In recent years, the Internet of Things technology has developed rapidly, and the level of informationization in the whole society has continuously improved. Smart home is one of the main applications of the Internet of Things, and has become a hot research field and the future development direction of home life. It can provide users with a comfortable and convenient living environment. However, since most of the related products on the market are expensive, the penetration rate is still low. In the past, exploration and development often stayed on the transformation of electrical equipment itself. This attempt made smart home products once a luxury. This paper introduces a power control system, which is an important part of smart home. It realizes the remote automatic control function without changing the original electrical equipment.
1 system structure
The power control system is composed of a remote controller and a socket node, and its working principle is shown in FIG. 1 . When the user is at home, the socket is controlled by radio frequency through the remote controller. After receiving the signal, the socket node decodes by the microcontroller, and according to the result, the specific number of sockets are turned on and off, so that the connected electrical appliances are activated or turned off. When the user is far away from the residence, the mobile phone short message can be sent to the remote controller through the GSM network. After the microcontroller reads the information, the information is transmitted to the indoor wireless network through the radio frequency chip, so that the socket at the corresponding address is controlled. . It can be seen that the remote controller belongs to the gateway node in the whole smart home system . On the one hand, it forms an indoor radio frequency local area network with the socket node, and on the other hand, it is connected with the GSM network, and extends the remote control distance. The internal structure of the remote control is shown in Figure 2. It includes the temperature and humidity detection circuit, clock module, nRF905 RF transceiver module, GSM module and other functional circuits. These modules are connected to the control core LM3S811. The microcontroller uses the ARM Coaex-M3 architecture. Due to the high-density Thumb-2 instruction set, the memory overhead is greatly reduced, and the migration of the operating system is more convenient.
Figure 1 How the remote control socket works
Figure 2 Remote control block diagram
The socket node mainly realizes the radio frequency communication with the remote controller and the on/off control of the relay, and its structural block diagram is shown in FIG. 3. Smoke sensors in the socket are used to prevent fire hazards. Once smoke or flammable gas is detected, the corresponding relay on the socket will be disconnected and reported to the remote controller through the RF transceiver module. After receiving the information, the remote controller will promptly remind the user to take corresponding measures through the SMS function of the GSM module. Prevent the occurrence of danger or further expansion of property damage. Due to the small amount of work at the socket end, the system uses the STC12C5620AD microcontroller as the main control chip of the socket end in terms of cost and performance.
Figure 3 block node structure block diagram
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