this is my first PCB I want to create. It is a devel board with a MOLEX socket and pin header and test points.
I downloaded the MOLEX socket description from their website.
When switching into the PCB editor and updating the PCB from the schematic I see warnings like:
Warning: No net found for component J3 pad 27 (no pin 27 in symbol).
Warning: No net found for component J3 pad 28 (no pin 28 in symbol).
Error: J3 pad 13a not found in Connector_PinHeader_2.54mm:PinHeader_2x20_P2.54mm_Vertical.
Error: J3 pad 13b not found in Connector_PinHeader_2.54mm:PinHeader_2x20_P2.54mm_Vertical.
These are 40 warnings and errors corresponding account to my 2x20 pin header.
And the pins are not connected a I would expect.
My guess was that kicad could not automatically assign the MOLEX pins to the pin header because I chose “row name before number”. I changed it to “number before row” with the same result.
KiCad is very straightforward in matching the pins on the schematic symbols with the pads on the PCB footprints. It uses the pin numbers, and the pin numbers only. But the pin “numbers” can have letters to. Some other programs use some sort of translation table, but KiCad does not do that.
Now ready your warning message again:
Apparently, there is a pad with pad number 27 in the PCB footprint, but that number does not exist in the schematic symbol, because all pins of J3 end with either an a or a b.
For the rest:
The symbols for J1 and J2 are definitely not from KiCad’s standard library. Why did you put in those symbols? The usual workflow in KiCad is to use the standard symbols, and then just assign any of the many possible footprints to them. This is the advantage of KiCad’s straigthforward 1:1 mapping of pins to pads.
For the pin header I use one of the standard footprints:
Connector_PinHeader_2.54mm:PinHeader_2x20_P2.54mm_Vertical
For the MOLEX I use the footprint that they provide.
When I open the property window of the MOLEX footprint I don’t see a pin numbering.
The numbering is greyed out, so it is disabled and can not be edited.
Please post a screenshot of your layout.
One thing to be aware of - your J3 shows pin names of 1a / 1b … 20a / 20b.
If your footprint doesn’t use that naming convention, you will get these errors. You may need to edit your footprint or schematic symbol to match each other.
Yes, J1 and J2 are from MOLEX. I thought reusing symbols would be efficient.
Now replaced them with symbol (Conn_01x20) and footprint (Connector_PinHeader_1.00mm:PinHeader_2x10_P1.00mm_Vertical_SMD) from the standard library.
The message is the same.
From what you are saying I have to somehow rename the pins 21 … 40 of J3 so that when switching to the PCB editor they can be matched to J2 pins 1… 20. How would I do that?
However, I don’t see rubber bands from J1 pins 1 … 20 to J3 pins 1a … 20a either. I might need to rename them, too. Correct?
It looks for me that whenever someone uses symbols or footprints found somewhere he loses much more time than if he used KiCad library symbols and footprints or even design his own symbols and footprints.
At least for the first few times.
Once you understand KiCad conventions and common caveats, custom symbols and footprints are as easy as default ones.
My main issue with default footprints is real world availability.
“Oh this seems to be a common part. Let’s use it” -later that day- “What? End of life? No 1:1 replacement available on mouser? - Back to the drawing board”
