DESIGN AND IMPLEMENTATION OF SMS BASED NOTICE BOARD USING 8 BIT MICRO CONTROLLERS PDF Print E-mail
 

INTRODUCTION

The proposed system is based on ATMEL 89S52 µcontroller .

For doing this project we use some of the software like

  • Embedded C for programming the application software to the microcontroller.
  •  Protel schematic software is used for designing the circuit diagram for this project.
  •  Express PCB software is used for designing the PCB for this project.


(Since PCB making is a big process and involves lot of machineries which are expensive, we are going to outsource this to the manufacturer.)

ABSTRACT

Now a days every advertisement is going to be digital. The big shops and shopping centers are using the digital moving displays now. In Railway station and bus stands everything that is ticket information, platform number etc is displaying in digital moving display. But in these displays if they wants to change the message or style they have to go there and connect the display to PC or laptop.

 

Suppose the same message if the person wants to display in main centers of the cities means he have to go there with laptop and change the message by connecting into PC.This project we can use mainly for police or army .I.e. displays will be connected to all the main centers in city if they wants to display messages about something crucial within 5 minute, they can’t

 

 

So keeping in this mind we are designing a new display system which can access remotely, we are using the GSM technology to access the display’s is one of the new technology in the embedded field to make the communication between microcontroller and mobile.

 This project is a remote notice board with MODEM connected to it, so if the user wants to display some messages, he will send the messages in SMS format the MODEM in the display system will receive the message and update the display according to the message. For every message received from the user mobile, the system will check for the password and if the password is correct the controller will display the message. the LED s on the digital display board uses the latest hi-bread LCD modules (hi-bright), where LEDs are mounted on a rectangle plastic like enclosure and then wired as the 8/5 led matrix with 5 column and 8 rows. These LED’s have more brightness compared to the other LED now available in the market.

COMPONENTS USED

Power Supply 5v DC           -           7805

Microcontroller                   -           P89C51RD2      Phillips

Crystal                              -           11.0592 MHz

Shift register                      -           74HCT164

Memory                             -           Atmel 64k EEPROM                                          

MAX 232                            -           For Serial Communication

Buzzer                               -           Freq-1 to 18khz.Volt-5v-12vDC

GSM Transmitter and Receiver

5*8 led matrix display


  Embedded C.

WORKING PRINCIPLE

 

 

This is a very good project for college, police etc. This project has a moving message display, which can be used as the digital notice board, and also a GSM modem, which is the latest technology used for communication between the mobile and the embedded devices.

  System will work like when the user wants to display or update the notice board, he have to sent the message in his mobile defining the messages and then the password of the system to the number of the sim which is inserted in the display system MODEM. Then the MODEM connected to the display system will receive the SMS, the microcontroller inside the system is programmed in such a way that when the modem receives any message the microcontroller will read the message form serial port and verify for the password, if the pass word is correct then it will start displaying the messages in the display system.

The messages are displayed on the system using high speed techniques, the entire display column is connected to shift register output so that the characters are first shifting to each column and then the microcontroller will switch on the row one by one with small delay. This process is continuing in high speed so that the viewer will feel the display in a more brightness.


BLOCK DIAGRAM


 

 

 

COMPONENTS DETAILS

 

Power supply

The microcontroller and other devices get power supply from AC to Dc adapter through 7805, 5 volts regulator. The adapter output voltage will be 12V DC non regulated. The 7805/7812 voltage regulators are used to convert 12 V to 5V/12V DC.

Vital role of power supply in ‘Remote notice board using GSM with SMS

The adapter output voltage will be 12V DC non regulated. The 7805/7812 voltage regulators are used to convert 12 V to 5V/12V DC.


Micro controller-P89C51RD2

8051 based CMOS controller with Dual DPTR,

 32 I/O Lines,

WDT, PCA, 3 Timers/Counters,

 7 Interrupts/4 Priority Levels,

64K Bytes ISP FLASH EPROM

, 256 Bytes on-chip RAM,

768 Bytes on-chip XRAM


 

 

Vital role of micro controller in ‘Remote notice board using GSM with SMS

The micro controller inside the system is programmed in such a way that when the modem receives any message the micro controller will read the message form serial port and verify for the password, if the pass word is correct then it will start displaying the messages in the display system

 

 

The microcontroller is used to display the display system with LED connected as rows and columns using high speed scanning technique.

LCD is connected to microcontroller as 4 bit data mode, before displaying anything in LCD Initialization have to do ,so microcontroller will  control the LCD initialization  and select the data register and command register according to the purpose.

       Memory is connected to microcontroller using two pins, it is communicating with the microcontroller through I2C communication.

Buzzer is controlled by the microcontroller using single pins, Ie giving high means device will switch on and vice versa. Sometimes it may be interchange according to the transistor used to drive the device.

Buzzer

The buzzer subsystem produces a 2 KHz audible tone when powered. The buzzer will sound when the signal coming into the driver is high. It must be connected to a transistor, Darlington or transducer driver subsystem.

