Hey Jason, Yes 512 is the max SPP, due to the 4k max DMA transfer size. To support larger FFTs, you could modify the FFT noc block to split up the frames between multiple packets and issue an EOB on the last packet. I have tried that in the past and had some success.
Jonathon On Tue, Sep 25, 2018 at 8:54 PM Jason Matusiak via USRP-users < usrp-users@lists.ettus.com> wrote: > Is the max usable SPP size on the E310 capped at 512? In my flowgraph, I > have an RFNoC FFT block. I know that the SPP needs to be set to the size > of the FFT to make things happy and using 512 seems to work fine. As soon > as I step up to 1024 I see a lot of errors: > > > RFNoC Streamer block received error ERROR_CODE_BAD_PACKET (Code: 0xf) > [ERROR] [STREAMER] The receive packet handler caught a value exception. > ValueError: Bad CHDR or packet fragment > [ERROR] [STREAMER] The receive packet handler caught a value exception. > ValueError: Bad CHDR or packet fragment > RFNoC Streamer block received error ERROR_CODE_BAD_PACKET (Code: 0xf) > timeout on chan 0 > timeout on chan 0 > RFNoC Streamer block received error ERROR_CODE_BAD_PACKET (Code: 0xf) > [ERROR] [STREAMER] The receive packet handler caught a value exception. > ValueError: Bad CHDR or packet fragment > [ERROR] [STREAMER] The receive packet handler caught a value exception. > ValueError: Bad CHDR or packet fragment > > (over and over) > > I know that when using an X310 it is sometimes necessary to increase the > MTU size when you want to be able to have larger SPPs, but the E310 doesn't > use an ethernet interface, so I don't know if there is an analogous > approach that can be taken here (and reading this comment from a few years > back supports my thought, at least as of 2015: > http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-December/017356.html). > I also tried a flowgraph with just a radio and a keep-1-in-N and I still > get the same errors with an SPP=1024, so it isn't the FFT causing the > issues. > > So is SPP=512 the max usable value and is there anything I can do to > increase it so I can use a larger FFT size on the E310? > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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