Hierarchical sheets, duplicate component numbers


I’m busy with a project taking a old paper schematic and entering it in KiCad. I have started to use hierarchical sheets which are working well.

In the schematic there is a RF modulator section (Which I’ve added to a hierarchical sheet) which was designed by another company, so it has some of the same component references used in the main schematic, so like C1 is used in the main schematic and in the RF Modulator.

When I run a ERC check its then complaining about duplicate numbers. Is there a way around this apart from giving the component a unique reference.

Maybe something like in hierarchical sheet, the component can be referred to C1.hierarchical-sheet-name?


If you have 99 or less components per sheet, you can multiply the sheet number by 100 and add that to the existing reference designator number. So, if the RF sheet is sheet number 3 then C1 will become C301. Yes, this will break some continuity with the copied design, but think about how easy it will be to find the right sheet when trouble shooting why C301 is messing things up. The reference designator now tells you what sheet number to look on to find the component, and hopefully the surrounding circuit.

(This sheet number * 100 is one of the auto annotation options. That is where I got this idea from. If there are more than 99 components there is an option for sheet number * 1000.)


Thanks, great idea. Will go with that.