New symbols for 7400 library


ok, thanks for the clarification. To dwell on the subject, here another issue:
The file bel_test.lib contains a single component with a dedicated text “OR” for unit D. It applies for this unit exclusively. Later in schematic the text “OR” does not appear unit D. What is wrong ?
bel_test.lib (863 Bytes)


The usual reason for mismatch between library and schematic is that the cache has got out of sync, or there are more than one library with the same component name. Restarting KiCad usually fixes cache issues, unless there is something in project-cache.lib, in which case deleting (or renaming just in case) that file helps.


As @bobc said, there could be a symbol name conflict. In kicad a symbol name needs to be unique over all loaded libraries. (otherwise the symbol from the lib with the highest priority is taken.)
More details:


When adding the unit I see the text “OR” in the preview. So there seems the correct library selected. Just try with the library file I have provided and see …


Nope, the preview knows what the library is, but the schematic does not, it uses the first one in the library list, so it depends on search order. It is probably finding the standard 74xx.lib before yours. This is very easy to verify.

  1. In eeschema, right click over component, then select Edit Component->Edit (or E key)
  2. Click “Test” button. This tells you which library eeschema is actually using.


I inserted his lib at the top and i get the OR text in the last gate.

@MarioBlunk An or gate has a different gate shape. I would advice you really change the outline to be correct. (or use the IEC symbols if you want text)
From wikipedia:


Hi there,
I got the point that KiCad takes the component from the topmost library in the library list. The “test” button shows me that indeed the component has been taken from the wrong library (at least not the one I want).

  1. But why does it offer me to select the component from the lower priority library and even offer a preview ?
  2. Is there a way to force eeschema to take the particular component from a lower priority library ? (The “select” button does not do the job, by the way.)

edit: I’m aware of logic symbols. The “OR” text is just part of evaluating and playing.


This is because of the way the library system and the file format are structured. As @bobc explained the dialog for adding a symbol has the information about which library is open. There is no place in the eeschema file format to store this information. This means once you add the symbol into the schematic this information does no longer exist.
Yes there should at least be an error message.

The future file format will (hopefully) contain the information from which lib a symbol came from. But i fear we will need to wait until v6. (I think it is not part of v5. But i could be wrong here.)

I don’t think so. you can move the lib in question up. (or simply rename the symbol.)


I had to share my last project with the guy that created the circuit. (Fortunately he finally capitulated and gave up on Eagle after the last license change.) To do that I moved the project specific cache library up to the top of the list. That allowed me to make sure he had the symbols I used and I knew which ones I was working from. Any changes are for that project only. That can be good or bad. Not much of an issue to alter the library, save, and then change to another library and save again though.


30 posts were split to a new topic: Coloured fill in logic symbols

Coloured fill in logic symbols
Coloured fill in logic symbols

I used a polyline, but I generate it within the script, it’s too hard to draw by hand… KiCad automatically close the polygon to fill, so you can have the outline open. I had to adjust the other arcs so that they do not spill out of the outline.


Split out the colour fill chatter. This topic is about the 7400 symbols, hidden power pins and errors in the old symbols