally (traveling) or vertically (scrolling) to replace the first
message with the second. Off-time, on the other hand, is a message
change operation that involves the straightforward turning off of the first
message, with a period of blank screen, before the second message is
instantly 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 approachto the bridge may
be used to convey the message, “Fogahead…on
bridge…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
16. approachas 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 a
measure of average glance duration, 0.3 second, beused here as a
maximum permissible message change time limit.” The report further
advocates minimizing off-time between messages, where static message
changes are used, stating that “[a]s this interval of off-time is
lengthened, the difficulty of maintaining the continuity of attention and
comprehension is increased.”
The conservative nature of the authors’ position is reflected bothin the
report, and in over twenty years of practice since the report was issued.
The report cites studies indicating that, in some situations, the use of
electronic operations had a beneficial effect on traffic safety, by creating
a more visually-stimulating environment along an otherwise mindnumbing
segment 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 signs
nationwide utilizing the various operational capabilities for message
change, there has been no significant degradation to highway safety
reported. Many electronic signs used by highway departments now use
a mode of transition between messages or message segments, such as
traveling or scrolling. Drivers are apparently capable of attaching
primacy to the visual information most critical to the driving task, with
sign messages taking a secondary role.
The report further expresses its limited focus upon interstate and federal
aid primary highways. Noting the stimulating visual environment
created by full-animation signage in places like Times Square, Las
Vegas and Toronto’s Eaton Centre, the authors of the report agreed that
such signs added vitality and dimension to the urban core, but
discouraged the use of animation alongside the highway. The report
did not deal with the use of such signs, or their operational
characteristics, on roadways between the extremes of the interstate
highway and the urban core. In addition, animation has now been
used on highway-oriented signs in many locations for years, with no
reported adverse effect of traffic safety.
In sum, the report acknowledged the appropriateness of full-animation
electronic signs within the urban core, but recommended that full-animation
not be used along interstate and primary highways. It took a conservative
position on operations of such signs along highways, advocating static
message change sequences only, with no more than 0.3 seconds of message
change interval or “off-time” between messages. The message changes on
sequential segmented messages should be displayed such that a motorist can
see and read the entire chain of message segments in a single pass.
17. Messages should be permitted to change at “reasonable intervals.” Such signs
should 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 traffic
safety 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 sign
displays, no credible studies have established a correlation between EMDs and
a degradation in traffic safety.
An article in the Journal of Public Policy and Marketing in Spring, 1997,
arrived at the same conclusion. ProfessorTaylor, of Villanova University,
analyzing this lack of data to supportsucha 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 experience
that 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 is
desirable, full-animation EMDs have been shown to be viable without
degrading traffic safety.
• In an urban setting, such as along arterial streets, EMDs have been used
with static messages changed by use of transitions such as traveling,
scrolling, fading and dissolving, without any apparent impact on traffic
safety. Quite likely, this can be attributed to the primacy of the navigation
task, and the secondarynature of roadside signage.
• Along interstate and other limited access highways, the only significant
traffic safety analysis recommends the use of static messages only, and the
federal government permits message changes at “reasonable intervals.”
Many highway departments change messages on their own signs every 1-2
seconds. Thereport further recommends that sequential messages be
timed to ensure that the entire sequence of messages be displayed in the
time it takes a car to travel from initial legibility to beyond the sign. In
practice, and in the 20+ years since publication of this report, the
operational characteristics of such signs have been expanded to include
fading, dissolving, scrolling and traveling, without any apparent adverse
effect on traffic safety.
Regulationof Electronic Signs Board
The history of the regulation of electronic signs has been largely marked by
polar
18. extremes in regulation. A number of zoning and sign codes have treated such
signs as any other sign, with no special regulations. Others have attempted to
prohibit their use in the entirety, largely out of concerns for traffic safety, and in
some cases in the stated interest of aesthetics.
For the reasons stated above, the traffic safety concerns have been largely
unfounded. In decades of use and intense scrutiny, no definitive relationship
between 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 supportthe 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 in
the past motivated some communities to attempt to prohibit electronic signs
altogether. 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 be
displayed 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 costof 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 animation
after 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 becausethe 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 codetechnique 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
19. 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 codeviolation on a daily basis.
Other terminology may be used in sign codes, but the fact is that a regulation
must 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 changein message, and frame effects that accompany the message
display.
Many of these transition operations and frame effects are quite subtle, or
otherwise acceptable from a community standpoint. It is now possibleto define
these operations, in the codeitself, 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 message
signs are: 1) Duration of message display, 2) Message transition, and 3) Frame
effects. 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 ontheir 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 adoptlonger 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 a
sign codestandpoint. It is during the message transition or frame effect that the
eye 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 similar
subtle transitions and frame effects that do not have the
appearanceof moving text or images.
