MULTIUSER MULTIUSER GSMGSM BASED BASED

WIRELESS WIRELESS ELECTRONIC ELECTRONIC

NOTICE BOARD NOTICE BOARD

Submitted To:Submitted To:Mrs. Hareeta MalaniMrs. Hareeta MalaniAsst. ProfessorAsst. ProfessorICT, MLVTECICT, MLVTEC

INTRODUCTION

The main aim of the project will be to design a GSM based electronic notice display system which can replace the currently used programmable electronic display. It is designed for displaying notices in college on electronic notice board by sending messages in form of SMS through mobile, it is a wireless transmission system which has very less errors and maintenance.

DESIGN OVERVIEW

The design of the project is basically divided into:

1. Transmitting Section

2. Receiving Section

Transmitting Section consists of just mobile which has inbuilt GSM modem for wireless data transfer through GSM.

GSM (Global System for Mobile communications: originally from Group Special Mobile) is the most popular standard for mobile phones in the world.

GSM NETWORK

GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity.

The modulation used in GSM is Gaussian minimum-shift keying (GMSK), signal to be modulated onto the carrier is first smoothed with a Gaussian low pass filter prior to being fed to a frequency modulator which greatly reduces adjacent channel interference).

TRANSMITTING SECTION

Since it is a multiuser system, various users are authenticated to use the system or display messages on the notice board.

For security, individual passwords are provided to authorized users. To display their message on notice board, a user need to authenticate itself with the system by sending message containing the assigned password and the text to the receiver section’s SIM number.

The receiving section’s system verifies password and sends response to the user and displays the text on the electronic notice board.

BLOCK DIAGRAM

RECEIVING SECTION

THE MICROCONTROLLER

Microcontroller is the heart of the system. It is used for interfacing the display, memory and other peripherals with GSM modem.

The microcontroller used in this case is AT89c52. It is a low-power, high performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable and erasable read only memory. It is compatible with the industry-standard 80C51 and 80C52 instruction set and pin out.

GSM MOBILE

A GSM mobile is used in our project to receive messages at receiving section. GSM Mobile consists of GSM Modem. It is a wireless modem that works with a GSM wireless network. It sends and receives data through radio waves.

In our project, we are using China set NONY 326. which give compatible mobile devices wireless connectivity using the GSM 850/900/1800/1900 MHz cellular net-works.

It has dual sim and dual standby feature, alonwith this, it supports wireless bluetooth 2.0.

DISPLAY UNIT(LCD)

One of the most common devices attached to an 8051 is an LCD display. Here we have used 16x2 Hitachi HD44780 compatible module, having 16 pins including 2 pins for backlight.

MAX232

The MAX232 is a dual driver/receiver that includes a capacitive voltage generator to supply EIA-232 voltage levels from a single 5-V supply and converts EIA- 232 inputs to 5-V TTL/CMOS levels.

The microcontroller is interfaced with PC via MAX232 level convertor. It is used to convert RS232 voltage to TTL voltage levels and vice versa. We use PC's serial port to interface microcontroller.

In PC, at RS-232 voltage levels, logic 1 varies from -3 to -15 volts and logic 0 from +3 to +15 volts. The microcontroller which works on TTL logic levels, logic 1 is +5 volts and logic 0 is 0 volts. Therefore to interface the two we use a MAX 232 driver IC.

POWER SUPPLY

Power Supply is an important part of a circuit. It provides required supply to different blocks of the circuit from input 230 VAC.

RS-232 CABLE

RS -232 is used to connect PC to microcontroller. It is based on RS232 standard.

These can be classified as Data Terminal Equipment (DTE) or Data Communication Equipment (DCE); this defines at each device which wires will be sending and receiving each signal.

In general and according to the standard, terminals and computers have male connectors with DTE pin functions, and modems have female connectors with DCE pin functions.

RS232 CABLE

Other devices may have any combination of connector gender and pin definitions. At one end of the cable, a male DB9 connector is used and at another, a female DB9 connector is used. Both are of same pin out.

INTERFACING

Microcontroller-LCD Interfacing:

STEPS OF LCD INTERFACING

Make hardware connection

RS=P3.2 (sbit rs =P3^2)

RW=P3.3(sbit rw=P3^3)

EN=P3.4 (sbit en =P3^4)

P1.0-P1.7—DB0-DB7 (sbit begin=P0.0; sfr load data=0x90;)

LCD Initialization

Sending data to LCD

Display data

MICROCONTROLLER-PC INTERFACING

PC-MAX232 INTERFACING

PC is connected to MAX 232 level converter via RS232 cable.

