[Discuss-gnuradio] problem with custom RFNoC block output in GRC

[Jason Matusiak]

I am having some issues with a custom RFNoC block output when trying to
run my python script.  My block takes in a complex int 16, and outputs a
complex int 16 as well as a "byte".  The byte is really a 32b value that
the receiving end will use to convert to a float.  This is a follow on
from a previous GRC conversation I had here [1].

Right now I am testing my pass-through of the complex data (to get my
axi flags working right), so I don't even care about the byte data, but
it is what is giving me issues...

So based on the previous thread, I have an RFNoC GRC block that has an
output of a "byte", but I am attempting to put 32b through it.  I've
tried passing that through a RFNoC: FIFO to a File Sink, as well as just
going from the block to a Null Sink, neither are working.  When I got
straight to a Null Sink, I get the following:
Traceback (most recent call last):
  File "time_sync.py", line 160, in <module>
    main()
  File "time_sync.py", line 148, in main
    tb = top_block_cls()
  File "time_sync.py", line 117, in __init__
    self.connect((self.uhd_rfnoc_streamer_time_sync_0, 1),
(self.blocks_null_sink_0, 0))    
  File
"/home/jason/target/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 47, in wrapped
    func(self, src, src_port, dst, dst_port)
  File
"/home/jason/target/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 110, in connect
    self.primitive_connect(*args)
  File
"/home/jason/target/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py",
line 4569, in primitive_connect
    return _runtime_swig.top_block_sptr_primitive_connect(self, *args)
ValueError: itemsize mismatch: uhd_rfnoc_TimeSync0:1 using 8,
null_sink0:0 using 1
Segmentation fault (core dumped)


OK, makes sense, it says that I have 8B coming out of the TimeSync0:1,
but the null is expecting 1.  So I go into the python script and change
the following line:
self.blocks_null_sink_0 = blocks.null_sink(gr.sizeof_char*1)
to:
self.blocks_null_sink_0 = blocks.null_sink(gr.sizeof_char*8)

and now I get the output:
Traceback (most recent call last):
  File "time_sync.py", line 160, in <module>
    main()
  File "time_sync.py", line 149, in main
    tb.start()
  File
"/home/jason/target/lib/python2.7/dist-packages/gnuradio/gr/top_block.py",
line 109, in start
    top_block_start_unlocked(self._impl, max_noutput_items)
  File
"/home/jason/target/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py",
line 4876, in top_block_start_unlocked
    return _runtime_swig.top_block_start_unlocked(*args, **kwargs)
RuntimeError: uhd_rfnoc_TimeSync(1): missing connection from output port
0


This doesn't make sense to me as the following is in my pythonscript:
        self.blocks_null_sink_0 = blocks.null_sink(gr.sizeof_char*8)
        self.blocks_file_source_0_0 =
blocks.file_source(gr.sizeof_gr_complex*1,
"/home/jason/reducedInput.txt", False)
        self.blocks_file_sink_0 =
blocks.file_sink(gr.sizeof_gr_complex*1, "/tmp/complexData.txt", False)
        self.blocks_file_sink_0.set_unbuffered(False)

        ##################################################
        # Connections
        ##################################################
        self.connect((self.blocks_file_source_0_0, 0),
(self.uhd_rfnoc_streamer_fifo_0, 0))    
        self.connect((self.uhd_rfnoc_streamer_fifo_1, 0),
(self.blocks_file_sink_0, 0))    
        self.connect((self.uhd_rfnoc_streamer_time_sync_0, 1),
(self.blocks_null_sink_0, 0))    
       
self.device3.connect(self.uhd_rfnoc_streamer_fifo_0.get_block_id(), 0,
self.uhd_rfnoc_streamer_time_sync_0.get_block_id(), 0)    
       
self.device3.connect(self.uhd_rfnoc_streamer_time_sync_0.get_block_id(),
0, self.uhd_rfnoc_streamer_fifo_1.get_block_id(), 0)  


What am I missing here?  I assume I am doing something stupid somewhere
or am following Martin's plan for me in [1] incorrectly....

[1]
https://lists.gnu.org/archive/html/discuss-gnuradio/2015-12/msg00098.html