Re: [Discuss-gnuradio] GRC - wrapping a GNU Radio block that uses message_sink

[Josh Blum]

A message sink takes a gr_stream in, and outputs a message. Vice-versa 
for message source block.

In grc, set the block wrapper port (source or sink) to type "msg". When 
you connect two blocks with type "msg". GRC creates a message queue 
called $(sink_block_id)_msgq_out and $(source_block_id)_msgq_in. The 
blocks using the message queue should expect a variable of this name to 
exist and can pass the message queue as an argument to the hier block or 
message block constructor.

See the grc/blocks/gr_message_source(sink) blocks as examples.

-Josh

On 02/21/2010 02:58 PM, Richard Clarke wrote:
> Hi,
>
> I have a 3rd party GNU Radio block of signal processing code that I would
> like to wrap for use within GRC. This block uses a message sink (i.e a
> pointer to a gnu radio message queue is passed into the block which appears
> to then utilise the queue for inserting 'send frequency correction' values
> to another process. I have read that GRC currently supports users creating
> block wrappers for blocks with message queue IO. In the xml file I write, is
> the message queue a second 'sink', i.e in addition to the standard float
> stream of samples it outputs, or should it be handled in the parameter
> section of the xml code? I've searched all existing standard blocks and
> haven't found an example to work from. Does anyone have an example they
> could share?
>
> Or have I also got my source and sink perspectives confused and this block
> should instead be a msg source? Even so, my questions above remain.
>
> Many thanks.
>
> Cheers
> Richard
>
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio