Re: [Discuss-gnuradio] New block: Segfault thrown when calling self.connect

On 09/27/2011 06:09 PM, Sebastian Götte wrote:
> Hello,
> I wrote a GNU Radio block using the template from here:
> http://gnuradio.org/redmine/projects/gnuradio/wiki/Basic_block
> which shall eventually become a source module providing access to a
> low-speed electroencephalographic capture board I designed and built, in
> order to "abuse" the GNU Radio framework for that kind of data analysis.
> This is the test program I tried to run (generated with grc, modified by
> hand):
> https://github.com/jaseg/openmind-viewer/blob/master/apps/top_block.py
> On each run the program throws a segfault in the second connect call on
> line 55:
> self.connect((self.openmind_buspirate_source_0, 0),
> (self.gr_interleaved_short_to_complex_0, 0))
> When I follow the segfault using gdb or pdb I end up somewhere in the
> gnuradio internals.
> I have no idea what causes this segfault and would be glad for any hints.
> The source files of the rest of the block are to be found here (I do not
> know which are actually relevant to this question):
> https://github.com/jaseg/openmind-viewer
> Thanks in advance (hoping that I provided enough information)
>
Without looking too deeply into it, having looked-over your block
source, I might suggest that a better approach to interfacing to
your "buspirate" device would be to write an external program and
have it communicate data over a named pipe, and your Gnu Radio
"stuff" can simply use a 'file source' on the named-pipe. There's no
real performance penalty for this--named pipes are quite fast, and
your source looks like it runs at a paltry 115200Kbps, which is "way
down in the noise" as far as sample rates go.

My suspicion is that there's something wrong with your I/O signatures
which is causing the Gnu Radio flow-graph "organizer" to
barf in a non-graceful way.

--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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