Design And Implementation Of USB Sound Card Based On DSP

Intelligent audio and video terminals are widely used in multimedia conference systems,remote classrooms and other systems,and the USB-based sound card interface module is a key component for audio streaming between it and the computer system.As a portable audio terminal interface,the USB sound card module can meet the application requirements of a variety of scenarios,and has better sound quality performance than traditional sound cards.Based on the USB2.0 protocol,the USB sound card implements the UAC(USB Audio Class)protocol framework and HID interface.The USB sound card module based on TMS320C6748high-performance DSP is designed and implemented,and the graphic equalizer algorithm is completed.The main work of the paper includes:1.Research on sound card module hardware and USB protocol.The hardware framework of sound card module is designed,including hardware interface,communication protocol and memory technology;then the USB2.0 protocol is studied,including the principles of USB data transmission,device identification and device request;secondly,the audio control interface,audio streaming interface,and audio device request in the UAC protocol are analyzed;finally,the transmission principle,operation mode and control method of HID protocol are studied.2.Design and implementation of USB sound card module.Firstly,the hardware path of the sound card module is designed,in which the sound collection and restoration are completed by the codec,and the DSP transmits the audio stream through the multi-channel audio serial port and the codec,and uses the I2 C bus to control the codec;then the software framework and protocol stack of the USB protocol are designed and implemented,and on this basis,the descriptor structure of the USB device is designed and complete device functions are realized;secondly,the audio topology,audio stream and audio control interface are designed for UAC to realize the functions of audio data transmission and audio control,the report structure and interrupt transmission channel for HID interface are designed for human-machine interactive scenarios to realize the audio control of the device;finally,the DMA channel is designed to use the ping-pong transmission method and its Pa RAM parameters are configured for data replication between the memory and the register,and at the same time,the cache is used and the cache consistency is maintained to meet the real-time requirements of data processing.Finally,the USB sound card module designed realized the audio transmission and control functions,and these functions were tested separately.3.Design and implementation of equalizer algorithm.In order to further improve the quality of the audio stream,the graphic equalizer of octave distribution is designed by the combination of the shelving filter and the peak filter,and the limiter is designed for the scene of high-level signals to prevent signal distortion.By connecting the algorithm interface of the equalizer with the audio control interface of USB,the ten-segment graphic equalizer control is realized.Finally,the designed equalizer was tested in a specific scene,the results show that the equalizer can effectively improve the sound quality and enhance the personalized listening experience.