Level 3 Static Display with “Travel” or “Scrolling” transitions, or
20. similar transitions and frame effects that have text or
animated imagesthatappearto move or changein size, or be
revealed sequentially rather than all at once
Level 4 Full Animation, Flashing and Video
There are, in fact, other operations recognized within the industry. However, in
practice 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.
Forexample, communities like Las Vegas acceptfull animation as a
community standard, whereas others acceptfull 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 is
Procedural. Some signs may be acceptable always, while the community may
Determine that others are acceptable only in certain given circumstances.
Alternatives to be considered for a sign codeare 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 above
For 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 in
certain 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,
21. 4) Fully-animated/video displays in the downtown commercial district only,
subject to approval of a special use permit. The level of procedureinvolved
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 codelanguage that can be
used, for reference, to incorporate into a community’s sign code. The model
language suggests codescenarios based on each of the four levels of display
transitions. It also provides alternative language, for some scenarios, to either
incorporate a special review procedureor not. Of course, the model language
must be tailored to a particular community’s sign code. Variation may be
necessary, where, for instance, the special review procedure would be by the
local planning commission, city council or design review board. With ease, the
model codelanguage 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 use
permit] [in the zoning districts] subject to the following requirements:
a. OperationalLimitations. Such displays shall contain static messages
only, and shall not have movement, or the appearance or optical
illusion of movement, of any part of the sign structure, design, or
pictorial segment of the sign, including the movement or appearance of
movement of any illumination or the flashing, scintillating or varying of
light intensity.
b. Minimum DisplayTime. Each message on the sign must be displayed
for a minimum of (insert reasonable interval) seconds.
c. Message ChangeSequence. [Alternative 1: The change of messages
must be accomplished immediately.] [Alternative 2: A minimum of 0.3
seconds oftime with no message displayed shall be provided between
each message displayed on the sign.]
Model Electronic Sign CodeProvisions
Level 2-Static Display (Fade/Dissolve Transitions)
DISSOLVE – a mode of message transition on an Electronic Message Display
accomplished by varying the light intensity or pattern, where the first message
22. 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 Display
accomplished by varying the light intensity, where the first message gradually
reduces intensity to the point of not being legible and the subsequent message
gradually 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. Forsimplicity, 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
23. 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
24. 1. Transformation
2. Rectification
3. Filtration
4. 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.
TRANSFORMER RECTIFIER FILTER REGULATOR
25. 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 Rectification
A 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.
FILTER
Filters 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 Regulator
A 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
26. Circuit symbolof 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%.
PowerIndicator
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 by
Vdc = Vac √2
= 12* √2
Vdc = 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 CONTROLUNIT
The controlunit is made up of a single micro controller chip that can execute a
user program, normally for the purposeof controlling the device; the transistors
serve as switches and the line decoders.
27. 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 (ReadOnly 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.
28. 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 amplifier
XTAL2: 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 voltage
VSS: 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 codeat 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 decoderhas 2n output lines. Therefore, if it receives n inputs
(usually grouped as a binary or Boolean number) it activates one and only one
29. of its 2n outputs based on that input with all other outputs deactivated. A
decoder’s outputcodenormally has more bits than its input codeand practical
binary decodercircuits include 2-to-4, 3-to-8 and 4-to-16 line configurations.
A binary decoderconverts 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 decoderalong 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 decoderconverts 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 decoderalong 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 codepresent at the input, in other words it "de-codes"the
30. binary input and these types of binary decoders are commonly used as Address
Decoders in microprocessormemory 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 decoderis identical
to that of the basic demultiplexer. Therefore, we say that a demultiplexer is a
decoderwith an additional data line that is used to enable the decoder. An
alternative way of looking at the decodercircuit 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 codepresent 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 microprocessormemory 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 decoderis identical
to that of the basic demultiplexer. Therefore, we say that a demultiplexer is a
decoderwith an additional data line that is used to enable the decoder. An
alternative way of looking at the decodercircuit is to regard inputs A, B and C
31. 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 decodernetworks as shown.
Here a much larger 4-to-16 line binary decoderhas been implemented using two
smaller 3-to-8 decoders.