Male part of RS232 cable is connected to PC and female part is connected to MAX 232 converter.

Pin2 of RS232 is receive data line and pin 3 is transmit data line. Pin 2 of RS232 is connected to pin no 13 R1IN of MAX 232 converter and pin 3 of RS232 is connected to pin no 14 T1OUT of MAX232 converter.

MAX232-MICROCONTROLLER

INTERFACING

MAX232-MICROCONTROLLER

INTERFACING

To provide interfacing between them , the MAX 232 level converter provides output in the form of TTL CMOS logic levels since PC operates on TTL CMOS logic levels.

The pin no 11 T1 IN of MAX232 is connected to pin no 10 P3.0 RXD of microcontroller and pin no 12 R1OUT OF MAX 232 is connected to pin no11 P3.1 TXD of microcontroller.

SOFTWARE DESCRIPTION

EXPRESS PCB:

Express PCB is free PCB software and is a snap to learn and use. With this, designing circuit boards is simple for the beginner and efficient for the professional.

There are two parts to Express PCB, CAD software and board manufacturing service.CAD software includes Express SCH for drawing schematics and Express PCB for designing circuit boards.

We begin by drawing a schematic using ExpressSCH.

Next, we use the ExpressPCB program to lay out our PC board. If link our schematic to ExpressPCB, it will guide us through the wiring process.

SNAPSHOTS OF EXPRESS PCB AND

EXPRESS SCH

FINAL CIRCUIT USING EXPRESSSCH

FINAL PCB LAYOUT USING EXPRESS PCB

Bottom Layer TOP Layer

EMBEDDED C:

Embedded C is language for programming microcontroller for embedded applications. There is a large - and growing – international demand for programmers with 'embedded' skills, and many desktop developers are starting to move into this important area.

The reasons for writing programs in C

It is easier and less time consuming to write in C than Assembly

C is easier to modify and update

We can use code available in function libraries

C code is portable to other microcontroller

SAMPLE PROGRAM IN EMBEDDED C

KEIL COMPILER:

Keil is basically compiler to compile embedded C programs. The Keil 8051 Development Tools are designed to solve the complex problems facing embedded software developers.

It is compiler for debugging an Embedded C Program. It creates hex file from the compiled C program which can be burned into IC

CREATING HEX FILE

Check the Create HEX File box under Options for Target — Output, and μ Vision will automatically create a HEX file during the build process.

Select the desired HEX format through the drop-down control to generate formatted HEX files, which are required on some Flash programming utilities.

VISUAL BASIC:

Visual Basic (VB) is an event driven programming language and associated development environment from Microsoft for its COM programming model. Visual Basic was derived from BASIC and enables the rapid application development (RAD) of graphical user interface (GUI) applications.

Visual Basic Interfaces Mobile-PC and PC-microcontroller and provides a graphical user interface to access and monitor the system. A user interface window is created.

FORM(USER INTERFACE WINDOW)

USER INTERFACE WINDOW

It is the main window which will be visible to administrator.

In the message assigned box, we have to assign SIM position of the message which will be extracted by the system.

In the port assigned box, we will type the port number which is assigned to us by PC when we connect Bluetooth to it.

Get message is selected when we have to start getting messages from mobile.

Send message is selected when we have to stop getting message and send message to user for conveying any kind of information

USER INTERFACE WINDOW

The two left windows are there to show password and message respectively.

The right window shows the AT command internal processing by the VB program

The password setting button in the middle will link us to password setting window as explained in the next section…..

PASSWORD SETTINGS

Since our project deals with multiple users, individual passwords are provided to each user.

In our project, we have authorized 3 users and a 3-letter length password is assigned to each one. Individually. If due to any reason, user wants to change its password, they can contact administrator at PC.

They can choose their password of their choice and their personal password would be changed.

WINDOW FOR PASSWORD SETTING

FUNCTIONAL FLOWCHART

FUTURE ENHANCEMENTS

Alphanumeric LCDs have a limitation on size as well as no of characters. These can be replaced with large LED display boards

Robots can be controlled in a similar fashion by sending the commands to the robots.

APPLICATIONS

Educational Institutions and Organizations

Crime Prevention

Managing Traffic

Advertisement

Railway Station

Than

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