01-11-2012, 05:46 PM
GSM BASED NOTICE BOARD ON LCD DISPLAY
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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.
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.
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