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Source code


Name: softusb
Created: Aug 5, 2010
Updated: Apr 19, 2013
SVN Updated: Aug 24, 2010

Other project properties

Category: Communication controller
Language: Verilog
Development status: Alpha
Additional info: Specification done
WishBone Compliant: Yes
License: GPL


SoftUSB is part of the Milkymist System-on-Chip , the most advanced open source SoC for interactive multimedia applications.

  • Supports full (12Mbps) and low (1.5Mbps) speed operation
  • Two downstream ports with shared bandwidth
  • Integrated PHY
  • Directly interfaces to common USB transceivers such as the MIC2550A
  • Hybrid architecture featuring the Navré AVR compatible processor (8-bit RISC) to implement the complex parts of OHCI in C software.
  • Two asynchronous clock domains: system clock and 48MHz USB
  • AVR program and OHCI descriptors and data are stored in shared (system addressable) on-chip dual-port RAM

SoftUSB is work in progress, for the latest information or to contribute to the development please see the Milkymist-devel mailing list and the #milkymist channel on the Freenode IRC network. In particular, testers are wanted for the Navré softcore.

More information

  • CSR bus specifications