Re: (gnuradio3.8) module 'gnuradio.blocks' has no attribute 'message_sink'

[Criss Swaim]

Here is a solution using an asynchronous probe:

In this application, there is a need to periodically send signals to a background task for non-realtime calculations.

>             # connect the
>           queue to the input signal
>                       msgq = gr.msg_queue(2)
>                       msg_sink =
>           blocks.message_sink(gr.sizeof_float*num_bins, msgq, True)  #
>           dont block
>                       self.connect(self, msg_sink)
>           
>                       # start the update thread
>                       update_thread(
>                           num_bins=num_bins,
>                           update_timeout=update_timeout,
>                           msgq=msgq,
>                         ........
>                        )
      then in the background thread, the queue is read
        and processed

>             # read from
>           the queue and resize to have arrays of size num bins
>                       raw_samps =
>           numpy.fromstring(self._msgq.delete_head().to_string(),
>           numpy.float32)
>                       raw_samps.resize(len(raw_samps) / self._num_bins,
>           self._num_bins)

With the message_sink block no longer supported, the probe_signal_vf  block works for me:

>             # setup the
>           probe and connect to input signal
>                      probe = blocks.probe_signal_vf(num_bins)
>                      self.connect(self, probe)
>           
>                       # start the update thread
>                       update_thread(
>                           num_bins=num_bins,
>                           update_timeout=update_timeout,
>                           probe = probe,
>                           ......
>                       )  
>         
      and in the background thread:

>            # read from the
>           probe and resize to have arrays of size num bins
>                       raw_samps = numpy.array(self._probe.level())
>                       raw_samps.resize(1, self._num_bins)
      This will work if your application does not need
        every signal passed to the background task.

Criss Swaim
cswaim@tpginc.net
cell: 505.301.5701

On 1/15/2021 2:09 AM, Marcus Müller wrote:

> So, the old msg_queue infrastructure of GNU Radio has been removed, yes.
>
> A suitable replacement are the asynchronous message passing blocks.
> Depending on your use case, the conversion of your code should be
> relatively straightforward - the message debug sink might even do what
> you want.
>
> Best regards,
> Marcus
>
> On 07.01.21 04:46, Ting Wu wrote:
> > Hi!
> >
> > I recently upgraded to gnuradio 3.8 and my old code threw the following
> > error:
> >
> > module 'gnuradio.blocks' has no attribute 'message_sink'
> >
> > Is the 'message_sink' has been deprecated in the recent version of
> > gnuradio? If so, what should I use now for the message source and sink?
> > I really do not want to rewrite all the codes, so I would be really
> > grateful if there is a simple way to make the following code work with
> > the recent version of gnuradio. The code simply gets data stream from a
> > USRP N200 (LFRX daughterboard).
> >
> > =================================================
> >  class my_block(gr.top_block):
> >     def __init__(self):
> >         gr.top_block.__init__(self)
> >         self.source = uhd.usrp_source(device_addr="",
> > stream_args=uhd.stream_args('sc16', 'sc16', args="scalar=1024"))
> >
> >         self.source.set_samp_rate(samp_rate)
> >         self.source.set_gain(gain)
> >         self.source.set_center_freq(0)
> >
> >         self.queue = gr.msg_queue()
> >         self.sink = blocks.message_sink(gr.sizeof_short*2, self.queue,
> > False)  #This line throws the error
> >         self.connect(self.source, self.sink)
> > ===================================================
> >
> > Thanks in advance!
> >
> > Ting Wu
> >
> >
> >       
>