Wireless Electronic Notice Board using GSM

Contents

• 1 Circuit Principle:
• 2 Circuit Diagram:
• 3 Circuit Components:
• 4 Software Requirements:
• 5 Circuit Design:
• 6 Circuit Algorithm:
• 7 Circuit Simulation Video:
• 8 How to Operate?
• 9 Project Output Video:
• 10 Circuit Advantages:
• 11 Circuit Applications:
• 12 Circuit Limitations:
• 13 Download Project Code
• 14 Related Articles
• We know the importance of notice boards in public places like railway stations, bus stations and airports. But changing notices day-to-day is a difficult task. This article explains you how to design a wireless electronic notice board  using GSM technology. The project displays the data on LCD whatever we sent from the mobile.

• Circuit Principle:

  When we send the message from the mobile, GSM modem which is arranged at the display unit receives the message. Now the controller reads the message from the GSM modem and displays in on LCD.
  When user sends the message from the mobile, GSM modem sends the below command serially to indicate that new message is received.
  +CMTI: “SM”,3
  In the above command number 3 indicates the location of the new message. Now you need to read this unread message to display on LCD. The command to read the message from GSM modem is
  at+cmgr=3
  Here the number 3 indicates the location of the message to be read. After giving this command GSM module send the below command serially.
  +CMGR: “REC UNREAD”,”MD-WAYSMS”,,”13/05/20,15:31:48+34″
  Electronics Hub
  In the above command “REC UNREAD” indicates that message is unread message, “MD-WAYSMS” indicates sender mobile number or name, 13/05/20 indicates the date, 15:31indicates time and Electronics hub is the content of the message.
  From the above command we need to extract message (Electronics Hub) sent by the user to display on notice board.

  Circuit Diagram:

• 
• 
  

  Circuit Components:

  • AT89C51 controller
  • AT89C51 Programming board
  • 16*2 LCD
  • MAX232 level converter
  • GSM sim 300 module
  • Programming cable
  • DC battery or 12V,1A adaptor
  • 5V power supply circuit
  • 0.1uF ceramic capacitors – 4
  • 33pF capacitors – 2
  • 10uF electrolytic capacitor
  • 12MHz crystal
  • 10k (1/4 watt) resistor
  •  Single pin connecting wires

  Software Requirements:

  • Keil compiler
  • Flash magic
  • Proteus

  Circuit Design:

  The above circuit consists of 8051 controller, GSM module, Level converter and 16*2 LCD. LCD is connected to P1.0 and it is used to display message. GSM module is connected to controller through the max232 IC. Here it is used for level conversion.

  Here LCD is used in 4 bit mode. Means only 4 data lines are required to display the data. These data lines are connected to P1.4, P1.5, P1.6 and P1.7 and control pins RS, RW, EN pins are connected to P1.0, P1.1 and P1.2 respectively.

  Here the controller logic levels and GSM module logic levels are different. Hence we use max232 level converter as a mediator between Controller and GSM to transfer the data. To know more details about max232 refer Max232 Datasheet

  In order to communicate with GSM we need to send some AT commands using serial communication (UART protocol). Here GSM sim 300 module is used. This module requires 9600 baud rate. To know more details about GSM go through the article GSM Interfacing with 8051 Microcontroller

  Circuit Algorithm:

  1. Initialize the LCD and UART protocol
  2. Check for the command +CMTI: “SM”,3 (Location number) to know weather the new message is received or not
  3. If you receive the command then store message location number.
  4. Now read that particular location and extract the body of the message
  5. Display the message on LCD

  Use below code to display message on LCD wirelessly using GSM.

  while (rx_data() ! = 0x0d);                     

  while (rx_data() ! = 0x0a);                      

  if (rx_data() == ‘+’)

  {

  if (rx_data() == ‘C’)

  {

  if (rx_data() == ‘M’)

  {

  if (rx_data() == ‘T’)

  {

  if(rx_data()==’I’)

  {

  while (rx_data() != ‘,’);

  a = rx_data ();

  delay_ms (10);

  tx_string (“at”);

  tx_data (0x0d);

  tx_data (0x0a);

  tx_string (“at + cmgf =1”);

  tx_data (0x0d);

  tx_data (0x0a);

  tx_string (“at + cmgr =”);

  tx_data (a);

  tx_data (0x0d);

  tx_data (0x0a);

  while (rx_data() ! = 0x0a);

  while (rx_data() != 0x0a);

  while (rx_data() ! = 0x0a);

  for (i=0; i<15; i++)

  {

  read [i]= rx_data();

  }

  lcd_stringxy(1,0,read);

  delay_ms (5000);

  }

  }

  }

  }

  }

• How to Operate?
1. Write the program to the wireless electronic  notice board using keil software
2. Now burn the program to the microcontroller with the help of flash magic.
3. Give the connections as per the circuit diagram.
4. Use power supply circuit to provide 5V DC to the microcontroller
5. Insert the SIM (Subscriber Identity Module) to the GSM module.
6.  Now switch on the supply
7. Send SMS to the GSM module using other mobile
8. Now you can see the same message on LCD.

• Circuit Advantages:

  • No need of any complex wires to display the message on LCD as it is wireless.
  • Consumes less power and easy to operate.
  • The circuit is portable.

  Circuit Applications:

  • Used in bus stations, railway stations, parks, etc. to display the messages wirelessly
  • This Project is used in colleges and organizations.
  • source:http://www.electronicshub.org