4-to-16 Binary DecoderConfiguration
Inputs A, B, C are used to select which output on either decoderwill 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" producedbya computing
device. In modern microprocessorsystems 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
32. 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 correctmemory device for a particular address and when
we specify a particular memory address, the correspondingmemory 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
decoderit activated and get start working. When a port1 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 decoderis a high performance memory decoding or data-routing
IC that requires a very short propagation delay times. The 74138 decodes oneof
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
33. Use of fonts.exe
This 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 code00h 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.
34. 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
35. 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 sucha 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
36. 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
RESISTORS
A resistor is a two terminal electronic componentthat produces a voltage across
its terminals that is proportional to the electric current passing through it in
accordanceto ohms law.
TRANSISTOR
37. This is a semi – conductordevice 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 DECODERS
Decoders 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-CONTROLLER
This is a single programmable chip that is designed to controlcircuits that are
interfaced with it. They usually consistof 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 canbe thin films, foils or
38. 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 Program
In 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 codewhere utmost speed,
small codesize, and hardware control are critical. The macro facility speeds
development and conserves maintenance time, becausecommon sequences need
be developed only once. The assembler supports symbolic access to all features
39. of the 8051 and is configurable for each 8051 derivative. The A51 assembler
translates an assembler sourcefile into a relocatable object module. If the
DEBUG control is used, or if the “Includedebugginginformation” optionis
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
sourcefiles and discusses the assembler controls that you may specify on the
command line and within the sourcefile. Using the controls described in this
chapter, you can specify which operations are performed by A51. Forexample,
you may direct the A51 assembler to: generate a listing file, producecross
reference information, and control the amount of information included in the
object file. You may also conditionally assemble sections of codeusing 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
40. 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 INTEGRATION
Usually 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 smoothprotocolor receiving and processing of
the information.
TEST PLAN
To 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 TESTING
1. 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 DECODERS
It operates on a principle of causing the output that correspondsto the
binary input to go LOW. At each binary input, the output pins respond
41. only if the enable pins are activated. The line decoderhas a tristate
capability. Therefore its operation is dependent on the activation pins and
the supply of the binary codes at the input pins.
3. PROCESSINGUNIT TEST
This 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 CONTROLSYSTEM TESTING
The controlis 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 PRECAUTION
It 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 system
3. 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. Forservices, 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
42. In the courseof 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
accommodatecertain 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
43. our economy such as banks, airports, restaurants, superstores, institutions,
entertainment, stockexchange 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 suchas
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.
.
References
1. A technical reference detailing the LED display array, RF interface and
scanning circuit was included as part of the 1978 29th ISEF exhibition in
Anaheim, CA.
2. B. Bahadur, Liquid Crystals: Applications and Uses. London: World
Scientific, 1990
44. 3. Co ship. (n.d.) LED Basic Information. [Online]. Available:
www.coshipled.com/english/downloads/basic%20concepts.pdfAugust 8,
2008 [date accessed]
4. C. Kuhnel, BASCOM Programming of Microcontrollers with Ease.
Berlin: Universal-Publishers, 2001.
5. EKTA’s Ukrainianproduced 3DLed TV makes The Guinness Book of
World Records, www.ekta-led.com
6. FoconEngineering. (n.d.) LED Colour Display Matrix Controller.
[Online]. Available: www.fuse-
network.com/fuse/demonstration/34_35/22918/FL_22918.pdf August 8,
2008 [date accessed]
7. International, Macmillan Press Ltd., London 1 978 , Vol. 26, pp 755-56 .
8. "Leyard Signs Technology LicenseAgreement with Dimencoto Launch
No-Glasses 3DLED Wall". News. Dimenco.
9. Mill man J, Halkias, C.C, Integrated Electronics , McGraw HillInternational
1972 , p 24, 27.
10.Mitchell's modular LED x-y (horizontally and vertically digitally scanned
array system) was cited in the 29th InternationalScienceand
EngineeringExposition "book of abstracts", p. 97, published by the
"ScienceService", Washington D.C. May 1978.
11.National Research Council (U.S.). Panel on Impact of Video Viewing on
Vision of Workers, Video Displays, Work and Vision. Washington:
National Academies Press, 1983. The Decoder. (n.d.). [Online]. Available:
http://www.electronics-tutorials.ws/combination/comb_5.html September
2, 2008 [date accessed]
12.R.K. Jurgen, AutomotiveElectronics Handbook. NewYork: McGraw-Hill
Professional, 19 Steven F. Barrett and Daniel J. Pack, Atmel AVR
Microcontroller Primer: Programming and Interfacing. London: Morgan
& Claypool Publishers, 2007The prototypeand scientific paper "Light
Emitting Diode Television Screen" were part of exhibit #635.
13.. Simpson, A, Testing Methods and Reliability Electronics , English
