Wireless electronic notice board using zigbee free essay sample

Notice boards play a vital role mostly in educational institutions. The events, occasions or any news, which has to be passed to the students, will be written on the notice boards present in every floor in the colleges or schools. The present system is like, a person will be told the news and he has to update this news on all the notice boards present in the college or school. This will be seen mostly during the examination seasons. The time table or the schedule of the exams has to be given to the students. This will be done by writing the details on the notice boards. But this process consumes a lot time to update the news on all the notice boards and there may be chances that the person responsible may commit some mistakes or he may be absent sometimes. So, this may create disturbances and the entire schedule may be disturbed. To avoid all these, Wireless Notice Board have been designed which completely eliminates the manual work. Zigbee is PAN technology based on the IEEE 802. 15. 4 standard. Unlike Bluetooth or wireless USB devices, zigbee devices have the ability to form a mesh network between nodes. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area. The project is built around the AT89S52 microcontroller from Atmel. This microcontroller provides all the functionality of the display and wireless control. It also takes care of creating different display effects for given text. Alphanumerical keypad is interfaced to the transmitter to type the data and transmit. The message can be transmitted to multipoint receivers. After entering the text, the user can disconnect the keyboard. At anytime the user can add or remove or after 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 o/p of secondary of 230/12V step down transformer. 1. 2 Proposed model:- Our proposed model consists of two modules i. e. one transmitter and one or more receiver module. The transmitter module consists of interfacing computer via serial interface to the zig- bee module. The receiver module placed at the remote end consists of zigbee module interfacedwith a microcontroller for displaying messages on LCD. Password based authentication is employed on the transmitter side in order to provide access control to only authorized users. Primarily 162 LCD is been used for displaying messages which we can further extend to larger LCD. 1. 3 Block diagram for the proposed model:- 1. 4 HARDWARE AND SOFTWARE:- Hardware components required: AT89S52 based our own developed board Power supply Zigbee Max232 Lcd Pc Software required: Embedded ‘c’ RIDE to write code ISP to burn the chip CHAPTER-2 2. 1 INTRODUCTION TO EMBEDDED SYSTEMS: Embedded systems are designed to do some specific task, rather than be a general-purpose computer for multiple tasks. Some also have real time performance constraints that must be met, for reason such as safety and usability; others may have low or no performance requirements, allowing the system hardware to be simplified to reduce costs. An embedded system is a combination of hardware and software which is custom built for system specific purpose, as the requirements of each system vary considerably. Depending on the quantity and functionality needed, the embedded hardware is cost customized and software that goes into it also varies widely to meet desired functionality. 2. 1. 1 Variety of embedded systems: Embedded systems are commonly found in consumer, cooking, industrial, automotive, medical, commercial and military applications. Telecommunications systems employ numerous embedded systems from telephone switches For the network to cell phones at the end-user. Computer networking uses dedicated routers and network bridges to route data. Consumer electronics include personal digital assistants (PDAs), mp3 players, mobile phones, videogame consoles, digital cameras, DVD players, GPS receivers, and printers. Household appliances, such as microwave ovens, washing machines and dishwashers, include embedded systems to provide flexibility, efficiency and features. Advanced HVAC systems use networked thermostats to more accurately and efficiently control temperature that can change by time of day and season. Home automation uses wired- and wireless-networking that can be used to control lights, climate, security, audio/visual, surveillance, etc., all of which use embeddeddevices for sensing and controlling. Transportation systems from flight to automobiles increasingly use embedded systems. New airplanes contain advanced avionics such as inertial guidance systems and GPS receivers those also have considerable safety requirements. Various electric motors — brushless DC motors,induction motors and DC motors — use electric/electronic motor controllers. electric vehicles, and hybrid vehicles increasingly use embedded systems to maximize efficiency and reduce pollution. Other automotive safety systems include antilock breaking systems. Medical equipment uses embedded systems for vitalsigns monitoring, electronic stethoscopes for amplifying sounds, and various medical imaging (PET, SPECT, CT, MRI) for non-invasive internal inspections. Embedded systems within medical equipment are often powered by industrial computers. Embedded systems are used in transportation, fire safety, safety and security, medical applications and life critical systems, as these systems can be isolated from hacking and thus, be more reliable. For fire safety, the systems can be designed to have greater ability to handle higher temperatures and continue to operate. In dealing with security, the embedded systems can be Self-sufficient and be able to deal with cut electrical and communication systems. 2. 1. 