Multiuser SMS Based Wireless Electronic Notice Board
Abstract— This is the model for displaying notices in colleges 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. The hardware board contains microcontroller AT89c52 at the heart of the system. The microcontroller is interfaced with GSM Modem via MAX232 level convertor. It is used to convert RS232 voltage levels to TTL voltage levels and vice versa. The hardware also has a 64K EEPROM chip AT24C64. This EEPROM is used to store the timings and messages to be displayed. Hardware also contains a real time clock DS1307 to maintain track of time. A 16x2 Character LCD display is attached to microcontroller for display. Microcontroller coding will be done using Embedded C and Kiel. PC Coding will be done using Visual Basic. Multiple Users are authorized to update notices on the electronic notice board by providing them password. We can use a PC with an administrator for monitoring the system.
Keywords—Microcontroller 89c52, GSM Modem, MAX 232 level converter, Embedded C, Keil.
Wireless communication has announced its arrival on big stage and the world is going mobile. We want to control everything and without moving an inch. This remote control of appliances is possible through Embedded Systems. The use of “Embedded System in Communication” has given rise to many interesting applications that ensures comfort and safety to human life. In this paper, it is proposed to design a model where the message to be displayed is sent through a SMS from an authorized transmitter. The toolkit receives the SMS, validates the user and displays the desired information after necessary code conversion. The main components of the toolkit contains microcontroller 89c52 which is interfaced with PC via MAX232 level convertor. MAX 232 level converter is used to convert RS232 voltage to TTL voltage levels and vice versa. We use PC's serial port to interface microcontroller. A 16x2 Character LCD display is attached in byte mode to port 1 of microcontroller. This display will be used to display the messages /advertisements. Microcontroller coding will be done using Embedded C and Kiel. PC Coding will be done using VB. Nokia PC Connectivity SDK is a tool used in VB for GSM modem interfacing. The modem transmits the stored message through the COM port. The microcontroller displays the message in the LCD display board.The microcontroller used in this case is AT89c52. MATRIX SIMADO GDT11 is used as a GSM modem. In the prototype model, LCD display is used for simulation purpose. While implementation this can be replaced by actual display boards.
II. Design Layout
The block diagram For Wireless GSM based electronic notice display is shown in figure 1.
Fig.1 Block Diagram of the System
The whole system is basically divided into two sections: Transmitting and Receiving. Transmitting section consists of just a mobile. Any type of user (sim number) can be used, as users are assigned password for accessing the system. Authorised users send the message that they want to display on the notice board to the receiving section’s mobile number and the message will be displayed only if the users have the authentication password. Receiving section on the other hand consists of a GSM modem to receive message. Received SMS is then extracted by PC with the help of a VB program using AT commands. SMS are then sent to microcontroller using MAX232 IC and PC’s serial port. Microcontroller finally displays it on LCD display.
III. Hardware description
Microcontroller is used for interfacing the LCD display with PC to display messages. The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable and erasable read only memory (PEROM). The device is compatible with the industry-standard 80C51 and 80C52...
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