Is there an easy way to reuse a part of a project’s schematic and corresponding PCB layout?
For example I wanted to reuse an LDO section of a previous board to a new project. I copied the schematic section and the PCB section to the new project. I made the references match between them (e.g. R17) but after I updated the PCB from the Schematic all the components got a copy of it, so I had to delete the copied ones and replace them with the ones added from the Schematic.
At least I didn’t have to reroute and add copper zones to the LDO section.
Take a look to Kicads hierarchical schematics. Draw your LDO circuit into a seperate file and put hierarchical labels to the input and output. Make a root sheet and Place-AddSheet. You may link to the LDO part on the other sheet now. You even can use this several times inside the same design if you need several diffrent voltages. Kicad creates a instance of the source sheet automatically.
Its like software writing when you copy any code part into another single one by including it. Switching to hierarchical design, you may compare with compile what has a linker and you are able to call a library function with parameter passing on stack. You may call this function several times and Kicad always annotates correct reference designators for the complete design automatically.
I have done the same copy/paste with bits of schematic and pcb into a new project. Manually ensuring that the reference designators match is important – there is some sort of “paste-special” mode where it keeps the ref-des when you paste, but I am travelling and can’t check that right now. If you don’t paste-special you can just manually change the ref-des to match. Of course, you need to not have duplicate ref-des so also ensure that your new pasted ref-des stuff does not conflict with other stuff you have already drawn. It sounds like you got this far though.
The trick, when you update-pcb-from-schematic, is to check the box that says “re-link-footprints-using-ref-des” (or something to that effect). The normal mode is to update using the internal unique id numbers. After you do your special ref-des update, uncheck that box for normal workflow.
