Gsm message display

GSM BASED NOTICE BOARD ON LCD DISPLAY

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.

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.

HARDWARE COMPONENTS

• 7805 Regulator • 89S52 MCU• MAX232 Interface• GSM Modem• Serial Cable• 16*2 LCD Display

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.

Power supplyThe microcontroller operating voltage is +5V DC.

The following components are used to construct the power supply circuit.

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.

Liquid Crystal Display

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).

LCD Pin Diagram

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

BLOCK DIAGRAM

AT89S52 MCU

MAX232 INTERFACE

REGULATED POWER SUPPLY

16*2 LCD DISPLAY

GSM MODEM

at89s52Compatible with MCS ®51 products8Kb of ISP flash memory256x8 bit internal RAM32 Programmable I/O linesThree timer/countersFull duplex UART serial channel

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

Block Diagram

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

Address/Data

Counter Inputs

Pin diagram of at89s52

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.

SOFTWARE TOOLS

• Embedded C Code

• Keil Compiler

• ucFlash

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

reference

• “The 8051 Microcontroller and Embedded Systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi, Pearson Education.

• ATMEL 89S52 Data sheets

THANK YOU