Research And Design Of Smart Switch Based On ZigBee Wireless Sensor Network

With the development of the Internet of Things (IoT) technology, more and more attention has been paid to IoT applications. Among them, the concept of smart home has been gradually penetrating into our daily lives. Smart home can not only provide convenient and comfortable life for us, but also convert the original passive structure of living environment to an initiative one, realizing the full-ranged information interaction between residents and the living environment. Therefore, studying smart home system has great practical prospects.In this thesis, a household smart switch system is studied and designed based on ZigBee wireless sensor network (WSN) and ARM11 technology with the analysis of current WSN and smart switch technologies. This system, integrated with General Packet Radio Service (GPRS) technology, can support remote monitoring function by using a cell phone. The designed system includes nodes in three-level structure: main controller, group controllers and switch nodes. The main controller, the highest level node in the system, contains an S3C6410 microprocessor as the kernel, runs Windows CE operation system, and serves as the home gateway. It keeps monitoring the status of all smart switch nodes and enables the remote monitoring function by cell phone via the GPRS access technology. The group controller is the middle level node in the system. It binds a group of smart switch nodes in one room and monitors them as one node. The smart switch node is also called end device. It is made up of ZigBee module, buttons, LED status display module, relay module, and over-current protection circuit. The smart switch node lies at the lowest level and controls electric equipments directly.The illumination switch system is the most basic smart switch system in a smart home. It can be adapted to other systems (for example smart electrical outlet system) by easily making minor revisions. Thus the illumination switch system is taken as the example for focused research in this thesis. The design method of smart switch based on ZigBee WSN, as well as the working mechanism and functions of different parts of the system, are firstly introduced. Then the hardware and software implementation of the main controller based on ARM11 system and the smart switch nodes are presented. Finally, functions of the whole developed system are tested and analyzed. The software of all ZigBee modules are based on ZStack-CC2430-1.4.2-1.1.0 provided by Texas Instruments, and improved in the developing platform of IAR embedded workbench for MCS-51 v7.20H. Major improvements include receiving and sending methods of periodical signals and transmitting strategy of reporting messages. An active method to discover the current topology structure of the ZigBee network is also designed. The software design is focused on the application layer of the protocol stack of each functional node to realize their specific functions in the developed system.The smart switch system should be able to provide nine functions such as the real-time status display, local manual control, remote monitoring, local and remote lock, shutdown-all (group-off), over-current protection, night light display, sound-controlled delay and security functions. Network construction tests of the designed system are performed in a typical three bedroom apartment. Results indicate that the smart controlling of switch groups can be realized by the main controller, and most other functions have been achieved. Applying this smart switch system can not only save power, extend the lifetime of electric equipments and increase their efficiency, but also provide better human-friendly living experiences. In the current wave of constructing"smart planet"and"smart home", the smart switch system will be the major developing tendency of both home and industry switches.