Usb Soundcard Design

This paper demonstrates how to design and implement an USB sound card. This article is based on the specification and definitions of the USB audio device, and showed the topography and circuit block diagram of the USB sound card. According to diagrams, the circuit has been determined. Finally, based on the specification of USB audio card and the USB audio class, part of the software has been completed.The design of the hardware circuit is implemented by the I2C interface, microprocessor (MCU) CY7C67300 which has the external RAM expansion interface, the programmable gate array (FPGA) FLEX10K and PCM audio codec chip UDA1342. CY7C67300 takes the responsibility of communicating with USB host which included responding to the request of the host, reporting device descriptor, transmitting audio data stream, etc. FLEX10K processed the audio signal and the control signal of the host. UDA1342, which has an internal 16-bit ADC and DAC, takes the part of transferring the digital audio data to the analog signal for the speaker and converted the analog signal to digital code for the host. And it comes with mute and volume control which receiving the control data from the FPGA. This design enables the whole function of data transmission by the USB bus. Because of an external USB audio card and 16-bit codec processing which avoid the interference of the internal noise, The sound is much more perfect than the internal audio card. In additional, it is implemented the volume control and mute function through two external buttons.The design can use a powerful MCU and Audio Code IC without FPGA to implement, but here the FPGA is considered to achieve more function to reduce the effect of MCU in terms of verifying the stability and reliability of the hardware design and the circuit structure which can be referred to complete the single chip circuit designo...