Yes, the spp needs to be the same. I don't use gnuradio much so I don't know if it may be manually configuring something, but in recent versions of UHD, the graph connection process will automatically try to set the SPP appropriately for all blocks using the "atomic item size" property of each block. In the case of the FFT block, this size is the FFT length I think and so other blocks would have to conform to that SPP.
On Tue, Sep 13, 2022 at 2:03 PM Paul Atreides <maud.dib1...@gmail.com> wrote: > If I recall correctly, the app has to be the same in all blocks when you > use the FFT, that’s the case for the Fosphor graph anyways. > Does that track with your understanding Rob? > > Get Outlook for iOS <https://aka.ms/o0ukef> > ------------------------------ > *From:* Rob Kossler <rkoss...@nd.edu> > *Sent:* Tuesday, September 13, 2022 9:54:02 AM > *To:* Minutolo, Lorenzo <minut...@caltech.edu> > *Cc:* USRP-users@lists.ettus.com <usrp-users@lists.ettus.com> > *Subject:* [USRP-users] Re: RFNOC4, FFT Block, Python > > Hi Lorenzo, > The FFT block requires the number of samples per packet to exactly equal > the FFT size. When the graph commits, UHD will try to resolve a packet > size that all of the blocks are happy with. Perhaps if the FFT size is > 2^11, this packet size may be bigger than the radio wants to deliver (or > bigger than the SPP you specified in the rx_streamer, I don't really know). > > In my opinion, this is a really unnecessary limitation of the stock FFT > block. With relatively minor changes, this block would not need any linkage > between packet size and FFT length. > Rob > > On Mon, Sep 12, 2022 at 8:20 PM Minutolo, Lorenzo <minut...@caltech.edu> > wrote: > > Hi All, > I'm using UHD 4.2 to play around with RFNOC4. I successfully added an FFT > block to the XG image of an X300, no static connections. uhd_usrp_probe > returns as expected. I use the attached code to test it out. > When I commit the graph I get the following error: > > Traceback (most recent call last): > File "/home/lorenzo/test_rfnoc_fft.py", line 71, in <module> > graph.commit() > RuntimeError: ValueError: samples per package must not be smaller than > atomic item size > > Digging a bit in the libraries I see that it originates from > rfnoc_streamer.cpp, specifically: > [...] > if (ais.is_valid()) { > const auto spp = > this->rx_streamer_impl::get_max_num_samps(); > if (spp < ais.get()) { > throw uhd::value_error("samples per package must not > be smaller than atomic item size"); > } > [...] > > Has someone encountered this error before? > > Thenks, > Lorenzo > > > > > > Attached code: > > args = "addr=192.168.30.2" > graph = uhd.rfnoc.RfnocGraph(args) > > radio_ID_A = uhd.rfnoc.BlockID(0, "Radio", 0); > radio_block_A = graph.get_block(radio_ID_A); > radio_ctrl_A = uhd.rfnoc.RadioControl(radio_block_A) > > set_freq = 300e6 > spp = 512 > radio_ctrl_A.set_tx_frequency(set_freq, 0) > tx_freq = radio_ctrl_A.get_tx_frequency(0) > radio_ctrl_A.set_rx_frequency(set_freq, 0) > rx_freq = radio_ctrl_A.get_rx_frequency(0) > print("Tuning is TX %.1f, RX: %.1f MHz" % (tx_freq/1e6,rx_freq/1e6 ) ) > > radio_ctrl_A.set_properties(f'spp={spp}', 0) > radio_ctrl_A.set_rx_antenna('RX2',0) > radio_ctrl_A.set_rate(200e6) > > > DDC_ID = graph.find_blocks("DDC")[0] > DDC_block = graph.get_block(DDC_ID) > DDC_control = uhd.rfnoc.DdcBlockControl(DDC_block) > DDC_control.set_input_rate(200e6, 0) > DDC_control.set_output_rate(5e6, 0) > > FFT_ID = graph.find_blocks("FFT")[0] > FFT_block = graph.get_block(FFT_ID) > FFT_control = uhd.rfnoc.FftBlockControl(FFT_block) > FFT_control.set_length(spp) > FFT_control.set_magnitude(uhd.libpyuhd.rfnoc.fft_magnitude.COMPLEX) > FFT_control.set_direction(uhd.libpyuhd.rfnoc.fft_direction.FORWARD) > FFT_control.set_shift_config(uhd.libpyuhd.rfnoc.fft_shift.REVERSE) > > stream_args = uhd.usrp.StreamArgs('fc32','sc16') > stream_args.args = 'spp='+str(spp) > rx_stream = graph.create_rx_streamer(1, stream_args) > > graph.connect( > radio_ID_A,0, > DDC_ID,0, > False > ) > graph.connect( > DDC_ID,0, > FFT_ID,0, > False > ) > > graph.connect( > FFT_ID,0, > rx_stream,0 > ) > > graph.commit() > > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > >
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