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Re: [Discuss-gnuradio] Embedded control of USRP

From: Eric Blossom
Subject: Re: [Discuss-gnuradio] Embedded control of USRP
Date: Thu, 20 Apr 2006 13:07:24 -0700
User-agent: Mutt/1.5.9i

On Thu, Apr 20, 2006 at 01:38:52PM -0500, Jim Hanlon wrote:

> I tried to get the USRP talking to an 800MHz VIA fanless industrial
> control computer, with expansion card to get USB 2.0 performance. I
> found that gnuradio installed and ran OK, but USRP performance
> consistently exhibited USB overruns and underruns, to the point that
> our evaluation of USRP capabilities was limited by our compute
> power.

> I think its nice to be fanless, if you can. And maybe, some clever
> engineering of USB interrupt service routines could improve i/o
> performance. But it is much simpler these days just to outrun the
> problem with a faster CPU clock.

> If you are trapped by form factor and "no fan" rules, you may be out
> of luck. Does your architecture allow for (say, USB) expansion cards
> ?  If so, you could build one that did block transfers to/from the
> USB bus and your slowish CPU.

> Jim Hanlon

As always, there are lot of differences between processors.  Some of
the VIA's are dogs, other's aren't so bad.  We've run the USRP and
gmsk2 code on one particular compact VIA board, and it wasn't horrible.
We were able to run GMSK at a few 100 kb/sec with it.

The USB expansion card could have been the problem.  How do you know
it was lack of CPU?


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