Remotely Controlled Heating System - Assignment Example

Remotely Controlled Heating System Introduction: Technology advances in microprocessors and computer networks have openedthe doors to development of thousands of embedded systems. Embedded systems are designed and engineered towards the manipulation and execution of some specific task. Embedded systems provide high performance and low cost due to their dedication to their assigned task. Automatic control over various equipments could be achieved using modern computer technology. Communication technology extended the range of automated control endlessly. The Task to do: The task to be completed is the design of an embedded distributed network system. The client hardware such as mobile phones or a Personal Digital Assistant (PDA), which is connected to mobile network, is to send and receive messages from a Personal Computer (PC) that is connected to the Internet. The home PC is located inside the house and is also connected to all room temperature devices through a wireless network. The PC send read or set messages to the temperature sensors as to read or set the temperature of any room. The Problem to Overcome: The home PC must be able to connect to each room temperature device. A network media and protocol must be established to ensure the efficiency and reliability of such connection. The PC application program must be able to access database values of required temperatures and current temperatures and must be able to send the correct commands to increase/decrease temperature as required. The home PC must be able to receive and send messages to the mobile phone or PDA. The PC must have a static address for the client hardware to contact when needed. Messages from the mobile network protocol must be translated to the TCP/IP internet protocol as to ensure successful transmission and reception of requests. The Solution: Three-tier architecture is used to allow the various components of the distributed network to communicate and relay messages to each other. The three tiers are: Server, Client, and the database Figure 1: Architecture of Remote Controlled Home Heating System The Server: The server is a Personal Computer (PC) that is connected to wireless switch. The wireless switch is connected to the wireless sensors that are located in each room of the house. The switch is connected to a DSL router that connects the wireless home network to the Internet. The server PC operates a Windows XP operating system. Two server application programs are loaded and run on the server PC every time the server operating system is fired up. The first server application is responsible for communication with the client. The second server application is responsible for communication with room temperature sensors. A database is created, maintained and run on the server PC every time it starts. The database contains the passwords to allow access to the heating system. The database contains all the preset schedules the user has selected to be run during different times of the day. The first server program takes care of communication with clients. It listens to client messages on a selected TCP port. Once a message is received from the client on the selected TCP port, the message is decoded. 1. The message is decoded to extract the following information password, type of message, selected room, and required temperature to be set if it is a an order message. 2. The privilege to access the server is checked by comparing the password decoded from the message against all stored passwords retrieved from the database. 3. The type of message is next determined. 4. If it is a read message, the database is queried to retrieve current selected room temperature. 5. If it is a change temperature order, the database is accessed to change the goal temperature of the selected room. 2. The second application program is used to communicate with room temperature sensors. It polls the sensor of each room using wireless communication and save the read temperature in the database. It also queries the database to extract and compares desired room temperatures against actual room temperatures. If desired room temperature is different from actual room temperature, it issues a command to this room temperature sensor to make necessary changes to Air Conditioner controls. If all current room temperatures match the desired temperatures, a message is sent to the client informing it that all temperatures are set as required and home is ready for your reception. The client The client could be a mobile phone or a hand held Personal Digital Assistant (PDA). The client is connected to the mobile network. The client operates an embedded operating system which is the .Net embedded. The client loads and run a client application program every time it is started. The application program enables the user to perform one of two functions. The user could read the current temperature of any selected room. The user could change the desired temperature of any selected room. To perform any of either function, the client application program sends a message through the mobile network to the internet. Once the message is on the internet it gets routed to the static Internet Protocol (IP) Address of the home heating server. The message uses its pre-selected TCP port address to deliver the message to the server. Another client application is run on the client which listens on a selected TCP port for any messages from the server. The server sends messages to the client to inform the client when all desired temperatures are set in