Design of Intelligent Home Remote Control System Based on ARM

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With the continuous popularization of Internet technology and information and communication technology to ordinary families, how to integrate consumer electronics, computers and communication has become a matter of great concern. The intelligent home appliance network management system can realize the networked and intelligent management of household appliances. Through the system, the network appliances in the home are connected to the Internet and the GPRS network, so that the user can remotely operate the home appliances through the system whenever and wherever. This paper mainly discusses the design and implementation of smart home remote control system.

The overall structure of the smart home system

The core part of the smart home remote control system is an embedded web server. The system integrates wired and wireless web servers. Users can log in to the home web server using the office PC or mobile phone. After verifying by username and password, they can view it. And control the household appliances; the system has an LCD and a keyboard, and has a good human-machine interface; the user can also set the tasks of the system through the keyboard; the system has a rich function expansion interface, through which the fire-proof security can be realized in the future. And applications such as smart meter reading. The system structure block diagram is shown in Figure 1.

Figure 1 The overall structure of the smart home system

Hardware design of smart home system

1 system hardware structure

In this system, the main chip uses STMicroelectronics' STR710, which is based on the high-performance ARM7TDMI core and has a very rich set of peripherals and enhanced I/O functions. The device includes on-chip high-speed single-voltage flash memory and high-speed RAM memory. Compatible with all ARM tools and software due to the embedded ARM core. The network chip adopts the ISA-based low power consumption and superior performance of the CS8900A produced by Cirrus Logic. The GPRS module adopts the MC35i of Siemens. In addition, the system also provides 32Mb of Flash and SRAM, which are realized by the chips M28W320ECB and TC55V820FT respectively.

Figure 2 system hardware structure

2 main chip STR710

With four channels of 12-bit ADC and 10 communication interfaces, the STR710 is ideal for industrial applications, especially for this design, which requires more interfaces, both analog inputs and digital inputs.

The STR710 is the heart of the entire system. As an embedded gateway, it connects the external network with all network appliances and is the platform for the entire system to run. First, in remotely operating the home appliance, the STR710 is responsible for extracting the user command from the short message received by the MC35i and the Ethernet data received by the CS8900A, and then operating the corresponding network appliance or querying its operation according to the instruction, and finally executing the result. Feedback to the user terminal. Secondly, in terms of network appliance working mode setting, the task of STR710 is mainly to display the corresponding menu and help information on the LCD, and guide the user to complete the setting through a good interface. The STR710 also regularly checks the operation of the home appliance. In the event of an emergency or dangerous situation, take the necessary protective measures in a timely manner and alert the user terminal.

3 Network Controller CS8900A

The prominent feature of the CS8900A is its flexible use. Its physical layer interface, data transmission mode and working mode can be dynamically adjusted according to needs. The internal registers are set to adapt to different application environments.

CS8900A supports I/O transfer mode, Memory mode and DMA mode. I/O mode is the default mode for accessing CS8900A memory area. It is relatively easy to use, so I/O mode is selected in this system. The hardware connection block diagram of CS8900A and STR710 is shown in Figure 3. STR710 realizes the working mode control and read and write operations of CS8900A through control signals such as /SBHE, /IOW and /IOR. The data is received in the interrupt mode. Since the interrupt levels of the CS8900A and STR710 are reversed, a NOT gate is required between the interrupt signal lines. The data transfer between the CS8900A and the STR710 uses the default I/O mode. Therefore, the read/write pins /MEMW and /M EMR are set high to turn off the Memory mode. In this mode, access to all registers is achieved with four address lines. As shown in FIG. 3, the pins SA0 to SA3 are connected to the address lines A11 to A14 of the STR 710. In addition to ensuring the above default offset address (0x0300), SA8 and SA9 must be set high, and the remaining unused address lines are tied low.
The CS8900A sends the data to be sent by the CPU to the network via an isolation transformer (E2023) with an e-current coil. When receiving data, the data from the network also passes through the isolation transformer. The function of the isolation transformer is to separate the external circuit from the CS8900A to prevent interference and burnout of components, and to realize the plugging and unplugging function.

Figure 3 Interface between CS8900A and STR710

4 GPRS module MC35i

The normal operation of the MC35i requires a corresponding peripheral circuit to cooperate with it. The 40 pins of the MC35i are connected to the power supply circuit, the startup and shutdown circuit, the data communication circuit, the voice communication circuit, the SIM card circuit, the status indicator circuit, etc. through the ZIF connector, as shown in FIG. 4 .

Figure 4 MC35i peripheral interface circuit

System software design

The system software adopts a layered design, including a hardware device driver layer, an operating system layer, an application program interface layer, and an application software layer. The software system structure is shown in Figure 5.

Figure 5 Software framework of smart home appliance network management system

The operating system chooses a small real-time operating system μC/OS-II based on the following considerations: completely free kernel, open source code, system kernel is highly practical, high reliability, operating system kernel to processor and ROM, The RAM resource requirements are not high, which is conducive to porting on a 16-bit microprocessor. The TCP/IP protocol is divided into four layers: link layer (ARP protocol), network layer (IP protocol, ICMP protocol), transport layer (TCP protocol, UDP protocol), and application layer (HTTP protocol). The TCP/IP protocol stack of this system selects uIP1.0; the graphical user interface selects μCGUI.

Conclusion

This smart home remote control system design is different from the previous focus on security, but the overall solution of home information. The hardware composition and structure of the system are given, and the connection mode of key modules is given. And a block diagram of the software implementation. Due to the rich interface of the system, with the development of broadband wireless communication technology, Internet technology and microprocessor technology, the functions of the system can be continuously supplemented and improved. Taking the burglar alarm as an example, the camera is installed at home, and the embedded system is used as the video central processor to complete the video compression and recognition, and real-time monitoring and alarming of the home can be realized. It can be seen that the smart home system currently has broad application prospects.