Re: [Discuss-gnuradio] [SOCIS '17] GRC C++ Output: Week 8

[Marcus Müller]

Hi Federico,

so your idea is to use GNU Radio Companion to design blocks that internally has a loopback?

That would kind of break the semantics of GRC being a tool for designing GNU Raio flow graphs, but I'd still be open to that idea, if you could explain in which way that would differ from it simply being a unified "control loop" block that only is parameterizable (in which case you wouldn't benefit from the graphical representation of it being multiple blocks with feedback, because it's not what's happening, more confusing than clarifying).

So, I don't really think that we can find a sufficiently general approach here that would justify letting users do something that GNU Radio itself can't. I'd much rather fix the scheduler than spend time on emulating a fix by having restricted feedback ability that only allows a very limited set of blocks to work in the feedback branch.

What do you think?

Best regards,

Marcus

On 09/19/2017 08:29 AM, Federico 'Larroca' La Rocca wrote:

Hi Marcus, 

Me and my team would be glad to help. I am aware that block interconnection depends on the scheduler, which forbids loops. However, my idea was not as ambitious as modifying the whole scheduler, but customizing the companion to generate the c++ code of a block, and thus my question (a sort of hier block, in terms of the companion, but written directly on c++, without interconnecting blocks, i.e. it would automatically generate the work() function, etc.). 

This would of course be much less powerful than allowing loops on a flowgraph, and only certain operations would be allowed (those for which a c++ function exists). But it would allow to program relatively simple but useful blocks, including loops, with all the simplicity of the companion. 

What do you think? 

best

Federico

2017-09-18 19:52 GMT-03:00 Marcus Müller <address@hidden>:

Hi Federico,

Loops in the Flowgraph are currently forbidden by GNU Radio itself, not by the GRC designer.

So, no, this is not scope of Hakon's project. If you want to contribute to having that feature in a generally useful manner, we can certainly chat about how you can improve the scheduler to make that possible.

Best regards,

Marcus

On 09/18/2017 03:44 PM, Federico 'Larroca' La Rocca wrote:

Hi,

Outputting c++ from the companion would be a great addition to GNU Radio. A small question: the possibility of having loops on the flowgraph is contemplated on this project? We've been using GNU Radio for teaching for some years now (highschool, undergraduate and graduate students), and such feature would be very useful and illustrative. For instance, when using a PLL, we have to resort to feedforward schemes or using the blocks already part of GNU Radio, but as a black box of sorts. Coding in c++ would be asking too much from students in a course where the focus is on communications, whereas the companion is simply perfect in terms of intuitiveness and ease of use.

best

Federico

2017-09-18 6:10 GMT-03:00 Håkon Vågsether <address@hidden>:

Hi all,

The focus for this week has been the QT blocks. You can read more at:

https://grccpp.wordpress.com

Best regards,

Håkon Vågsether

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