all rooms of the house. The Database The database holds the current and desired temperatures for each room. The database also stores schedules for the Home PC server to follow in case remote access is not employed. System Operation: The PC reads, display and control the temperatures of all rooms in the house. The PC is connected to the room temperature devices through a wireless network. The PC could also be remotely controlled using mobile phones or PDAs. Mobile phones and PDA's send messages to the PC to read or set temperature of any room of the house. The message that originates from the mobile phone goes through the mobile network and then to the Internet to reach the PC. The mobile phone or PDA remotely control or read room temperature devices inside the house. In case of network failure the PC second application program continues to retrieve and compare required temperatures to current temperatures and issues set commands to room temperature devices as necessary. Top Level Requirements of the Remotely Controlled Heating System: 1. The temperature of any room of the house could be read from a mobile phone or PDA running the embedded client software. 2. The temperature of any room of the house could be set from a mobile phone or PDA running the embedded client software. 3. The home PC issues required heating commands to room temperature devices according the required temperatures stored in the database. 4. The home PC informs the client mobile phone and PDA when all required temperatures are set and home is ready. Future Technological Trends: It is required to improve the performance of networked embedded system while maintaining cost lower or similar levels. WiMAX and new VMEbus standards are two examples of future modifications that would affect the future of Networked Embedded Systems. VMEbus Standards VMEbus International Trade Association (VITA) is renewing VersaModular Eurocard bus (VMEbus) architecture. VMEbus is a computer bus standard that was originally designed by Motorola VMEbus system uses Eurocards, which are European designed circuit boards. Cards are plugged into a backplane which have up to 21 slots for different cards. VMEbus enables us to build embedded computing systems that are scalable, modular and operate in real time. VMEbus enables us to add a card when needed without making changes to the systems. VMEbus Switched Serial (VXS) new standard enables the parallel VMEbus to support switched serial fabrics while maintaining backward compatibility with the existing backplanes. Combining the parallel bus with switch fabric technologies for multi-point, high-speed data transfers creates choices for embedded computing designs of all types (VITA 2007). Future enhancements in speed and interoperability of the buses interconnecting microprocessors and peripherals would ripe more efficient embedded systems. Higher levels of bus performance would provide higher raw data bandwidth to support higher peripheral device. Low performance devices would still be used by placing them on lower performance buses which are then bridged to the higher performance buses (Rapido 2007). Worldwide Interoperability for Microwave Access (WiMAX) WiMAX is intended to provide Wireless Metropolitan area Newtorks (MAN). It can provide broadband wireless access up to 50km for fixed stations and 15km for mobile stations. In contrast the WiFi wireless local network (LAN) standard is limited to 100m (WiMAX 2007). WiMAX provides a connection at the physical layer of the Open System Interconnection (OSI) network model. The technical features of the communication protocol between towers and WiMAX devices are defined in the 802.16 specification. WiMAX supports two types of connection. Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD). IN FDD, the base station transmits at one frequency and each subscriber station responds back at another frequency (figure 2). In TDD, One frequency is used for communication between the base station and all subscriber stations. The base station sends at certain time slots and the subscriber stations respond at specified time slots (figure 3). Figure 2: Frequency Division Duplexing1 Figure 3: Time Division Duplexing1 Each node (tower/access points) of WiMax can communicate with each other, Range and reliability is extended as there are multiple routes a signal can take. WiMax new standard 802.16m is expected to transfer data up to a rate of 1 Gigabit/second while still maintaining backward compatibility with existing infrastructure (Future WiMAX 2007). WiMAX is expected to extend the range of the widely spread WiFi network. WiMax would connect the already established WiFi Local Area Networks to create a Wireless Metropolitan Area Network with longer range, higher bandwidth and more reliability.. References Future WiMAX. Retrieved March 15, 2007 from http://21talks.net/voip/wimax-next-generation RapidIO: An Embedded System Component Network Architecture. Motorola Semiconductor Product Sector. Retrieved March 14, 2007 from http://www.mc.com/literature/literature_files/rapidio-wp.pdf Mercury computer Systems. Technology Standards. Retrieved March 15, 2007 from http://www.mc.com/technologies/standards.cfm VITA. Open standards. Retrieved March 14, 2007 from http://www.vita.com. Weiser, M. (1991). The Computer for the Twenty-First Century, Scientific American, pp. 94-10. What is WiMax. Retrieved March 14, 2007 from http://www.wimax.com/education WiMAX. Retrieved March 15, 2007 from http://nislab.bu.edu/nislab/education/sc441/JustinKen/JustinKen/Networking%20Webpage/index_files/Page735.htm Read More