Re: [Discuss-gnuradio] Writing a block in Python (+XML)

[Marcus Müller]

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Hi Tom,

> Have been trying to write a block in Python.  Did not use the
> modtool.py, since my understanding is it may not yet support that.
Luckily, you're wrong.
gr_modtool -l python add
works like a charm.

> The block has only one output, no inputs. Also wrote the
> corresponding XML file. the block shows up correctly in GRC when I
> select it and add it to the flowgraph.
It's a source :)
> I've defined the output signature in the work function ( 1, 1,
> gr.sizeof_float). My work function writes to output_items[0][ some
> indexes] and returns with a count of  the number of written output
> items.
very well :)

> Initially I derived the block from gr.block, but it complained
> about no connection to the output, so I changed it to derive from
> gr.hier_block2. When running the flowgraph with my block in it,
> gnuradio complains that there is no output connection inside my
> block.
Oh, that's wrong. A hier_block is a hierarchical block, that is, only
a set of connections between other blocks and maybe some logic.
You can't have "work" in a hier_block; well, you can, but it won't be
called by the GNU Radio scheduler.

> 
> Any advice?
A hier block can't be used here. I don't know about your flowgraph,
but: did you really connect your gr.block-subclass' output to let's
say a null sink or a vector sink?


My advice is: Use gr_modtool, it really makes life easier and failsafer.

Greetings,
Marcus

> 
> -- Tom, N5EG
> 
> 
> 
> _______________________________________________ Discuss-gnuradio
> mailing list address@hidden 
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
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