On Fri, Aug 9, 2013 at 1:02 PM, Martin Lülf <m...@mluelf.de> wrote: > Hi, > > since I also had trouble with this issue at first, please allow me to > clarify this further: GNURadio does not support looping of blocks. Inside a > single block you can loop as often as you wish and that is exactly how the > available PLLs in GNURadio are made. Just search the mailing list for more > details, since this topic has been discussed a couple of times already. > > Yours > Martin > > > > Am 09.08.2013 17:17, schrieb Martin Braun (CEL): >> >> On Fri, Aug 09, 2013 at 07:31:58AM -0700, tom sutherland wrote: >>> >>> I am trying to make a simple PLL using a VCO but I get an error >>> "RuntimeError:flow graph has loops!". Anyway around that? >> >> >> Nope, stock GNU Radio does not support loops. There's plenty of PLLs >> available already, though. >> >> MB
Yes. From a scheduler standpoint, loops, as in traditional control loops with some required and guaranteed delay, are incredibly inefficient. And instead of figuring out how to support something like that, Eric made the decision very early on to just not allow them at all. You can use the asynchronous message passing interface to do loops. However, it's asynchronous, so you're not going to be building a PLL or something like that which mathematically falls apart if you have more than 1 sample delay in it. But you can at least use it to feed back data/metadata/control info if you don't need that kind of requirement. But if you do, follow Martin and Martin's advice and do it inside of a block. -- Tom Visit us at GRCon13 Oct. 1 - 4 http://www.trondeau.com/grcon13 _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
