ABSTRACT

LED matrix display has become an important symbol of the city lighting, modernization and information society with continuous improvement and beautification of people's living environment.

Notice board is primary thing in any institution/organization or public utility places like bus stations, railway stations and parks. But sticking various notice day-to-day is a very difficult process. A separate person is required to take care of this notice displays. This project deals about an advanced hi-tech notice board.

Matrix type displays is designed the AT89C52 Microcontroller from Atmel. This micro controller provides all the functionality of the displays and control. It is also take care of creating different displays effect of the given text.

Matrix type displays is designed using 5mm LED on a printed circuit board. A driver circuit is designed to drive all these LEDs . a simple pc can be connected to this system to enter the required text or notice. Several scrolling effects can be selected using functions of keyboard. The scrolling speed of the text also can be changed according to the user requirement.

After entering the text. The user can disconnect the pc. At any time the user can add or remove alter the text according to his requirement.

This project uses regulated 5V, 1A power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the AC output of secondary of 230/12V step-down transformer.INTRODUCTION Our aim is to build an automated wireless pantry order system using zigbee. We shall provide each bogie/compartment with a microcontroller based order placement unit. The unit shall have a keypad to browse through the menu. The menu items, their cost and information shall be displayed on the Smart Notice Board connected to microcontroller. User can navigate thorugh menu using keypad provided. The data for the menu can be written on an EEPROM connected to each such microcontroller based unit, so that portable data updation is possible (by changing only the EEPROM). Upon finalizing the order the user will be able to place it using keypad. The order placed shall be transmitted to the central server (PC) which will also have a zigbee module connected to it for data reception. Multiple such slave units can be installed; one in each compartment and so on.

Here is the project that I made on 34 pieces but here just for a sample I am driving it on 4 pieces of 8*8. I use 34 pieces of 7*5 sizes at that time. But basic idea behind it is same that is multiplexing.

For 34 pieces multiplexing ICs increases and if pieces are so big then for better brightness we can use NPN transistor array like ULN2803. Here for driving rows I use also pnp logic array UDN2981 that transfer power to row when controller logic is 1 and no power when logic is 0.

UDN2981 max supply input is 15 volt. so it can maximum transfer almost 14 to 15 volt to the rows but red leds enough bright on 5 volt . dot matrix pieces are also multicolor normally red and green in one package so for driving green leds logic is same as for reds but that need some high power as compare to red so raise the supply of UDN2981. UDN2981 can also be replaced by a 8 pnp transistor to use it as a switch.This project can be used as a digital notice board in university it has a pc interface so message can be updated to it and on power failure it remain in it because EEPROM is used in this project . EEPROM is AT 24C16 serial EEPROM having 2048 bytes.

BLOCK DIAGRAM

Transmitter

Receiver

Working The ZigBee module on PC is interfaced to computer using serial port via microcontroller.

A ZigBee module requires only three wires to interface with any serial device may it be a microcontroller or a PC. Those are Serial Transmit Tx, Serial Receive Rx, and Serial Ground (GND).

The remote module consists of a microcontroller based system with an 8X8 Dot matrix Display, EEPROM to save menu options and a ZigBee module to interface with central computer ZigBee module.

On PC side MAX232 is used in between microcontroller and PC to convert PC side voltage levels to microcontroller side and vice versa

METHODOLOGY ZigBee

ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4-2003 standard for wireless home area networks (WHANs), such as wireless light switches with lamps, electrical meters with in-home-displays, consumer electronics equipment via short-range radio. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.

Features: 3.3V @ 40mA

250kbps Max data rate

2mW output (+3dBm)

400ft (120m) range

Built-in antenna

Fully FCC certified

6 10-bit ADC input pins

8 digital IO pins

128-bit encryption

Local or over-air configuration

AT or API command set

Serial CommunicationSerial communication is a technique of transmitting data between two pieces of hardware. The smallest piece of data that is transmitted is the byte. A byte is made up of 8 bits. When data is transmitted between two pieces of hardware, the bits are sent one at a time. The hardware sends these bits by sending varying voltages across the wires connecting the devices. The sender and the receiver agree on how often a bit (or voltage level) will be sent.

How often a bit will be sent is referred to as baud rate or bits per second (bps). Then with the help of very precise clocks they can send a series of voltage levels between each other and then reassmble these voltage levels into bytes.

Zigbee Overview

ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost allows the technology to be widely deployed in wireless control and monitoring applications. Second, the low power-usage allows longer life with smaller batteries. Third, the mesh networking provides high reliability and more extensive range. The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, and low-power wirelessly networked monitoring and control products based on an open global standard. As per its main role, it standardizes the body that defines ZigBee, and also publishes application profiles that allow multiple OEM vendors to create interoperable products.Why ZigBee?

Reliable

Supports large number of nodes

Easy to deploy

Very long battery life

Secure

Low cost

Can be used globally

Microcontroller The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4 Kbytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmels high density nonvolatile memory technology and is compatible with the industry standard MCS-51 instruction set and pinout.

The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.Features

Compatible with MCS-51 Products

4 Kbytes of In-System Reprogrammable Flash Memory. Endurance 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-Level Program Memory Lock

128 x 8-Bit Internal RAM

32 Programmable I/O Lines

Two 16-Bit Timer/Counters

Six Interrupt Sources

Programmable Serial Channel

Low Power Idle and Power Down Modes

APPLICATIONS

Activity schedules

Internal communication

Promotion of events

Canteen menus

Health and Safety

Performance feedback

Community development

Room Scheduling

Evacuation procedures

Local instant messaging

Restaurants

Hotels,

Stadiums,

Cafes,

Where quick service establishments.

REFERENCE

http://electronics.howstuffworks.com/robot.htm http://www.seas.upenn.edu/~meam100/hando...botics.pdf http://engineering-ed.org/Robotics/documents http://www.site.uottawa.ca/~rabielmo/miniCourse