How to implement message passing in GNU Radio?

Question

I need to implement message passing, my idea is to make some sort of message source (I inherit from public gr_sync_block ) that works as a controller for another block (it has to send a message each 6 minutes).

I read that is necessary to inherit from gnuradio::block -and by the way, installing grextras is mandatory-. In the .h file I added the #include <gnuradio/block.h> and inherited from block class JDFM_API jdfm_control : public gr_sync_block, public gnuradio::block . I know that I have redefine some things like the gnuradio::block constructor but I dont know what msg_signature is, I also don't get the relation between block's parameters and work parameter, the last thing that I am not sure is if I still can use gnuradio-companion if I create a block like this.

I haven't been able to find a simple example of messages implementation. If anyone can guide me or show me an example, it would be awesome.

Thanks in advance.

Answer 1

This has already been done, by Josh Blum, and is available as part of his GNURadio extras packages on GitHub:

https://github.com/guruofquality/grextras/wiki#wiki-feature-message-passing

Enjoy!