The Hardware Design Of Digital Video Intercom Connected Networks System Based On Fast Ethemet

Digital video intercom system is the mainstream of the future video intercom products. It is the inevitable result of technology development and the people’s pursuit for a better life. This system is also in line with the requirements of building a conservation-oriented society.The domestic SoC microprocessor Hi3512has been chosen as the core chip of the digital video intercom system in this paper. Hi3512contains an ARM9core, H.264hardware codec, digital video input and output interfaces, I2S audio interface, MII network interface, Flash interface and DDR2SDRAM interface. With the corresponding interface chip or module it is not difficult to realize acquisition, processing, transmission and display of multimedia information.The main content of the paper includes:(1) Discussing the advantages and necessity of digital video intercom system based on the Fast Ethernet network. After the analysis of the Fast Ethernet topology, combined with the equipments’type and installing location, the network structures of building unit and monitoring center are gotten. Assembling them together will obtain a network topology map of the entire housing estate.(2) The requirements of power, reset and clock in the Hi3512are analyzed and the responding circuits are given. Then the JTAG interface, the Flash chip interface, DDR2SDRAM chip interface, audio circuit, camera module, Ethernet interface, keyboard and digital LCD interface are designed. This section focuses on the specifications of various interface above and echo cancelling method by software. Many technical details, such as the design of power supply, the amplifier circuit of microphone signal, auto-lighting circuit of the camera, keyboard circuit, are shared. Finally, the schematics of the video indoor and outdoor units are presented.(3) This section focuses on the fan-out method of Hi3512pins and wiring experiences or precautions of the high-speed signals at the DDR2interface, Flash interface and Ethernet interface. On the basis of the study indoor and outdoor units’ PCBs are designed.