Design Of A Highly Flexible Wireless Intelligent Switch

With the rapid development of society and economy, smart home products have come into our lives. There is no clear definition of smart homes in the industry, and generally smart homes are considered to include intelligent appliances, smart switches, smart security monitoring, information intelligence, intelligent life etc. Smart homes cannot work without smart logic control, therefore, this paper starts from the fundamental equipment of smart homes—the smart switches and mainly accomplishes the following work.First, the relevant literature information about smart homes is studied and the current studies of smart homes at home and abroad are discussed. After the analysis on several existing products of smart switches, some problems have been found:wired products need re-cabling and are hard to deploy; wireless products don’t have standard wireless protocols, satisfactory security and limited configuration of mutual control. So a newly designed wireless smart switch is proposed to provide highly flexible mutual control.Second, after comparing several wired and wireless protocols of smart homes, it can be found that ZigBee provides self-organization, high security and support for many more nodes. In this paper ZigBee is used as the communication protocol. Meanwhile, ZigBee, IEEE 802.15.4 and TI z-stack are all studied in detail.Third, some major problems of smart switches are discussed in this paper, such as binding, mutual control, I/O status notification, network security and power supply. Binding is the basis of mutual control, switches can only establish a relation by binding, and a relay binding through a third node is presented in this paper. For the mutual control, the logic truth table is used to study the switch control and the logic function is used for complex logic control. For realizing the logic function, the ladder diagram and IL instructions are introduced, and IL coding mechanism is designed for the interpretive execution of the logic function in the switch node, so that the mutual control is realized. Because during the process of mutual control the I/O status of the controlled switch and logic-related switches must be known, a I/O status notification status is designed in this paper which can help the switch nodes get I/O status from each other. The security problem is also taken into consideration in this paper, the modification of PANID and signal channels can achieve a simple network protection. Besides, the AES-128 encryption and CCM operation included in the protocol stack are used for the information security. In the survey of existing products a problem has been found. The switches on the wall only have the live line and control line, so it is difficult to power the smart switches and influence the switch modification. Against this problem Studied the existing solutions.Finally, a complete framework of smart switches is presented and tested in this paper. The framework includes the hardware and software implementation of smart switch gateways, smart switch nodes, smart sockets and the smart remote controller. A PLC is used to verify the logic control, and the test nodes are used to verify the relay binding and communication distance. The experiment results show that the requirements of mutual control are met and ZigBee is suitable for the remote control in smart homes.