Design And Implementation Of Wireless Access Control System Based On Visible Light Communication

With the development of LED devices, visible light communication(VLC) is attracting more and more attentions. Visible light communication using LED as transmission source signals. Visible light communication transmits information by loading different intensity lights on the LED.This technology not only enables communication over short distances, but also takes into account the lighting. It transmits information by the way of point to point, so it is very safe. It is also energy-saving, environmental-friendly, produces no electromagnetic radiation, wide spectral bandwidth, and so on. With these advantages, it will has a good prospect. This paper combines visible light communication and door control technology, designs and completes the door control system based on Visible Light Communication.The main work of this paper is as follows:(1) The basic principle of visible light communication, LED light-emitting principle, modulation characteristics and spectral characteristics are analyzed. Several visible wireless channel connections are studied,and established the visible light communication channel model.(2) The hardware of the door control System based on Visible Light Communication is designed in deatail. In light key modules, LED light source device is selected through the experiment, the light source drive circuit is designed independently. In terms of light control lock module, photoelectric detectors is selected, and the receiving circuit is designed independently.(3) The software features are realized based on the design of hardware ciruit. Software is desgined based on the core microcontroller. In light key part, the funcations of key information transmission, human-computer interaction and low-power are realized. In terms of light control lock, the funcations of key information receiver, low-power are realized. After the software is designed, light key and light control lock are packaged.(4) The light key based on mobile phone is designed. The design of light key is divided into two parts, one part is the design of phone APP, the other part is the design of the external hardware circuit. The phone APP is used to send key information to unlock the door. In terms of external hardware circuit, a module of USB signal to TTL signal is desgined, and the information is sended by LED lights.