I am a college student experimenting with VHDL and currently using the Spartan 3 starter kit. This particular kit (unlike the Spartan3e) does not come with an onboard usb connector. I was hoping to add one and bring in the D+ and D- lines directly into the FPGA I/O pins. I realize that these signals are RS485 differential, and that the FPGA would require LVTTL input.
I plan to hook a device like a usb mouse to this board, which would only use USB1.1 standard, and I expect the swing to be somewhere around3.3 to 3.6V, and the the tolerance would be safe enough to bring into the FPGA. Is this something that can be done? I am still fumbling around the thick USB manual, but I believe that it is possible.
Assuming that I am stuck with the current Spartan3 board, how can I allow a low speed device like a mouse to interface with the FPGA? Thank you very much for any insight you can offer.