- 1. Submitted By: Swarnim Maurya Bharat Bhagtani Vishu Jain (DR.
K.N. Modi Institute of Engg. & Tech. , Modinagar,
Ghaziabad)
2. CONTENTS 1. Project Idea 2. Introduction 3. Working Principle
4. Flow Chart 5. Schematic Diagram 6. Components used a) AT89S52
b)GSM Modem c)MX232 and DB9 Connector d)DECODER ICs i- IC 74154 ii-
IC74138 e)EEPROM (IC 24C02) 7- LED MATRIX 8- APPLICATION 9-
CONCLUSION 10- REFERENCES 3. PROJECT IDEA: Notice Board is primary
thing in any institution or organization or public utility places
like bus stations, railway stations and parks. But sticking various
notices day-to-day is a difficult process. A separate person is
required to take care of this notices display. This project deals
about an advanced hi-tech wireless notice board. The project is
built around a micro controller which provides all the
functionality of the display and wireless control. Display is
obtained on LED The advantage of this project being low cost and
low power consumption. 4. INTRODUCTION It presents an SMS based
notice board incorporating the widely used GSM to facilitate the
communication of displaying message on notice board via users
mobile phone. SIM300 GSM modem with a SIM card is interfaced to the
ports of the microcontroller with the help of AT commands. SIM300
is duly interfaced through a level shifter IC MAX32 to the
microcontroller. The messaged is thus fetched into the
microcontroller. It is further displayed on an electronic notice
board which equipped with LED display interfaced to microprocessor
powered by a regulated power supply from mains supply of 230 volts
ac. 5. WORKING PRINCIPLE The GSM Modem is first properly
initialized and then it checks for modem connectivity. The program
is written in microcontroller to perform this task. After that user
has to send SMS to GSM modem and message contents are finally
displayed on the LED matrix. The microcontroller used in this
project is Atmel 89S52. The data is sent to microcontroller through
MAX232 interface. MAX232 acts as logic level shifter IC. It means,
it converts TTL Logic Level to RS-232 and vise versa. 6. FLOW CHART
7. Schematic Diagram 8. COMPONENTS HARDWARE USED IC 74138 AS A 3 TO
8 LINE DECODER IC 74154 AS A 4 TO 16 LINE DECODER L.E.DS TOTAL 32
LINES IN 7 ROWS TOTAL 224 L.E.DS 1 M OHM PRESET STEP DOWN
TRANSFORMER 6 VOLT AC TWO DIODE AS A RECTIFIERIN 4007 ELECTROLYTIC
CAPACITOR 470 uF, 100 uF, 10uF CRYSTAL 3.58 Mhz 22pF CERAMIC
CAPACITOR WITH CRYSTAL 7805 REGULATOR 89S52 MICROCONTROLLER 558 PNP
TRANSISTOR 32 FOR COLOUM LINES, 7 FOR DATA LINE SOFTWARE USED Keil
u Vision Flash Magic 9. 89S52 Microcontroller Microcontroller is a
small computer on a single integrated circuit containing a
processor core, memory and programmable I/O peripherals. The 89S52
microcontroller has Harvard architecture with RISC (Reduced
Instruction Set Computer) concept. The 89S52RB2/RC2/RD2 device
contains a non- volatile 16kB/32kB/64kB Flash program memory that
is both parallel programmable and serial In- System and
In-Application Programmable. 89S52 has 8-bit ALU which can perform
all the 8- bit arithmetic and logical operations in one machine
cycle. The ALU is associated with two registers A & B special
function registers. 10. FEATURES 4 KB on chip program memory (ROM
or EPROM)). 128 bytes on chip data memory (RAM). 8-bit data bus
16-bit address bus 32 general purpose registers each of 8 bits Two
-16 bit timers T0 and T1 Five Interrupts (3 internal and 2
external). Four Parallel ports each of 8- bits (PORT0, PORT1,
PORT2, PORT3) with a total of 32 I/O lines. One 16-bit program
counter and One 16-bit DPTR ( data pointer) One 8-bit stack pointer
One Microsecond instruction cycle with 12 MHz Crystal. One full
duplex serial communication port. 11. MICROCONTROLLER AT89S52 PIN
DIAGRAM 12. BLOCK DIAGRAM schematic architecture CPU On-chip RAM
On-chip ROM for program code 4 I/O Ports Timer 0 Serial PortOSC
Interrupt Control External interrupts Timer 1 Timer/Counter Bus
Control TxD RxDP0 P1 P2 P3 13. GSM MODEM A GSM modem is a wireless
modem that works with a GSM wireless network. It operates at either
the 900MHz or 1800MHz frequency band. It supports voice calls and
data transfer speeds of up to 9.6kbits/s, together with the
transmission of SMS (Short Message Service). The GSM Modem comes
with a serial interface which the modem can be controlled using AT
command interface. 14. GSM SPECIFICATIONS Frequency Used : 890 to
960 Mhz Uplink Frequency : 890 to 915 Mhz Downlink Frequency: 935
to 960 Mhz Channel Bandwidth: 200 Mhz No. Of Channels: 124
Modulation Used GMSK Mobile Station Power Output: 0.8w,2.5w,8w
FDM-TDMA Technology is used in GSM. 15. AT COMMANDS 16. MAX 232 17.
