Re: [Discuss-gnuradio] Problem with 3.3.0 howto-write-a-block

[Martin Braun]

On Thu, Mar 24, 2011 at 05:21:11PM +0800, honglonglong wrote:
> Hi all,
> I am new to gnuradio and studying the "How to write a block" article
> written by Eric Blossom in 2004. However, I am using the latest version
> 3.3.0 of the source code of howto-write-a-block and find differences in
> codes and article.
> 
> When the article says the qa_howto.py would fail for no module named
> howto, my version of qa_howto.py runs correctly.
> 
> I find instead of importing howto module, the 3.3.0 version imports
> howto_swig. Is this the cause of the problem? Is the article still valid
> for 3.3.0 version?

Hi honglonglong,

quite a bit has changed from when that article was written. Most
concepts are still valid (e.g. QA test code, and the idea of sync-blocks),
but a lot of the details have changed.

First of all, remember that gr-howto-write-a-block is more than just an
example, you can use it as a template for writing your own out-of-tree
modules. So you can immediately start writing code and using it with
your GNU Radio installation. So perhaps it isn't really necessary to
understand all of the details.

I recommend startіng like this:
- Create your own module using the create-gnuradio-out-of-tree-project
  command. This will rename the module from 'howto' to something else.
- Give it a try, compile the entire thing and run the qa code.
- Add a block of your own. You can use gr_modtool.py from
  https://www.cgran.org/wiki/devtools, which automatically updates your
  Makefiles and creates skeleton code for a new block.
  If you're completely new to all of this, start with a sync_block. This
  means you produce as many output items as you have input items.
- Write some QA code, then write some signal processing code. Start with
  something simple.
- This seems weird, but don't install anything (run 'sudo make install')
  until you're absolutely sure your stuff is correct.

Once you've got that working, the rest will follow quite easily.

Cheers
MB

-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
Research Associate

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Building 05.01
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Phone: +49 721 608-43790
Fax: +49 721 608-46071
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KIT -- University of the State of Baden-Württemberg and
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