Re: [Discuss-gnuradio] Using USRP from multiple applications simultaneously

[Harald Welte]

On Sun, May 01, 2005 at 02:17:29PM -0700, Eric Blossom wrote:

> The Tx and Rx sides are completely independent and we often run
> different apps for Tx and Rx simultaneously.  The Tx and Rx paths have
> different USB endpoints for their streaming data.  This is what allows
> different apps/processes to open them.  They share a common control
> endpoint (EP0), but that can be opened by more than one processes
> since only usb command packets are used.

I seem to be unable to run usrp_siggen and usrp_fft simultaneously.  I
will try to investigate what exactly the issue is, and get back to you.

> It would be possible with a bit of hacking to run endpoints 2, 4, 6
> and 8 "double buffered", 2 512 byte buffers each.  That would give us
> 4 bulk endpoints to work with (and would also lower the worst case
> latency).

that would allow us to have two bulk-in and two bulk-out, each belonging
to one of the daughterboards.  Only complex samples of the same
channel would be multiplexed within one endpoint.  Sounds good.

> > Seperating it into four interfaces (2rx, 2tx) might be complicated,
> > since there certainly are shared data structures and functional blocks.
> 
> Mostly the complication comes in the FPGA.  [...]

Thanks for your elaboration on that.  This was what I actually feared.
Especially since I've noticed that you're already running out of cells
on the FPGA...

-- 
- Harald Welte <address@hidden>                         http://gnumonks.org/
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