Smart home is based on residential platform, using integrated wiring technology, network communication technology, security technology, automatic control technology, audio and video technology to integrate home life related facilities, and build efficient management system for residential facilities and family schedules. Home safety, convenience, comfort, and artistry, and achieve an environmentally friendly and energy-saving living environment.
The most commonly used applications are lighting, water heaters, air conditioning, intrusion monitoring, smoke alarms, video surveillance and intelligent control of curtains.
1. Communication technology in smart home
1.1 Comparison of wired communication control and wireless communication control
The communication technology in the smart home can be divided into wired communication technology and wireless communication technology.
(1) Wired control
The structure of the wired control is to place the controller in a strong electric box, and the switch and the central control host are respectively controlled by the weak electric control line. Wired control uses wired communication technology.
Advantages of wired control: safe and stable, undisturbed; shortcomings of wired control: high requirements for the program, high requirements for line erection, and difficult to expand and change later. This method is used in the early stage of the development of smart homes. It is a change from industrial control. It is mainly used in large-scale commercial places and other places where people have centralized management, and is gradually replaced by wireless communication.
(2) Wireless control
Wireless control uses wireless communication technology to achieve control of the device. Advantages of wireless control: simple installation and wiring; shortcomings of wireless control: anti-interference is worse than wired control, and signal coverage is affected by buildings.
1.2 Wireless communication technology in smart home
The wireless communication technologies in smart homes mainly include:
1 infrared communication technology;
RF technology less than 1 GHz, such as 2433 MHz;
3 Bluetooth technology;
4ZigBee communication technology;
5Z-Wave technology;
6WiFi technology.
Each technology has its advantages and disadvantages, but regardless of the communication technology used, if you want to achieve remote control of home equipment, the equipment needs to access the Internet. The WiFi communication technology is the mainstream technology for the handheld terminal to access the Internet. Devices that use other communication technologies other than the WiFi technology need to be converted by the home gateway to access the Internet, for example, using ZigBee.
The smart home system of technology needs to add ZigBee to WiFi in the home gateway.
The main advantages of WiFi technology in smart home applications are: WiFi intelligent nodes can directly connect to wireless routers to access the Internet; no need for home gateways, nodes can be arbitrarily expanded; will not destroy existing decoration; smart phones can carry out local area networks Control and remote control.
Of course, WiFi technology has its shortcomings compared to ZigBee and 433MHz RF communication technology: power consumption is too large and price is high. However, with the introduction of energy-saving technologies and improvements in chip technology, power consumption and price issues have gradually been resolved. Since the WiFi module is a standard configuration for notebooks, tablets, and smart phones, smart homes based on WiFi technology will gradually be promoted and applied, and the market prospect is broad.
The following focuses on the serial WiFi module to illustrate the application of WiFi in smart home.
2, serial WiFi used in smart home
2.1 Serial WiFi Overview
The WiFi module or the WiFi network card used on the computer needs to run on the basis of the operating system, and the hardware resources of the host are very high. For example, the general industrial equipment and the household electrical equipment cannot directly drive such a WiFi network card.
The serial WiFi module, also known as the embedded WiFi module, is a WiFi module with embedded TCP/IP protocol. The hardware component is mainly composed of a built-in single-chip microcomputer and a WiFi module. The single-chip microcomputer must implement the bare-metal driver and TCP/IP protocol, and the WiFi module must complete the wireless transmission and reception of data. The embedded WiFi module provides a UART serial port or an SPI interface, so that it can be connected to the MCU through a serial port or an SPI interface, so that the device can easily access the Internet.
Figure 1 is the SWM9001EU serial WiFi module developed by Lingxin Microelectronics Technology (Suzhou) Co., Ltd. using the WiFi chip of the company's independent intellectual property rights. The module integrates the TCP/IP protocol stack and WiFi module, and the user can easily realize the wireless of the serial device. Network function, saving development time, enabling products to enter the market faster and enhance competitiveness. The module can be widely used in oil fields, mining, industrial, smart home and Internet of Things. The mechanical dimensions of the module are 33 mm x 20 mm x 4.5 mm.
2.2SWM9001EU serial WiFi function and indicators
A smart home composed of WiFi smart socket
(1) Basic functions
1 single operating voltage is 3.3V;
2 working current <250mA (operating current <25mA in energy-saving mode); sleep current <2mA (SwitchoffWiFipower);
3CPU clocked at 120MHz, embedded with Flash256KB, SRAM96KB;
4 two working modes are command control mode and transparent transmission mode;
5 complete WiFi wireless communication solution to reduce the resource requirements of the application processor;
6 kinds of configuration methods include built-in WEB configuration server, PC configuration software configuration or SCI_AT+ command configuration and mobile phone configuration;
7 serial port baud rate is up to 115200bps.
(2) WiFi indicator
1 WLAN standard is IEEE802.11b/g, 2.4 GISM band;
2 Support Ad-Hoc mode to set up a wireless network;
3 Support WEP40 and WEP104 encryption (64/128 bit), support WPA/WPA2PSK encryption, encryption algorithm supports AES and TKIP;
4 WiFi connection is automatically restored after disconnection;
5 The time from reset to the establishment of the WiFi network is less than 5s (WEP encryption mode) or 10s (WPA encryption mode).
(3) Built-in TCP/IP protocol
1 Support DNS domain name resolution service;
2 Supports DHCP to automatically obtain an IP address, and automatically activates the DHCP server function in Ad-Hoc mode;
3 support network data transmission protocol TCP, UDP;
4 support TCP server mode or client mode;
5 As a TCP client, it has a TCP disconnection automatic reconnection mechanism to ensure stable and reliable data transmission links;
6 as a TCP server, allowing connections of up to 8 clients;
7 supports UDP broadcast or unicast.
The following describes a specific example of a WiFi socket as a serial WiFi module.
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