Software Design Of Terminal Nodes In Gas Meter Reading System Based On WSN

With the development of the times, people's living standard improved and requests a more comfortable living environment. The house of modern people must to be comfortable and meet to living convenience. People oriented and Humanized Design is the theme of the times. As the daily energy residents frequently used, gas is one of the "smart house" necessary conditions. Charges for the gas meter are backward, does not accurately measured. The problem cannot be ignored. The traditional manual meter reading gas fee means have many disadvantages, the data inaccurate, and prone to leakage copy, copying errors and other problems. At present, some regions use IC card prepaid way, to a certain extent, improve the status. But there are still a lot of problems. Firstly, IC card system is difficult to assure the safety. As IC cards are in the hands of the users, gas companies cannot monitor its status, users can easily crack IC card, cause economic loss of Gas Company. Secondly gas companies know nothing about the user's gas flow data, cannot use these valuable user data to develop marketing strategies, cause a large degree of influence of the gas market. Therefore, we need a way to improve the gas meter reading.As the wireless sensor network technology develop and mature, they are used more widely. Wireless sensor networks distributed a large number of sensor nodes in the Monitor area, these nodes form a multi-hop, self-organizing wireless network. the wireless sensor network send the data collected by the sensor nodes to the observer, so the observer can sense the objective world by measured data. Translate the physical world to the digital world. Wireless sensor networks research has become the "hot spots", a lot of organizations and institutions begin related program. Wireless meter reading system for gas based on wireless sensor network technology can collect gas data precisely and rapidly, and send these data to the gas company by wireless sensor network and internet. Gas companies can accurately charge user fees. By analyzing the user data, gas companies can make appropriate market policies, and promote the development of gas market. Gas data are translate by wireless, so there is no need to lay cables, reduce the system cost. Wireless sensor network node design in low-power, Users do not need to change battery frequently.Gas meter reading system is composed by terminal nodes, route nodes, base station and application platform. Terminal nodes are connected to gas Meter. Terminal nodes can control the gas valve and collect gas data and packed the data to wireless message which send to base station. Route nodes forward the message. The base station was connected with the application platform by internet. The application platform storage the data into database. Application platform analyses these data to charging user fees, manage user accounts.The main job of this paper is the embedded software design of the terminal nodes. Program NesC language in the TinyOS. The TinyOS are developed by University of California, Berkeley and Intel Research lab, main application is wireless sensor networks. TinyOS program are designed under component-based architecture, program was composed by modules, each module complete the corresponding function, offer interface to other modules. TinyOS component-based architecture improved the software encapsulation, conducive to the development of programmer. TinyOS use the event-driven , two-level Scheduling and active message mechanism. The program can switch the thread quickly and responded the wireless communications rapidly.The workflow of terminal nodes is divided into three stages, initialization, offline and online status. Node get into the initialization phase after on power. In the initialization node complete the init job, include hardware module initialization and software initialization. After the initialization phase is completed, the node get into the offline status. In the Offline status, the terminal node's main task is to join the wireless network, search for a suitable route node as its parent node. Parent nodes are responsible for the data forwarding of child nodes, and also the command from the base station. After join the wireless network successfully, the terminal node get into the online status. Online status is the normal working status of the terminal node. In this state, the terminal node complete the time synchronization, data collected and upload, and the execute of the command from base station.Current gas market in China, wireless meter reading system is still in the research stage. As the technology immature, there is only a small part of the region use it. But with the wireless sensor network technology continues to evolve and progress, wireless meter reading system be spread throughout the market, to promote the development of the gas market. offer people a more convenient and more humane use platform of gas.