MAX 232 IC MAX 232 that converts signals from an RS-232 serial port
to signals suitable for use in TTL compatible digital logic
circuits. The MAX 232 is a dual driver/receiver and typically
converts the RX, TX CTS and RTS signals. It changes a TTL Logic 0
to between +3 and +15 V, and changes TTL logic 1 to between -3 to
-15V, and vice versa for converting from RS232 to TTL. 18. DB9
Connector The DB9 connector is an analog 9-pin plug of the D- Sub
miniature connector family (D-Sub or Sub-D). The DB9 connector is
mainly used for serial connections, allowing for the asynchronous
transmission of data as provided for standard RS-232 (RS-232C). 19.
External Memory-24c02 It is a non-volatile memory and is used for
the storage of message in case any new SMS is not received by the
modem. It used as memory reservoir to store previous message. Pins
in 24C02- 1-SDA(Serial Data) 2-SCL(Serial Clock) 3-WP(Write
Protect) 4-Device/Page Address pins(AO,A1,A2) 5-Ground(GND) 6-VCC
20. Power Supply In this project firstly we use one step down
transformer. Step down transformer step down the voltage from 220
volt Ac to 12 volt Ac. This AC voltage is further converted into DC
with the help of rectifier circuit. In rectifier circuit we use TWO
diode. All the diodes are arranges as a bridge rectifier circuit.
Output of this rectifier is pulsating Dc. To convert this pulsating
DC into smooth dc we use one capacitor as a filter components.
Capacitor converts the pulsating Dc into smooth DC with the help of
its charging and discharging effect. Output of the rectifier is now
regulated with the help of IC regulator circuit . We use 7805
regulator then its means its is 5 volt regulator and if we use 7808
regulator then its means that it is 8 volt regulator circuit. In
this project we use 5 volt dc regulated power supply for the
complete circuit. Separate 9 volt dc power supply is used for the
relay coil 21. Schematic View of Power Supply Design Transfor mer
Diode for Rectification Capacitor LED Voltage Regulator IC 22. IC
74154 (4-16 line demultiplexer): Each or these 4-line-to-16-line
decoders utilizes TTL circuitry to decode four binary-coded inputs
into one of sixteen mutually exclusive outputs when both the strobe
inputs, G1 and G2, are low. The demultiplexing function is
performed by using the 4 input lines to address the output line,
passing data from one of the strobe inputs with the other strobe
input low. When either strobe input is high, all outputs are high.
These demultiplexers are ideally suited for implementing
high-performance memory decoders. All inputs are buffered and input
clamping diodes are provided to minimize transmission-line effects
and thereby simplify system design. 23. IC 74154 Connection
Diagram: 24. IC 74138 The DM74LS138 decodes one-of-eight lines,
based upon the conditions at the three binary select inputs and the
three enable inputs. Two active-low and one active-high enable
inputs reduce the need for external gates or inverters when
expanding. An enable input can be used as a data input for
demultiplexing applications. The DM74LS139 comprises two separate
two-line-to-fourline decoders in a single package. The active-low
enable input can be used as a data line in demultiplexing
applications. 25. Features Designed specifically for high speed:
Memory decoders Data transmission systems n DM74LS138 3-to-8-line
decoders incorporates 3 enable inputs to simplify cascading and/or
data reception n DM74LS139 contains two fully independent
2-to-4-line decoders/demultiplex DM74LS138 21 ns n Typical power
dissipation DM74LS138 -32 mW power 26. Schematic Diagram of IC74138
27. HOW LED MESSAGE IS DISPLAYED Message M will have the code - db
080h,0dfh,0e7h,0dfh,080h,0ffh HERE db means data is known as define
bit 28. APPLICATIONS The Campus Display System is aimed at the
colleges and universities for displaying day-to-day information
continuously or at regular intervals during working hours. Display
devices can be setup at various places in the campus. Being
GSM-based system, it offers flexibility to display flash news or
announcements faster than a programmable system. GSM-based campus
display system can also be used at other public places like
schools, hospitals, railway stations, gardens etc. without
affecting the surrounding environment. 29. CONCLUSION The display
boards are one of the major communications medium for mass media.
Local language can be added as a variation in this project. This
can be achieved by using graphics and other decoding techniques.
Also we realize that this project saves time, energy and hence
environment. Cost of printing and photocopying is also reduced as
information can be given to a large number of people from our
fingertips. Thus we can conclude that this project is just a start,
an idea to make use of GSM in communications to a next level. 30.
References The 8051 Microcontroller and Embedded Systems by
Muhammad Ali Mazidi and Janice Gillispie Mazidi, Pearson Education.
ATMEL 89S52 Data sheets www.fadooengineers.com www.wikipedia.org
31. Thank You!!!
