Research And Design Of The Audio-video Switcher Based On Internet And Cortex-M3

With the continuous development and progress of the radio and television broadcasting cause. The radio and television broadcasting is no longer a single model, but rather the full three-dimensional model, which focus on the ground wireless coverage, cable transmission, the Internet network and satellite transmission. In order to adapt to the change, we need to implement digital broadcasting, one of the key device is the audio-video switcher which is based on the matrix as the core component and used to control the input and output channels of audio-video signals. Along with the development of embedded technology, especially the development and application of the embedded Internet technology, which provides a new approach for developing a device with network function. Therefore, the development of digital audio-video switcher which is based on the technology of Internet control has important practical significance for the promotion of the development of the radio and television broadcasting cause.This thesis studied the feature of the former switcher, against the feature of signal inputting individually, adopting ordinary control operation, running slowly and some other deficiency, it also analyzed the functional requirement of the digital audio-video switcher. The author designed an audio-video switcher based on the Internet and the CPU of ARM Cortex-M3.The paper described the whole system in three part, they were theory, hardware and software. In the part of theory, the paper described the matrix switch and control theory and the embedded Internet technology in detail, especially described the widely-used TCP/IP protocol, analyzed the LwIP protocol which is dedicated to the embedded devices and used in our system, additionally, studied the Real-time of the network communicaiton. In the part of hardware, the paper introduced and analyzed each functional module of the system in detail, including ARM minimum system, key and LCD display circuit, USART and Internet communication circuit, data storing circuit, signal conditioning circuit and the system power circuit. In the part of software, the paper introduced the flow of the main program, analyzed the interrupt and control program, including the key control program, the Internet command control program and USART command control program. In the Internet command control program, the paper described the design of the command receiving and accepting program in detail, which is operated in the embedded TCP/IP protocol-LwIP.More than one year has been spent to design the hardware and software, we have successfully built a8×2audio-video switcher(8input signals and2output signals) based on the Internet and Cortex-M3, it was able to switch and control the audio signals, standard definition digital video signals and high-definition video signals, additionally, it also can realize Internet remote control. The test result show that the system function, reliability, stability, real-time can meet the design requirement, the system has some practical value in the field of radio and television broadcasting.