1. GSM BASED NOTICE BOARD
ON LCD DISPLAY

2. INTRODUCTION
• In this project we are using GSM Modem
to receive SMS from user mobile and
display the same message on LCD.
• GSM is interfaced with 89S52
Microcontroller through Max232
interface. It is connected to controller
logic board using serial cable.
• We are using 16*2 LCD Message Display.

3. 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 LCD.
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.

4. HARDWARE COMPONENTS
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7805 Regulator
89S52 MCU
MAX232 Interface
GSM Modem
Serial Cable
16*2 LCD Display

5. GSM SPECIFICATIONS :~
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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.

8. Power supply
The microcontroller operating voltage is +5V DC.
The following components are used to construct the power supply circuit.

9. Power Supply Description:
 230V AC supply is given to the step down transformer .
 The output of the step down transformer is given to bridge rectifier.
 The bridge rectifier is formed with diodes. The bridge rectifier converts the AC
voltage into DC voltage.
 But the output DC Voltage contains some AC component (ripples).
So we use capacitors as a filter for removing ripples.
 The output DC Voltage is given to the positive voltage regulator LM7805 .
So the output of the regulator will be the regulated +5V DC.
 To indicate the condition of the circuit we place LED at the end of the circuit.

10. The most commonly used Character based LCDs are based on Hitachi's
HD44780 controller .
Pin Description
The most commonly used LCDs available in the market today are single Line,
double Line or four Line LCDs and support at most of 80 characters.
Most LCDs with one controller has 14 Pins and LCDs with two controller has 16
Pins (two pins are extra in both for back-light LED connections).

11. LCD Pin Diagram

12. Pin description of 16*2 LCD is shown in the table below.

13. BLOCK DIAGRAM
GSM
MODEM
MAX232
INTERFACE
AT89S52
MCU
16*2 LCD
DISPLAY
REGULATED POWER SUPPLY

14. at89s52
Compatible with MCS ®51
products
8Kb of ISP flash memory
256x8 bit internal RAM
32 Programmable I/O
lines
Three
timer/counters
Full duplex UART serial
channel

15. Features of 89S52
• 8-bit CPU
• 64K Program Memory address space
• 64K Data Memory address space
• 8K bytes of on-chip Program Memory
• 256 bytes of on-chip Data RAM

16. Block Diagram
External interrupts
Interrupt
Control
On-chip
ROM for
program
code
Timer/Counter
On-chip
RAM
Timer 1
Timer 0
CPU
OSC
Bus
Control
4 I/O Ports
P0 P1 P2 P3
Address/Data
Serial
Port
TxD RxD
Counter
Inputs

17. Pin diagram of
at89s52

18. The simplest connection between a PC and microcontroller
requires a minimum of three pins, RxD (receiver, pin2), TxD
(transmitter, pin3) and ground (pin5) of the serial port of
computer.

19. SOFTWARE TOOLS
• Embedded C Code
• Keil Compiler
• ucFlash

20. Advantages & applications
• Low cost
• Flexible
• Low power consumption
APPLICATIONS:
• Can be used in industries
• Can be used in Nuclear plants
• Can be used in mines

21. reference
• “The 8051 Microcontroller and Embedded
Systems” by Muhammad Ali Mazidi and Janice
Gillispie Mazidi, Pearson Education.
• ATMEL 89S52 Data sheets