How can I create a Hierarchical block with GNURadio Companion?

Question

I am trying to create a Hierarchical block using the GNURadio Companion GUI. Answers I've found in other posts say to select the blocks you want to incorporate, then go to More -> Create Hier. Then a new screen is supposed to appear. However, doing "Create Hier" with any combinations of blocks selected seems to do nothing.

Am I doing something wrong, or is there a problem with my GRC?

Answer 1

It's very simple. You just start with a new flow graph in GRC, and use Pad Sources as input, and Pad Sinks as output.

If you want to let the user configure something, use a Parameter GRC block.

You must set the Generate Options in the Options block to Hier Block, and set a sensible ID there, too – don't stick with top_block, but use something (without spaces or -; it needs to work as a python name) that won't conflict with something else.

Here's an example:

You can then Generate button (or press [F5]), and then, after you've done a rescan of your block library with the refresh button you can find (and use) your new block in the Block Category you specified.