USB UART Interface on Silicon/FPGA
And one part is to have a USB port interfaced using UART.


This is, frankly, a highly questionable design. USB does not map well onto an asynchronous serial stream, and most UARTs will have difficulty running at a speed suitable for even USB 1.1 (12 Mbit/sec). More importantly, using a UART here does not solve any real design problem; the complexity of a USB controller does not lie in its interface with the host processor.


  I have been looking into some semiconductor IP cores that I can use to interface USB using UART and I've found this project to be useful.


That project does not implement any aspect of USB. (The name is incorrect.) It's simply a UART, and not even a particularly good one -- the author's notes indicate that they were unable to get it to work reliably above 115.2 kBaud. It cannot be used to interface with a USB device.