Nitro USB core

This fpga core implements a USB Full-Speed SIU using only normal FPGA CMOS IOs.

The main design goals are:

• Small and efficient (originaly targetting ice40)
• Flexible, even at runtime (dynamic EP config)
• Constant size no matter how many EPs are use
• Single clock-domain (currently 48M but soon extended to any 12M multiple starting at 36M).

Limitations

The current code in this repo targets the iCE40 only and uses some direct SB_IO and SB_RAM_4K instances. A more generic version will be added soon, it has already been run on ECP5 for the Hack-a-day badge 2019 supercon but the small tweaks haven't been added here yet.

License

See LICENSE.md for the licenses of the various components in this repository