2 Characteristics: Embedded systems are application specific single functioned. Embedded systems are not always standalone devices Efficiency is of paramount importance for embedded systems. They are optimized for energy, code size, execution time, weight dimensions, and cost. Embedded systems are typically designed to meet real time constraints; a real time system reacts to stimuli from the controlled object/ operator within the time interval dictated by the environment. For real time systems, right answers arriving too late (or even too early) are wrong. Embedded systems often interact (sense, manipulate communicate) with external world through sensors and actuators and hence are typically reactive systems; a reactive system is in continual interaction with the environment and executes at a pace determined by that environment. Many embedded systems consists of small, computerized parts with in a larger device that serves a more general purpose. The program instructions written for embedded systems are referred to as firm ware, and are stored in read only memory or flash memory chips. They generally have minimal or no user interface. 2. 1. 3 Advantages of embedded systems: There are many advantages of embedded systems out of which some are as fallows Design and efficiency: The central processing core in embedded systems is generally less complicated, making it easier to maintain. The limited function required of embedded systems allows them to be designed to most efficiently perform their functions. Cost: The streamlined make-up of most embedded systems allows their parts to be smaller less expensive to produce. Accessibility: Embedded systems are difficult to service because they are inside another machine, so a greater effort is made to carefully develop them. However, if something does go wrong with certain embedded systems they  can be too inaccessible to repair. This concern is sometimes addressed in the design stage, such as by programming an embedded system so that it will not affect related systems negatively when malfunctioning. Maintenance: Embedded systems are easier to maintain because the supplied power is embedded in the system and does not require remoter maintenance. Redundancies: Embedded systems do not involve the redundant programming and maintenance involved in other system models. They allow the system hardware to be simplified so that the costs can be reduced. They are designed to do a specific task and have real time performance costaints which are to be met They usually in the form of small computerized parts in place of larger devices which serve a general purpose, so that size can be reduced Enables real-time, deterministic, scheduling and task prioritization Abstracts away the complexities of the processor Provides a solid infrastructure constructed of rules and policies. Simplifies development and improves developer productivity Integrates and manages resources needed by communications stacks and middleware. Optimizes use of system resources. Improves product reliability, maintainability and quality. Promotes product evolution and scaling. 2. 1. 4 Disadvantages of embedded systems: Just like that of a head and tail of a coin, there are also some disadvantages for the embedded systems, they are They aren’t very scalable and in most cases are limited to the components they came with. Though they are only designed to fill a very specific role and I wouldn’t use them in a dynamic, constantly changing environment. They have very few resources at their disposal They are very expensive to repair They do not have any user interface(more often than not) A compiler is necessary on the target and due to compilation during run time, execution times are not predictable. 2. 1. 5 Applications: Embedded system applications describe the latest techniques for embedded system design in a variety of applications. This includes some of the latest software tools for embedded system design. Applications of embedded system design in avionics, satellites, and radio astronomy, space and control systems are illustrated best practice in embedded system design. Embedded system applications will be of interest to researchers and designers working in the design of embedded systems for industrial applications. Military and aerospace embedded software applications: from in-orbit embedded systems to jumbo jets to vital battlefield networks, designers of mission-critical aerospace and defense systems requiring real-time performance, scalability and high availability facilities consistently turn t the Lynx OS-178 RTOS for software certification to DO-178B. Medical electronics technology: five-nine â€Å"availability, compact PCI hot swap support, and hard real-time response-Lynx OS delivers on these key requirements and more for today’s carrier-class systems. Scalable kernel configurations, distributed computing capabilities, integrated communications stacks, and fault-management facilities make Lynx OS the ideal choice for companies looking for a single operating system for all embedded telecommunications applications-from complex central controllers to simple line/trunk cards Electronics applications and consumer devices: As the number of powerful embedded processors in consumer devices continues to rise, the Lynx OS real-time operating system provides a highly reliable option for systems designers. Industrial automation and process control software: Designers of industrial and process control systems know from experience that Linux work’s operating systems provide the security and reliability that their industrial applications require. 2. 