|DESIGN AND IMPLEMENTATION OF SMS BASED NOTICE BOARD USING 8 BIT MICRO CONTROLLERS|
For doing this project we use some of the software like
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.
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
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.
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.
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.
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.
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.
This is the device, which is used to convert TTL/RS232 vice versa.
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.
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.
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.
The 64K is
Internally organized as 256 pages of 32 bytes each.
2-Wire Serial Interface (I2C protocol)
– 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’
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.
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.