Have you verified timestamps are disabled? And have you issued a stream
command to the RX as well as set_rx_streamer()? To be clear, I haven't
tried E310 loopback with any UHD version later than the date of the article
(4/22/17), but I don't believe significant changes have happened which
would affect loopback since then (maybe someone from Ettus could chime in).

I don't think you'll be able to run at full DSP clock rate -- set the
device to stream at (say) 10Msps on RX and TX first and then increase it
from there.

send() and recv() are strictly functions to submit and receive data from
the ARM (PS)  to the FPGA (PL) and vice versa. They are not necessary for
loopback.

Nick

On Fri, Feb 23, 2018 at 10:26 AM Adam Kurisko <adamk...@outlook.com> wrote:

> Hey Nick,
>
>
> Thanks for the quick reply.
>
>
> I have already disabled time stamping and initiated the streamers and it
> compiles and runs on my board, however when I run it the LEDs on the RX2
> and TRX frontend do not light up, so I am lead to believe that it
> actually might not be streaming.
>
>
>  Just for clarification, Do the 'uhd::tx_streamer::send()' and
> 'uhd::rx_streamer::recv()' functions route the signal to buffers on the
> ARM host or the fpga? I ask that because those functions seem to be the
> only way that I can get those LEDs on the frontend to light up signifying
> that the device is actually streaming.
>
>
> Thanks,
>
> Adam
> ------------------------------
> *From:* Nick Foster <bistrom...@gmail.com>
> *Sent:* Friday, February 23, 2018 1:01:42 PM
> *To:* Adam Kurisko
> *Cc:* usrp-users@lists.ettus.com
> *Subject:* Re: [USRP-users] [E310 RFNoC] TX RX Loopback bypassing the ARM
> processor
>
> 1. yes
> 2. RFNoC
>
> I refer back to a post I wrote detailing loopback in the FPGA. It doesn't
> work "out of the box" but can be made to with minor modification.
>
> https://corvid.io/2017/04/22/stupid-rfnoc-tricks-loopback/
>
> If you haven't used RFNoC before you should probably take on the Getting
> Started guide first:
> https://kb.ettus.com/Getting_Started_with_RFNoC_Development
>
> Nick
>
> On Fri, Feb 23, 2018 at 9:28 AM Adam Kurisko via USRP-users <
> usrp-users@lists.ettus.com> wrote:
>
> Hello all,
>
>
> I am trying to utilize the full performance of the E310 and it seems like
> the Arm processor is the bottleneck in this scenario. I know the AD9361 is
> wired straight into the fpga, so it would make sense that a strictly bare
> metal loopback is possible.
>
>
> Is it possible to stream data straight from RX to TX without sending or
> receiving from the host ARM processor? And if so, how would I do this?
>
>
> Please let me know.
>
>
> Thank you,
>
> Adam
> _______________________________________________
> USRP-users mailing list
> USRP-users@lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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