An FPGA-based USB full-speed device core to implement USB-serial, USB-camera, USB-audio, USB-disk, USB-keyboard, etc. It requires only 3 FPGA common IOs rather than additional chips. 基于FPGA的USB full-speed device端控制器，可实现USB串口、USB摄像头、USB音频、U盘、USB键盘等设备，只需要3个FPGA普通IO，而不需要额外的接口芯片。
