Research And Design Of Smart Home System Based On 433MHz RF Communication

Smart home is a hot research topic in application of Internet of Things, smart home integrates wireless communication technology, computer technology, wireless sensor networks and other advanced concepts, to provide people with comfortable and safe living environment. At the same time, there are many problems in the smart home industry, such as the lack of standards and norms, centralized control of the smart home ecosystem being not formed, high cost of smart home products.Due to the internal home network establishment and communicating demands,such as cost sensitive, low transmission rate, short communicating range, in this paper,based on 433 MHz RF communication, a type of low cost, low complexity, extensible smart home system solution is presented and a system experimental platform is set up.The users can access the intelligent gateway through the terminal device, land smart home system management platform established in embedded Web server, send home appliances control command or view the internal state of the family, then the intelligent gateway receives the control command and processes it and interacts with the home appliances through the internal home network(433MHz RF network). The main contents of this paper are as follows:(1) In the aspect of 433 MHz RF communication, the communication process of433 MHz RF module is studied based on CC1101, the CC1101 driver is designed based on the SPI driver framework of RT Thread operating system.(2) In the aspect of intelligent gateway, in order to realize the centralized control of home appliances and integration of heterogeneous networks, a gateway based on the embedded operating system called RT Thread and the 32 bits ARM chip called STM32F407 are implemented. The intelligent gateway is equipped with CC1101 RF module, ethernet module and other functional modules, which not only realizes the intelligent control of home appliances, but also realizes the integration of heterogeneous networks.(3) In this paper, the 433 MHz RF protocol stack is research focus, which is studied and designed based on CC1101 and RT Thread operating system, it mainly contains the following contents: multithreading communication model, the definition of 433 MHz RF communication protocol and node model, self construction of 433 MHz RF networkbased on tree topology, its main task is to achieve related functions of 433 MHz RF network and home appliances intelligent control. This protocol stack adopts the separation mechanism of kernel space and user space, these two spaces communicate through the API function, which not only ensures the security of the protocol stack, but also simplifies the program design.In the aspect of application, the small TCP/IP protocol stack LwIP is configured to build embedded Web server and realize smart home system based on B/S framework. At last, the system is tested to verify the functions of home appliances control and status reporting, RF network self construction, embedded Web server and so on, and suggestions for improvement and next-phase work are presented.