2 INTRODUCTION TO WIRELESS TECHNOLOGY:- Wireless technology has been making tremendous progress over the past few years. The ever increasing use of wireless networks serves as an indicator of the progress in the area of wireless networks. The demand for wireless technology is increasing not only in industrial applications but also for domestic purposes. Some benefits of wireless technology are: Completes the access technology portfolio: customers commonly use more than one access technology to service various parts of their network and during the migration phase of their networks, when upgrading occurs on a scheduled basis. Wireless enables a fully comprehensive access technology portfolio to work with existing dial, cable, and DSL technologies. Goes where cable and fiber cannot: the inherent nature of wireless is that it doesn’t require wires or line to accommodate the data/voice/video pipeline. As such the system will carry information across geographical areas that are prohibitive in terms of distance, cost, access, or time. It also sidesteps the numerous issues of ILEC collocation. Involves reduced time to revenue: companies can generate revenue in less time through the deployment of wireless solutions than with comparable access technologies because a wireless system can be assembled and brought online in as little as two to three hours. Provides broadband access extension: wireless commonly both competes with and complements existing broadband access. Wireless technologies play a key role in extending the reach of cable, fiber, and DSL markets, and it does so quickly and reliably. It also commonly provides a competitive alternative to broadband wireline or provides access in geographies that don’t qualify for loop access. CHAPTER-3 3. 1 A BRIEF HISTORY OF 8051 In 1981, Intel Corporation introduced an 8 bit microcontroller called 8051. This microcontroller had 128 bytes of RAM, 4K bytes of chip ROM, two timers, one serial port, and four ports all on a single chip. At the time it was also referred as â€Å"A SYSTEM ON A CHIP† The 8051 is an 8-bit processor meaning that the CPU can work only on 8 bits data at a time. Data larger than 8 bits has to be broken into 8 bits pieces to be processed by the CPU. The 8051 has a total of four I\O ports each 8 bit wide. There are many versions of 8051 with different speeds and amount of on-chip ROM and they are all compatible with the original 8051. This means that if you write a program for one it will run on any of them. The 8051 is an original member of the 8051 family. There are two other members in the 8051 family of microcontrollers. They are 8052 and 8031. All the three microcontrollers will have the same internal architecture, but they differ in the following aspects. 8031 has 128 bytes of RAM, two timers and 6 interrupts. 8051 has 4K ROM, 128 bytes of RAM, two timers and 6 interrupts. 8052 has 8K ROM, 256 bytes of RAM, three timers and 8 interrupts. Of the three microcontrollers, 8051 is the most preferable. Microcontroller supports both serial and parallel communication. In the concerned project 8052 microcontroller is used. Here microcontroller used is AT89S52, which is manufactured by ATMEL laboratories. Microprocessors brought the concept of programmable devices and made many applications of intelligent equipment. Most applications, which do not need large amount of data and program memory, tended to be costly. The microprocessor system had to satisfy the data and program requirements so, sufficient RAM and ROM are used to satisfy most applications . The peripheral control equipment also had to be satisfied. Therefore, almost all-peripheral chips were used in the design. Because of these additional peripherals cost will be comparatively high. 8085 chip needs: An Address latch for separating address from multiplex address and data. 32-KB RAM and 32-KB ROM to be able to satisfy most applications. As also Timer / Counter, Parallel programmable port, Serial port, and Interrupt controller are needed for its efficient applications. In comparison a typical Micro controller 8051 chip has all that the 8051 board has except a reduced memory as follows. 4K bytes of ROM as compared to 32-KB, 128 Bytes of RAM as compared to 32-KB. Bulky: On comparing a board full of chips (Microprocessors) with one chip with all components in it (Microcontroller). Debugging: Lots of Microprocessor circuitry and program to debug. In Micro controller there is no Microprocessor circuitry to debug. Slower Development time: As we have observed Microprocessors need a lot of debugging at board level and at program level, whereas, Micro controller do not have the excessive circuitry and the built-in peripheral chips are easier to program for operation. So peripheral devices like Timer/Counter, Parallel programmable port, Serial Communication Port, Interrupt controller and so on, which were most often used were integrated with the Microprocessor to present the Micro controller . RAM and ROM also were integrated in the same chip. The ROM size was anything from 256 bytes to 32Kb or more. RAM was optimized to minimum of 64 bytes to 256 bytes or more. Microprocessor has following instructions to perform: Reading instructions or data from program memory ROM. Interpreting the instruction and executing it. Microprocessor Program is a collection of instructions stored in a Nonvolatile memory. Read Data from I/O device Process the input read, as per the instructions read in program memory. Read or write data to Data memory. Write data to I/O device and output the result of processing to O/P device. 3. 2 Introduction to AT89S52: The system requirements and control specifications clearly rule out the use of 16, 32 or 64 bit micro controllers or microprocessors. Systems using these may be earlier to implement due to large number of internal features. They are also faster and more reliable but, the above application is satisfactorily served by 8-bit micro controller. Using an inexpensive 8-bit Microcontroller will doom the 32-bit product failure in any competitive market place. Coming to the question of why to use 89S52 of all  the 8-bit Microcontroller available in the market the main answer would be because it has 8kB Flash and 256 bytes of data RAM32 I/O lines, three 16-bit timer/counters, a Eight-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and sup ports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power down Mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next hardware reset. The Flash program memory supports both parallel programming and in Serial In-System Programming (ISP). The 89S52 is also In-Application Programmable (IAP), allowing the Flash program memory to be reconfigured even while the application is running. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.