On 10/30/2018 10:42 AM, Daniel May via USRP-users wrote:
Is there a way to query the amount of data in the FIFO so that I can wait until it clears?
I don't believe so.

You could simply wait an amount of time, based on empirical data, that is commensurate with your sample rate.

But the whole "the next run causes fatal errors" thing does need to be investigated, I agree.



On Tue, Oct 30, 2018 at 9:37 AM Rob Kossler <rkoss...@nd.edu <mailto:rkoss...@nd.edu>> wrote:

    The DRAM is 2GB, I think.

    On Tue, Oct 30, 2018 at 10:34 AM Daniel May <danielma...@gmail.com
    <mailto:danielma...@gmail.com>> wrote:

        Thanks, I'll give that a try. I thought it might be the FIFO
        clearing, but it takes longer than I would expect. There's
        only 512kB of FIFO, correct? It takes up to several seconds to
        finish at a 1 Msps rate.

        Restarting the radio before Tx completes causes the radio to
        enter an unrecoverable error state. This is a UHD or Firmware
        bug, correct?

        Thanks,
        Daniel

        On Tue, Oct 30, 2018 at 9:12 AM Rob Kossler <rkoss...@nd.edu
        <mailto:rkoss...@nd.edu>> wrote:

            It sounds like the DMA FIFO is just emptying out.  For
            fast sample rates, the FIFO empties quickly, but for slow
            sample rates, it empties slowly.  Perhaps you could supply
            the arg "skip_dram=1" so that the streaming goes directly
            to the DUC rather than through the FIFO.  This will
            probably work fine for slow sample rates (i.e., perhaps a
            FIFO is not needed for such rates).
            Rob

            On Mon, Oct 29, 2018 at 4:17 PM Daniel May via USRP-users
            <usrp-users@lists.ettus.com
            <mailto:usrp-users@lists.ettus.com>> wrote:

                All,

                Can anyone else reproduce this issue and/or suggest a
                solution?

                This is happening over the Ethernet interface as well.
                Application exits, Tx light stays on, relaunching
                application causes X310 to enter an unrecoverable
                state and requires power cycling. It looks like an
                issue with initializing DMA. Tested using v3.13.0.1.

                Thanks,
                Daniel

                On Wed, Oct 10, 2018 at 10:55 AM Andrew Toomey via
                USRP-users <usrp-users@lists.ettus.com
                <mailto:usrp-users@lists.ettus.com>> wrote:

                    All,

                    I am using an Ettus x310 over PCIe and am noticing
                    that there is a delay from when my program
                    finished sending to the radio and when the radio
                    tells me that transmission as ended ( the red Tx
                    light turning off).

                    As I bump up the sample rate I notice this delay
                    decreases until it is nonexistent. Is this
                    intended behavior or have I done something wrong
                    in my tests? The procedure to test this is listed
                    below:

                    1.Download a copy of the official UHD example
                    scripts from
                    
https://github.com/EttusResearch/uhd/tree/master/host/examples

                    2.Ensure that UHD is installed correctly on your
                    testing device and build the example programs above

                    3.Run the following command “ ./tx_waveforms -
                    -rate=1000000 - -freq=1500000000

                    4.Stop the program at any time (how long the radio
                    is running does not affect the delay)

                    5.Observe the radio and notice that the red light
                    under the Tx/Rx port is still lit on the RF A channel

                    6.If you start another transmission while the
                    light is still red, the console output contains
                    hundreds of thousands of L’s and the radio will
                    not receive data until the USRP object is recreated.

                    I am also curious if there is a hard stop
                    functionality for this radio. All the examples I
                    have seen send an End of Burst packet but is there
                    a way to completely halt the radio without doing this?

                    Thanks for the help!

                    Andrew

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