# Calling usrp\_source block function from other block **URL:** \ **Category:** GNU Radio\ **Created:** [February 17, 2015, 5:53pm UTC](https://www.ruby-forum.com/t/calling-usrp-source-block-function-from-other-block/234229 "2015-02-17T17:53:58Z")\ **Posts on this page:** 3\ **Page:** 1
**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:** [February 17, 2015, 5:53pm UTC](https://www.ruby-forum.com/t/calling-usrp-source-block-function-from-other-block/234229/1 "2015-02-17T17:53:58Z")
Hi all, I’m looking for the best way to retune the USRP from another block in a running flowgraph. I’ve seen the tune callback method used by bin\_statistics\_f, but I was wondering if there are other ways to do it. I took a look at message passing ([http://gnuradio.org/doc/doxygen/page\_msg\_passing.html](http://gnuradio.org/doc/doxygen/page_msg_passing.html)), but I’m not sure how to bind usrp\_source’s set\_center\_freq to handle a freq passed by message, etc. Are there any examples of doing this laying around or is bin\_statistics\_f’s tune callback still the best way to do it? -Doug ---
**Author:** ![AndersonS\_Douglas\_J](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@AndersonS\_Douglas\_J](https://www.ruby-forum.com/u/AndersonS_Douglas_J)\ **Post date:** [February 17, 2015, 9:48pm UTC](https://www.ruby-forum.com/t/calling-usrp-source-block-function-from-other-block/234229/2 "2015-02-17T21:48:46Z")
On Tue, Feb 17, 2015 at 11:52 AM, Anderson, Douglas J. \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: > Are there any examples of doing this laying around or is > bin\_statistics\_f’s tune callback still the best way to do it? > > -Doug Hi Doug, Take a look at the UHD page: > **[GNU Radio Manual and C++ API Reference: UHD Interface](https://www.gnuradio.org/doc/doxygen/page_uhd.html)** The existing command message interface to the UHD block’s already allows you to set the frequency with a message. This manual page will tell you how to format that message properly. Tom ---
**Author:** ![AndersonS\_Douglas\_J](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@AndersonS\_Douglas\_J](https://www.ruby-forum.com/u/AndersonS_Douglas_J)\ **Post date:** [February 18, 2015, 5:33pm UTC](https://www.ruby-forum.com/t/calling-usrp-source-block-function-from-other-block/234229/3 "2015-02-18T17:33:22Z")
Thanks Tom, that gives me a good starting point. -Doug * * * From: removed\_email\_address@domain.invalid [removed\_email\_address@domain.invalid] on behalf of Tom Rondeau [removed\_email\_address@domain.invalid] Sent: Tuesday, February 17, 2015 1:47 PM To: Anderson, Douglas J. Cc: GNURadio D.ion List Subject: Re: [Discuss-gnuradio] Calling usrp\_source block function from other block On Tue, Feb 17, 2015 at 11:52 AM, Anderson, Douglas J. \ wrote: Hi all, I’m looking for the best way to retune the USRP from another block in a running flowgraph. I’ve seen the tune callback method used by bin\_statistics\_f, but I was wondering if there are other ways to do it. I took a look at message passing ([http://gnuradio.org/doc/doxygen/page\_msg\_passing.html](http://gnuradio.org/doc/doxygen/page_msg_passing.html)), but I’m not sure how to bind usrp\_source’s set\_center\_freq to handle a freq passed by message, etc. Are there any examples of doing this laying around or is bin\_statistics\_f’s tune callback still the best way to do it? -Doug Hi Doug, Take a look at the UHD page: [http://gnuradio.org/doc/doxygen/page\_uhd.html](http://gnuradio.org/doc/doxygen/page_uhd.html) The existing command message interface to the UHD block’s already allows you to set the frequency with a message. This manual page will tell you how to format that message properly. Tom