Abstract :
LED-based
moving-message displays are becoming popular for transmitting information to large
groups of people quickly. These can be used indoors or outdoors. We can find
such displays in areas like railway platforms, banks, public offices, hotels,
training institutes, nightclubs and shops. Compared to LEDs, liquid-crystal displays
(LCDs) are easy to interface with a microcontroller for displaying information
as these have many built-in functions. But these can’t be observed from a distance
and large size LCDs are very costly. LED-based displays can be of two types:
dot-matrix and segmental. If you implement a moving-message display with
multiplexed dot-matrix LEDs, it will be very costly for displaying 16 characters
or more at a time.
Moreover, programming will require a lot of data memory or
program memory space. An external RAM may be needed to complement a
microcontroller like AT89C51. However, if you use alphanumeric (16-segment LED)
displays for the above purpose, programming burden is reduced and also it
becomes highly cost-effective. You can make your own display panel consisting
of 16 alphanumeric characters at a much lower cost. The circuit presented here
uses 16 common-anode, single-digit, alphanumeric displays to show 16 characters
at a time. Moreover, programming has been done to make the characters move in a
beautiful manner. A message appears on the panel from the right side, stays for
a few seconds when the first character reaches the leftmost place and then goes
out from the left side. It displays 16 different messages to depict different
occasions, which canbe selected by the user through a DIP switch.
BASIC
COMPONENTS :-
SEMICONDUCTORS:
IC1 - AT89S51
microcontroller
IC2, IC3 –
74HC138 3-to-8 decoder
IC4 - 7805
5V regulator
T1-T16 -
BC558 pnp transistor
D1-D4 -
1N4007 rectifier diode
DIS1-DIS16
- KLA51 common-anode
Alphanumeric
display
LED1 - 5mm
LED
RESISTORS
(ALL ¼-WATT, ±5% CARBON):
R1-R16 -
2.2-kilo-ohm
R17-R32 -
120-ohm
R33-R37 -
10-kilo-ohm
R38 -
220-ohm
CAPACITORS:
C1, C2 -
33pF ceramic disk
C3 -
2200μF, 25V electrolytic
C4 - 1μF,
16V electrolytic
C5 - 10μF,
16V electrolytic
C6 - 0.1μF
ceramic disk
MISCELLANEOUS:
X1 - 220V AC
primary to 9V,500mA secondary transformer
XTAL -
11.0592MHz crystal
S0-S3 -
4-pin DIP switch
S4 -
Push-to-‘on’ switch
PCB
Construction:-
PCB
construction isan actual-size, singleside PCB layout for the microcontroller-
based moving-message display circuit, except displays DIS1 through DIS16,
transistors T1 through T16 and resistors R17 through R32. Component layout for
this PCB is shown in figure. Figure shows the PCB for displays DIS1 through
DIS8, transistors T1 through T8 and resistors R17 through R24. Component layout
for this PCB is shown in another figure. You need to use an additional PCB as
shown in Fig for DIS9 through DIS16, so as to configure 16 alphanumeric displays.
For this PCB, the corresponding components will be transistors T9 through T16
and resistors R25 through R32 in addition to displays DIS9 through DIS16. Cor-
responding connector are provided to make a proper connection. Connectors CON2,
CON4 and CON6 of Fig. are connected to CON2, CON4 and CON6 of Fig.,
respectively, through external wires to interface DIS1 through DIS9. Connectors
CON3, CON5 and CON7 of Fig are connected to CON2, CON4 and CON6 of Fig. 5,
respectively, through external cable to interface DIS9 through DIS16.
Future
enhancements :-
Many more
messages would be possible if complete Port-3 is used for message selection.
Pins RxD, TxD, INT0 and INT1 have been kept free, so that these can be used for
interfacing with the serial port of the PC. Also, interrupt pins can be used to
display some message and sound an alarm in the case of an emergency. For
example, a fire sensor can be connected to ‘INT0’ and a vibration detector to
‘INT1.’ These pins can also be used to send signals to synchronise a similar
system that displays another related message at the same time, so a
16-character, twoline display is made possible.
APPLICATIONS:-
LED Moving Message
Signs are used in any appropriate locations.LED Moving Message Signs are used
in any appropriate locations to communicate different kind of messages, from
time to time, to many number of people who pass by such area.PowerOn
Automations Private Limited is a group company of M/s Manilec Controls and
Devices Private Limited company incorporated in early 90’s for manufacturing of
Electronic and Electrical products.
To display real
time and temperature: Large size digital clocks indoor or outdoor for shop
floors, towers, petrol pumps, educational institutes, etc. The moving display
functions grab attention of the people to whatever you want to say. Moving
message has a battern backed memory of 10000 character letters and is available
in various sizes to suit your requirement.
Bringing forth a
wide range of attractive and effective advertising solutions through LED
display systems, animation sign boards, lead token boards, lighting &
display signs, electronic signs, etc.
Download :
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