On 11/17/2014 08:46 PM, George Sklivanitis wrote:
Hi all,

I think what Lefteris tries to implement is a 2x2 loopback with a USRP-B210.

At least this is what I can see from the flowgraph attached in the first email.
Is that possible with B210?

Best,
George
Yes, that should easily be possible.

But some checking code was added in UHD 3.8.0 which apparently gets inappropriately triggered sometimes, which is what is causing this
  issue.

There was also talk about running and executing the entire flow-graph at a cadence of faster than 1Hz, which suggested some design issues
  in the intended application not related to the bug in UHD.



On Mon, Nov 17, 2014 at 5:47 PM, Ben Hilburn <b...@ettus.com <mailto:b...@ettus.com>> wrote:

    Hi Lefteris -

    We recently added that warning. We think we got it right, but it's
    possible something is wrong with the logic that makes it fire.

    Can you share your GRC flowgraph?

    Cheers,
    Ben

    On Mon, Nov 17, 2014 at 2:28 PM, Marcus D. Leech
    <mle...@ripnet.com <mailto:mle...@ripnet.com>> wrote:

        On 11/17/2014 05:15 PM, Lefteris Kampianakis wrote:
        Hello,

        FYI I am having problems even with a simpler configuration
        like this:

        USRP_source_channel1 --> USRP_sink_channel1
        USRP_source_channel2 --> USRP_sink_channel2


        Does anyone face the same issue? It is really frustrating
        because 1/3 executions are wasted and this causes problems
        with later design, that has to have an execution rate of > 1Hz

        Thank you in advance
        Lefteris






        On Fri, Nov 14, 2014 at 6:32 PM, Lefteris Kampianakis
        <e.kampianakis...@ieee.org
        <mailto:e.kampianakis...@ieee.org>> wrote:

            Hello,

            I have a B210 and I am trying to transmit and receive
            from all it's channels simultaneously. My setup is a
            macmini late 2012 with Ubuntu 12.04 install. I compiled
            and installed gnuradio from source using the gnuradio
            build script. I have developed the attached very simple
            GRC script that looks like this

            signal_source@1khz --> USRP_sink_channel1
            signal_source@2khz --> USRP_sink_channel2

            USRP_source_channel1 --> WX_GUI_scope_channel1
            USRP_source_channel2 --> WX_GUI_scope_channel2

            The problem I have is that I get the following message at
            random times and on average on 1/3 executions of the GRC
            script.

            linux; GNU C++ version 4.6.3; Boost_104800;
            UHD_003.008.000-18-g864f84b5

            Using Volk machine: avx_64_mmx_orc
            -- Operating over USB 3.
            -- Initialize CODEC control...
            -- Initialize Radio control...
            -- Performing register loopback test... pass
            -- Performing register loopback test... pass
            -- Performing CODEC loopback test... pass
            -- Performing CODEC loopback test... pass
            -- Asking for clock rate 32.000000 MHz
            -- Actually got clock rate 32.000000 MHz
            -- Performing timer loopback test... pass
            -- Performing timer loopback test... pass
            -- Asking for clock rate 28.000000 MHz
            -- Actually got clock rate 28.000000 MHz
            -- Performing timer loopback test... pass
            -- Performing timer loopback test... pass
            -- Tune Request: 915.000000 MHz
            --   The RF LO does not support the requested frequency:
            --     Requested LO Frequency: 915.000000 MHz
            --     RF LO Result: 914.999999 MHz
            --   Attempted to use the DSP to reach the requested
            frequency:
            --     Desired DSP Frequency: -0.000001 MHz
            --     DSP Result: -0.000001 MHz
            --   Successfully tuned to 915.000000 MHz
-- -- Tune Request: 915.000000 MHz
            --   The RF LO does not support the requested frequency:
            --     Requested LO Frequency: 915.000000 MHz
            --     RF LO Result: 914.999999 MHz
            --   Attempted to use the DSP to reach the requested
            frequency:
            --     Desired DSP Frequency: -0.000001 MHz
            --     DSP Result: -0.000001 MHz
            --   Successfully tuned to 915.000000 MHz
-- -- Asking for clock rate 28.000000 MHz
            -- Actually got clock rate 28.000000 MHz
            -- Performing timer loopback test... pass
            -- Performing timer loopback test... pass
            -- Tune Request: 915.000000 MHz
            --   The RF LO does not support the requested frequency:
            --     Requested LO Frequency: 915.000000 MHz
            --     RF LO Result: 914.999999 MHz
            --   Attempted to use the DSP to reach the requested
            frequency:
            --     Desired DSP Frequency: 0.000001 MHz
            --     DSP Result: 0.000001 MHz
            --   Successfully tuned to 915.000000 MHz
-- -- Tune Request: 915.000000 MHz
            --   The RF LO does not support the requested frequency:
            --     Requested LO Frequency: 915.000000 MHz
            --     RF LO Result: 914.999999 MHz
            --   Attempted to use the DSP to reach the requested
            frequency:
            --     Desired DSP Frequency: 0.000001 MHz
            --     DSP Result: 0.000001 MHz
            --   Successfully tuned to 915.000000 MHz
-- *thread[thread-per-block[2]: <block gr uhd usrp sink
            (24)>]: RuntimeError: b200: 2 RX 1 TX and 1 RX 2 TX
            configurations not possible*


            It is obvious that I have all channels activated and that
            this message shouldn't be appearing in the first place,
            let alone, appearing in a non-deterministic manner.

            Any ideas?

            Thank you in advance
            Lefteris




-- Eleftherios(Lefteris) Kampianakis
        Electronics and Computer Engineer
        PHD Candidate and Researcher at Sensing Computing
        Communications Group (SGCC)
        Department of Electrical Engineering
        University of Washington
        3927 Adams Lane, NE, Mercer Court D805B, 98105
        website: http://staff.washington.edu/ekampian/
        <http://users.isc.tuc.gr/%7Eekabianakis/>
        mail: e.kampianakis...@ieee.org
        <mailto:e.kampianakis...@ieee.org>


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        We shall probably need a more-detailed description of what
        you're doing.  Like the actual .grc files, etc.

        From your description, I think you're wanting to:

        bring up flow-graph, exchange a very small number of samples,
        and then exit the flow-graph, and do this in a loop?

        That seems horribly inefficient, quit distinct from it perhaps
        uncovering possible bugs in the latest UHD.

        But providing more information will help those who can help you.


-- Marcus Leech
        Principal Investigator
        Shirleys Bay Radio Astronomy Consortium
        http://www.sbrac.org


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--
Sklivanitis Georgios
Postgraduate Student
Telecommunications Division
Technical University of Crete
ECE Dept.
Tel. : 28210 59257

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