# External Clock in GRC **URL:** \ **Category:** GNU Radio\ **Created:** [May 25, 2010, 2:49pm UTC](https://www.ruby-forum.com/t/external-clock-in-grc/189145 "2010-05-25T14:49:51Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Damien\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ee59a6/32.png) [@Damien\_S](https://www.ruby-forum.com/u/Damien_S)\ **Post date:** [May 25, 2010, 2:49pm UTC](https://www.ruby-forum.com/t/external-clock-in-grc/189145/1 "2010-05-25T14:49:51Z")
Hello, I’m trying to use the external clock input of the USRP2. Since i’m using GRC, i tried to modify the xml usrp2\_source block (the usrp2\_source\_xxxx.xml file) to add this feature. This is what I did: I added a \<-PARAM\> section: \<-param\> Clock type clk\_type enum Internal internal fcn:usrp2.MC\_WE\_DONT\_LOCK External external fcn:usrp2.MC\_WE\_LOCK\_TO\_SMA \<-/param\> And i added this command in the section: self.$(id).config\_mimo($clk\_type.fcn) Can you tell me if there is a chance for this to work ? And if i am using the good command to use the external clock (i read that it was also possible to modify the firware to use the external clock) ? ## Thanks in advance. Damien S. View this message in context: [http://old.nabble.com/External-Clock-in-GRC-tp28667726p28667726.html](http://old.nabble.com/External-Clock-in-GRC-tp28667726p28667726.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Damien\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ee59a6/32.png) [@Damien\_S](https://www.ruby-forum.com/u/Damien_S)\ **Post date:** [May 25, 2010, 5:16pm UTC](https://www.ruby-forum.com/t/external-clock-in-grc/189145/2 "2010-05-25T17:16:50Z")
Damien, I use: Clock Source usrp2\_clock\_src usrp2.MC\_WE\_DONT\_LOCK enum Internal usrp2.MC\_WE\_DONT\_LOCK External SMA usrp2.MC\_WE\_LOCK\_TO\_SMA External MIMO usrp2.MC\_WE\_LOCK\_TO\_MIMO and : self.$(id).config\_mimo($usrp2\_clock\_src) It works for me. To be complete it should probably have an option for MC\_PROVIDE\_CLK\_TO\_MIMO, but I don’t use it so wasn’t motivated enough. I thought this was going to be pushed into the repo master branch. _shrug_ –Eric ---
**Author:** ![Damien\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ee59a6/32.png) [@Damien\_S](https://www.ruby-forum.com/u/Damien_S)\ **Post date:** [May 25, 2010, 5:43pm UTC](https://www.ruby-forum.com/t/external-clock-in-grc/189145/3 "2010-05-25T17:43:46Z")
On Tue, May 25, 2010 at 08:10, Eric S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I thought this was going to be pushed into the repo master branch. > _shrug_ Hmm, perhaps this slipped through the cracks. It’s a good idea. Was there a patch posted? Johnathan ---
**Author:** ![Damien\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ee59a6/32.png) [@Damien\_S](https://www.ruby-forum.com/u/Damien_S)\ **Post date:** [May 26, 2010, 11:49pm UTC](https://www.ruby-forum.com/t/external-clock-in-grc/189145/4 "2010-05-26T23:49:42Z")
Johnathan C.-2 wrote: > Johnathan > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](http://lists.gnu.org/mailman/listinfo/discuss-gnuradio) Not by me. Indeed i’m a noob in Linux and in Gnuradio so i simply don’t know how to do that. Perhaps Eric is more qualified to do that ? – View this message in context: [http://old.nabble.com/External-Clock-in-GRC-tp28667726p28686557.html](http://old.nabble.com/External-Clock-in-GRC-tp28667726p28686557.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).