Re: [Discuss-gnuradio] How to write USB 2.0 interface for Windows in C++?

[Eric Blossom]

On Tue, Feb 03, 2009 at 10:53:01AM +0500, Ujala Qasim wrote:
> I actually want to interface the USRP and a DSP board together. For this I
> need to write the USB 2.0 interface between them. I am initially trying to
> write a C++ code that will capture the data samples from USRP's USB 2.0 in
> Windows. Later, I will try to use the same code on DSP board.

OK

> What information should I know before writing this interface?

You should have a good understanding of USB 2.0 and in particular the
concepts of endpoints and types of transfers (we primarily use bulk
transfers).  The USB 2.0 spec is available on line.

Our abstract interface to the USB primitives is contained in
fusb.{h,cc}.  fusb_generic.{h,cc} provides a concrete generic
interface that works, but is likely to be slow.  In order to change
the least amount of code, create new concrete classes derived from
those in fusb.h, then create appropriate fusb_sysconfig_* files to
link it in.  See fusb_*.{h,cc} for OS specific implementations.

> Also, from where I can get to know about the architecture and
> working of FPGA on the USRP?

This diagram is pretty good:
  http://gnuradio.org/trac/wiki/UsrpRfxDiagrams

The USRP FAQ is good:
  http://gnuradio.org/trac/wiki/UsrpFAQ

And of course, you've got the FPGA code available to you:
  usrp/fpga/toplevel/usrp_std/usrp_std.v


Eric