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Re: [Discuss-gnuradio] USRP2 spontaneously dies while transmitting

From: Eric Blossom
Subject: Re: [Discuss-gnuradio] USRP2 spontaneously dies while transmitting
Date: Tue, 4 Aug 2009 15:05:17 -0700
User-agent: Mutt/1.5.18 (2008-05-17)

On Tue, Aug 04, 2009 at 05:55:27PM -0400, Andrew Lutomirski wrote:
> On Tue, Aug 4, 2009 at 5:52 PM, Eric Blossom<address@hidden> wrote:
> > On Tue, Aug 04, 2009 at 04:38:56PM -0400, Andrew Lutomirski wrote:
> >> Hi all-
> >>
> > First off, I highly suggest that you add yourself to group usrp if
> > you're not already, then add this line to /etc/security/limits.conf:
> >
> > address@hidden  - rtprio 50
> Already tried that and it didn't help.
> I'm using an Intel 82566DC-2 (e1000e) attached to a switch, which is a
> terrible idea, but I don't really mind occasional flakiness.
> My main objection is that I have to reboot the USRP2 when it dies.
> I'd expect it to recover.
> Also, tx_samples often freaks out and saturates the network, even at
> interpolation 20.  IMO that shouldn't happen no matter what happens to
> priorities, the link, the network card, or the USRP.

You're running it through a switch.  We tell you not to do that.
Your switch is probably declining to be flow controlled by the USRP2,
hence there's no back pressure being applied to the host, thus the
unbounded amount of data sent from the host.

Rule 1: Don't connect your USRP2 via a switch

Rule 2: If you think you know what you're doing and understand the ins
        and outs of ethernet PAUSE frames and asymmetric flow control,
        and can get your switch to accept flow control from the USRP,
        then it _may_ be possible to make it work through a switch.

Rule 3: See Rule 1.

> > Do you have the TTL serial port on the USRP2 connected?  If so, what
> > was the last thing it said?
> Nope.  I might try that eventually, but I probably won't get a chance
> for a week or two.


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