Design Of HDMI Interface Based On ARM9

With the popularity of high-definition digital TV, traditional analog audio and video interface can not meet such a huge amount of data transmission. Meanwhile, the digital display device using the analog interface requires two operations such as D/A and A/D conversion, which will reduce the quality of the image. HDMI interface adopts TMDS transition minimized differential signaling, and its unique encoding and transmission timing allow to send all-digital high-definition video signals which are not compressed, including multi-channel audio and a variety of control data, so it can overcome the defection of the traditional analog display effectively. Therefore, the development of the HDMI interface device has a very important practical significance.Firstly, the paper comprehensively compared the characteristics of several common analog and digital audio and video interfaces, then the paper has a brief summary of the development status of the HDMI interface, and it has stated the significance and function of the HDMI interface devices; on the basis of in-depth study of the HDMI specification, it summarizes performance characteristics of the HDMI, introduces the TMDS signal transmission principle, the HDMI signal operating mode and code, briefly introduces the video signal type supported by the HDMI interface and the features of the HDCP authentication encryption.Combined with the function requirement of the HDMI interface device, the paper uses S3C2440based on ARM920T kernel as the main chip, S3C2440controls the work of HDMI transmitter AD9889B through the IIC interface, and connects the LCD controller output interface with the AD9889B video input capture module; In order to enhance the anti-static and anti-jamming capability of the HDMI interface and improve the integrity of the high-frequency signal, we give full consideration to the rules of the board trace between the AD9889B and HDMI port and join the CM2020protection chip.According to the hardware structure of the HDMI interface, the paper puts forward a perfect software design method. When the S3C2440video source has been initialized and the display device has been properly connected, AD9889B completed the initialization and EDID information read operation, and configured the video input and output mode, then S3C2440get test image from Nand Flash and transformed into standard video format through LCD controller, AD9889B automatically captured video and transformed into the HDMI video signal, then sent to the digital display device after HDCP encryption.In order to verify the performance parameters of the HDMI interface, a lot of testing work has been done in the paper. Finally this paper summarizes the work completed and introduces what the system needs to be improved.