# Passing messages to block values?

**URL:** <https://www.ruby-forum.com/t/passing-messages-to-block-values/230831>\
**Category:** GNU Radio\
**Created:** [July 8, 2014, 4:48am UTC](https://www.ruby-forum.com/t/passing-messages-to-block-values/230831 "2014-07-08T04:48:08Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [July 8, 2014, 4:48am UTC](https://www.ruby-forum.com/t/passing-messages-to-block-values/230831/1 "2014-07-08T04:48:08Z")

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GR 3.7.4 now has a message output on the QT GUI Frequency Sink. Is  
there way  
in GRC to pass this message to a value field within a block? For  
instance,  
pass it to the Center Frequency value in the UHD Source block to retune  
the  
hardware?

Is there a way to disable the frequency re-centering when the mouse is  
clicked, that way I could pass the frequency to a channelizer without  
altering the main spectral display.

Thanks,  
Lou  
KD4HSO

–  
View this message in context:  
[http://gnuradio.4.n7.nabble.com/Passing-messages-to-block-values-tp49240.html](http://gnuradio.4.n7.nabble.com/Passing-messages-to-block-values-tp49240.html)  
Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![madengr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ec9cab/32.png) [@madengr](https://www.ruby-forum.com/u/madengr)\
**Post date:** [July 8, 2014, 12:05pm UTC](https://www.ruby-forum.com/t/passing-messages-to-block-values/230831/2 "2014-07-08T12:05:18Z")

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On 07/08/2014 04:46 AM, madengr wrote:

> GR 3.7.4 now has a message output on the QT GUI Frequency Sink. Is there way  
> in GRC to pass this message to a value field within a block? For instance,  
> pass it to the Center Frequency value in the UHD Source block to retune the  
> hardware?

Hey Lou,

not yet, but very soon it will 🙂

> Is there a way to disable the frequency re-centering when the mouse is  
> clicked, that way I could pass the frequency to a channelizer without  
> altering the main spectral display.

Tom fixed that very recently. If you git pull the latest master, it  
won’t do that.

M

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**Author:** ![madengr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ec9cab/32.png) [@madengr](https://www.ruby-forum.com/u/madengr)\
**Post date:** [July 8, 2014, 2:37pm UTC](https://www.ruby-forum.com/t/passing-messages-to-block-values/230831/3 "2014-07-08T14:37:55Z")

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Martin,

After git pull, do I have to remove the build directory and rebuild the  
entire code, or can I do a:

sudo make uninstall  
cmake ../  
make  
make test  
sudo make install

to just recompile the changed files. As a general rule, say going from  
3.7.3 to 3.7.4, it’s unclear to me when I should rebuild everything.

Thanks,

Lou  
KD4HSO

Martin B.-2 wrote

> Tom fixed that very recently. If you git pull the latest master, it  
> won’t do that.

–  
View this message in context:  
[http://gnuradio.4.n7.nabble.com/Passing-messages-to-block-values-tp49240p49243.html](http://gnuradio.4.n7.nabble.com/Passing-messages-to-block-values-tp49240p49243.html)  
Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![madengr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ec9cab/32.png) [@madengr](https://www.ruby-forum.com/u/madengr)\
**Post date:** [July 8, 2014, 4:54pm UTC](https://www.ruby-forum.com/t/passing-messages-to-block-values/230831/4 "2014-07-08T16:54:28Z")

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On Tue, Jul 8, 2014 at 8:36 AM, madengr [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> to just recompile the changed files. As a general rule, say going from  
> 3.7.3 to 3.7.4, it’s unclear to me when I should rebuild everything.
> 
> Thanks,
> 
> Lou  
> KD4HSO

Nope, no need to uninstall and clean things like that. Generally, within  
the same version, you can just rebuild and install. It’s between  
versions  
that you’d want to uninstall, clean up your build directory, and  
rebuild.  
But for a small change like this after updating from git, save yourself  
a  
lot of time and just call make:

$ git pull  
$ (change to build directory)  
$ make -jN (for N cores on your machine)  
$ make test (optional)  
$ sudo make install

Then you should be all set. If there were any changes made to  
cmakefiles,  
make will know that and rerun cmake for you.

Unfortunately, this time, it won’t save you a lot of time since we did  
some  
white space cleanup on the tree, so we touched a lot of files…

Tom