Very simple USB 1.1 PHY. Includes all the goodies: serial/parallel conversion, bit stuffing/unstuffing, NRZI encoding decoding. Uses a simplified UTMI interface. Currently doesn t do any error checking in the RX section [should probably check f

UTMI全称为 USB2.0 Transceiver Macrocell Interface，此协议是针对USB2.0的信号特点进行定义的，分为8位或16位数据接口。目的是为了减少开发商的工作量，缩短产品的设计周期，降低风险。此接口模块主要是处理物理底层的USB协议及信号，可与SIE整合设计成一专用ASIC芯片，也可独立作为PHY的收发器芯片，下以8位接口为例介绍PHY的工作原理及设计特点。 -UTMI called USB2.0 Transceiver Macrocell Interfac

usb serial core is a vhdl synthesizable code, implementing serial data transfer over usb. Combine with a UTMI-compatible transceiver chip, this core acts as a USB device that transfers a byte stream in both directions over the bus