Design of smart home system based on Linux/Qt
A family multi-function control system is designed for the characteristics and application background of smart home . The system adopts the i.MX51 processor of Freescale's ARMCortexA8 series as the MCU, and transplants embedded Linux as a software development platform, and designs a user-friendly interface based on Qt related technology to realize the functions of the ARM board. Module interaction with the server. The system also has digital video intercom, information transceiver, home appliance control, security alarm, home entertainment and other functions.
1 system architecture and function
The home intelligent control system is mainly composed of indoor extension, unit door machine, community wall machine, management center terminal, management center server and accessories. The system adopts a distributed network structure, which can expand the capacity of the system according to the number of households.
(1) The indoor unit is the main platform for users to operate indoors. Its functions are: video intercom, information service, home appliance control, security alarm, home entertainment, etc. The video intercom module mainly implements two-way visual call, video monitoring, message/picture, unlocking, etc. The information service module is mainly used to send and receive property information and cell broadcast, support text and picture form, and realize visual intercom module. Audio-visual sharing; home appliance control module includes wireless control of lighting, curtains, air conditioners, elevators, etc., and presets the situation mode; the security alarm module supports automatic alarms for smoke, door magnet, gas leak detection, etc. The alarm information is transmitted to the user's mobile phone through GPRS/3G technology; the home entertainment module supports the playback of audio and video files in a common format (mainly relying on hardware decoding) and browsing of pictures in a common format (electronic photo frame).
(2) The main function of the unit door machine is to complete the visual call with any household in the unit building and the management center machine. In addition to the message/shadow function, it also provides touch screen calibration, backlight adjustment, password setting and other functions.
(3) The basic function of the wall machine is similar to that of the unit door machine, but the video intercom and message/screen function are for all households in the community.
(4) The central machine is the nerve center of the whole system. The management personnel manage the terminals of each subsystem through the control equipment of the management center. Its functions include: video intercom, video monitoring, viewing alarm information, troubleshooting equipment, information services, System settings, remote management, etc.
2 system implementation
2.1 Qt signal / slot mechanism
Qt is a cross-platform C++ application framework that is fully object-oriented, easy to extend, and allows for true component programming. Qt's C++ class library encapsulates access details for different operating systems, enabling it to be quickly deployed in a variety of desktop and embedded systems [1].
The signal/slot mechanism is the core feature of Qt. This mechanism truly encapsulates the message and completely replaces the original callback and message mechanism. The connection between the signal and the slot is done by the connect() function, which is a static function in the QObject class. The function prototype is as follows:
BoolQObject::connect(constQObject*sender,
Constchar*signal, constQObject*receiver, constchar*member)
Among them, sender and receiver are pointers to QObject, and signal and slot are function names without parameters.
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