Re: [Discuss-gnuradio] GRC GUI parameters for custom blocks

[Cristian Rodríguez]

Hi Vipin.

2017-07-02 23:12 GMT-05:00 Vipin Sharma <address@hidden>:

Thanks Cristian. 

I understand the runtime part. What if I don’t want the parameters to change during runtime. I just want to do some initial initialization through GUI for some parameters.

 

The GUI is launched just when the simulation has started, so if you want to change from GUI it is already runtime.

 

Do I still need the callback?

Yes, you will need.
 

Also, it will be helpful if you could point me to some documentation which explains all the guts of GRC framework. The tutorial on gnu radio wiki aren’t that very advanced.

I learned a lot of these pages, about creating the blocks:

https://wiki.gnuradio.org/index.php/Guided_Tutorial_GNU_Radio_in_Python
https://wiki.gnuradio.org/index.php/Guided_Tutorial_GNU_Radio_in_C%2B%2B

About the buffers on GNURadio, Marcus made a very useful entry:

https://www.gnuradio.org/blog/buffers/

About the PMT Types, you can read the reference page and these other pages:

https://gnuradio.org/doc/doxygen/namespacepmt.html#a7ab95721db5cbda1852f13a92eee5362

https://gnuradio.org/doc/doxygen/page_pmt.html
https://wiki.gnuradio.org/index.php/Guided_Tutorial_Programming_Topics#5.3.2_Adding_Message_Passing_to_the_Code

In general I have been a bit of time with GNURadio, but the best way to learn is to read the codes of the blocks. It apply specially in the callbacks.

Best regards,

Cristian

 

Vipin

On Jul 2, 2017, at 1:42 AM, Cristian Rodríguez <address@hiddencom> wrote:

On Jul 1, 2017 2:18 PM, "Vipin Sharma" <address@hidden> wrote:

Hi,

I have a custom block, say CustomBlock, which takes two arguments, arg0 and arg1. My intention is to have these arguments be configured through gui after the custom block is instantiated. I define <param> entries for these arguments in the xml file for the CustomBlock which allows GRC gui to let me configure the arguments interactively.

Hi Vipin.

I had a similar question, and Bastian answered as follows:

If you want to change the parameter while the flow graph is running (through a slider in the GUI, for example), you will have to extend the block with a callback.
You could have a look at the Frame Equalizer block, for example. It allows changing the algorithm during run-time.

To extend the block you have to:
- add the callback function to the XML description of the block:  (see here https://github.com/bastibl/gr-ieee802-11/blob/next/grc/ieee802_11_frame_equalizer.xml#L9)
- implement the callback for the block (note that the callback is a public function that has also to be added to the definition in /include/, and the use of a mutex since ‘work’ and the callback are called in different thread contexts).

I am trying to understand the relation ship between GRC GUI custom block parameters and the CustomBlock C code’s function arguments. How does GRC framework pass GUI parameters to its associated C function which also has the same arguments?

As Bastian said, you can't modify the parameters from the GUI if they don't have a callback function.

Best regards,

Cristian

Vipin
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