USB interfacing with 16 bit microcontroller

[FvM]

It's rather annoying that you didn't read the Microchip documents that have been suggested in the previous posts.

Running USB in high speed mode from internal clock isn't possible according to datasheet, probably not accurate enough. You can use an external 8 MHz crystal (also 4, 8, 12, 16, 20, 24, 40, 48 MHz).

 

[c_mitra]

I know it is messy but it is also interesting. The documentation is very well written but you need to read them perhaps more than once (it is your first time, I guess).