The buzzer is connected between the supply rail (+ V) and the input signal. This acts as load on the driver. When the input signal coming into the buzzer subsystem is low, a potential difference across the buzzer causes current to flow. It is this flow of current that causes the buzzer to sound.

Vital role of Buzzer in ‘Remote notice board using GSM with SMS

Buzzer is connected to microcontroller port pin, so microcontroller will give high or low to switch on/off buzzer. In this project it is used to define the normal/abnormal/active/deactivate condition of system/peripherals in sound form.

RS 232 CONVERTER (MAX 232N
)

This is the device, which is used to convert TTL/RS232 vice versa.

RS-232Protocol

RS-232 was created for one purpose, to interface between Data Terminal Equipment (DTE) and Data Communications Equipment (DCE) employing serial binary data interchange. So as stated the DTE is the terminal or computer and the DCE is the modem or other communications device.

RS-232 pin-outs for IBM compatible computers are shown below.  There are two configurations that are typically used: one for a 9-pin connector and the other for a 25-pin connector.

                       

Voltage range

The standard voltage range on RS-232 pins is _15V to +15V. This voltage range applies to all RS-232 signal pins. The total voltage swing during signal transmission can be as large as 30V. In many cases, RS-232 ports will operate with voltages as low as _5V to +5V. This wide range of voltages allows for better compatibility between different types of equipment and allows greater noise margin to avoid interference.
Because the voltage swing on RS-232 lines is so large, the RS-232 signal lines generate a significant amount of electrical noise. It is important that this signal does not run close to high impedance microphone lines or audio lines in a system. In cases where you must run these types of signals nearby one another, it is important to make sure that all audio wires are properly shielded.

The main role of the RS232 chip is to convert the data coming for the 12-volt logic to 5 volt logic and from 5 volt logic to 12 volt logic

Vital role of RS232 Converter (Max 232n) in ‘Remote notice board using GSM with SMS’

RS 232 CONVERTER is a chip to convert the TTL voltage levels into RS 232 level and vice versa, this chip is developed by Maxim Corporation.

            In this project GSM modem is communicated with the microcontroller using RS 232 serial data format Therefore to make compatible MODEM serial port with microcontroller serial port we are using the RS 232 converter.

      

External EEPROM memory (64 Kbytes)

These memory devices are used to store the data for off line process. The AT24C64 provides 65,536 bits of serial electrically erasable and programmable read only memory (EEPROM) organized as 8192 words of 8 bits each. The device is optimized for use in many industrial and commercial applications where low power and low voltage operation are essential. The AT24C64is available in space saving 8-pin PDIP.

 

Features

The 64K is

Internally organized as 256 pages of 32 bytes each.

2-Wire Serial Interface (I2C protocol)

High Reliability

– Endurance: 1 Million Write Cycles

– Data Retention: 100 Years

– ESD Protection: >3000V

 

Vital role of External memory in this project ‘Remote notice board using GSM with SMS’

    
EEPROM memory is electrically erasable programmable memory, it is communicating with the microcontroller using 12C communication.ie it contains one data pin and clock pin, these device is connected as slave to the microcontroller. The main application of memory in this project is to store the message coming form user mobile, the microcontroller is doing the operation of writing and reading to memory

GSM modem (900/1800 MHz)


Semens GSM/GPRS Smart Modem is a multi-functional, ready to use, rugged unit that can be embedded or plugged into any application. The Smart Modem can be controlled and customized to various levels by using the standard AT commands. The modem is fully type-approved, it can speed up the operational time with full range of Voice, Data, Fax and Short Messages (Point to Point and Cell Broadcast), the modem also supports GPRS (Class 2*) for spontaneous data transfer.

 

Description of the interfaces

The modem comprises several interfaces:

-          LED Function including operating Status

-          External antenna ( via SMA)

-          Serial and control link

-          Power Supply ( Via 2 pin Phoenix tm  contact )

-          SIM card holder

 

LED Status Indicator

The LED will indicate different status of the modem:

 

-          OFF                              Modem Switched off

-          ON                               Modem is connecting to the network

-          Flashing Slowly             Modem is in idle mode

-          Flashing rapidly             Modem is in transmission/communication (GSM only)

 

Vital role of GSM modem in REMOTE NOTICE BOARD USING GSM WITH SMS

GSM technology is one of the new technologies in the embedded field to make the communication between microcontroller and mobile. Now every embedded system is used to communicate with other system using GSM and GPRS technology, In this project MODEM is used to access the message sent by the user to display in notice board.

APPLICATION
  • colleges
  • school
  • hotels
  • railway stations
  • conference hall

FUTURE ENHANCEMENT

         Now we are displaying the messages in scrolling mode only, in future we can add so many designs so that user can send style command with message he wants to display the messages. We can add one more concept that user can sent 10 messages at a time with different styles.