March 29, 2024

Application of remote automatic control system in smart home

The 21st century is a century of informatization. Various communications and Internet technologies have promoted tremendous progress in human civilization. The emergence of the smart home control system allows people to remotely control any electrical appliances (air conditioners, water heaters, rice cookers, lights, stereos, DVD recorders) in the home at any time and any place via mobile phones or the Internet; The air conditioner is turned on, let the water heater boil hot water in advance, the rice cooker cooks fragrant rice And all of this is just a few clicks on the phone buttons or mouse. In addition, the system can also enable families to have multiple functions such as multi-channel alarm, remote monitoring, digital message, etc. If there is a certain kind of dangerous situation, you and 110 can be notified immediately in order to take further action. Comfortable and stylish home life is a sign of social progress. The smart home system can be used for home appliances, home and outside (through wireless LAN at home, telecommunications or the Internet outside the home) without changing any home appliances. Light, power, and home environment can be conveniently controlled, so that people can enjoy the simple and stylish modern life brought by high technology.

1 Working principle of smart home system control

This system is a remote automatic control system for smart home environment based on infrared and GSM networks. Its working principle is as follows: the user sends out a command short message through his own mobile phone, and the GSM module at home receives the command and sends it to the host computer (single-chip computer). The host computer processes the command and transmits the command to the corresponding extension (microcomputer) through infrared After the extension processes the command, it starts the corresponding device, completes the command given by the user and replies to the host. After receiving the response, the host sends a reply short message through the GSM module to report that the user has completed the command. If the host computer does not receive the reply message of the extension within the specified time (here, time is 60s), the operation is deemed invalid and the invalid message of the reply operation is sent to the user's mobile phone, requesting the user to reissue the command. If the received short message is wrong, the host will immediately reply to the user that the operation is invalid and request to reissue the command. The system structure is shown in Figure 1.

Figure 1 System configuration diagram

2 Hardware design

2.1 MCU and GSM communication module

This MCU communicates with the GSM module through the RS232 serial communication interface, extracts short messages from the GSM device, sends relevant information, and connects to the infrared module through the serial communication interface. The infrared module is used to achieve communication between the main unit and the extension. Therefore, Use AT 89S52 chip. Two serial interfaces are needed for control, but 89S52 has only one serial port, so analog serial interface communication is also required in the program. The simplest external wiring circuit is shown in Figure 2.

A T 89S52 External wiring

Figure 2 AT 89S52 external wiring

89S52 and TC35 communicate through asynchronous serial interface, the communication rate is 9 600b? S, with 1 start bit, 8 data bits, 1 stop bit, no parity.

After the MCU is started, the AT + CM GD = 2 command is issued to clear the data in the second storage space, and then the command is continuously issued to read the second storage space. If there is data, it means that the data has been received, and the data will be processed, and then the spatial data will be deleted after processing. When the MCU sends a short message to the mobile phone, the MCU sends a series of commands of AT, AT + CM GF = 0, AT + CM GS = X to the GSM module. After receiving the reply message, the content of the short message is finally sent.

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