ZigBee is an emerging wireless communication technology with short range, low power consumption, low cost and low data rate. The characteristic of smart home is that the network transmits a small amount of data and has low bandwidth requirements, but the required network has good real-time performance, short delay, convenient access, long battery life, high scalability and simple maintenance. This undoubtedly makes ZigBee technology the first choice, because the main application areas of ZigBee technology are industrial control, electronic equipment and building automation. Its characteristics determine that ZigBee technology can meet the needs of smart home systems .
1 system overall plan
The smart home system network can be roughly divided into an external network (Internet), an internal network (ZigBee ad hoc network), and a home gateway. Among them, the home gateway is the core part. The system uses the Boa server ported on the tiny6410 development board as the home gateway, which is responsible for the connection and protocol conversion between the home internal network and the external network. The internal network is described below. The internal network here is the ZigBee self-organizing network, which adopts a tree or star network topology according to the family layout. The ZigBee ad hoc network includes various terminal nodes. These nodes cooperate with relays to control various device switches in the home, such as various electrical switches, temperature and humidity sensors, etc., to achieve remote monitoring. From the communication point of view, each node is a terminal, and they communicate wirelessly with each other through the ZigBee protocol. This does not consider the different protocol conversion issues of the internal network.
The overall structural block diagram of the smart home system is shown in Figure 1.
Figure 1 Overall structure of the smart home
2 smart home gateway design
The home gateway designed in this paper deals with data from the Internet. The hardware required to implement the home gateway must provide strong network support and support the TCP/IP protocol. Therefore, the operating system is required to support multitasking. The home gateway is a functional entity consisting of hardware and software that portes the Boa server to the ARM development board as a gateway. Boa is a single-tasking small HTTP server with open source code and superior performance. It is especially suitable for embedded systems. The home gateway structure is shown in Figure 2.
Figure 2 Home Gateway Structure
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