I don’t see that connection at schematic.
I suppose square pad 1 is at schematic on the left and is connected to pad 2 of transformer so why you think of connecting it to pad 1.
I don’t see that connection at schematic.
The schematic has the terminal numbers from the original component, the pcb layout has its terminal numbers from editing them inline with my actual components. I have looked to see if I could re-number the schematic without success, could this be one of my problems?
I once more don’t understand what “editing inline with components” means.
What you are doing (and why) after updating pcb according to schematic?
Perhaps I don’t know something but I never had any need to edit any pin numbers at PCB. Having right pin numbers is the task for symbols and footprints before schematic and pcb are started to be designed.
Simplifying the process after updating pcb from schematic I only move footprints to right positions and make connections using tracks.
Sorry I’m not clear.
Using the transformer as an example.
I chose the nearest component I could find in the library and placed it in the Schematic.
I then edited its footprint so it matched my actual component. Number of pins and their numbers.
That footprint was then used on the PCB.
I hope that makes sense.
Yes, it makes sense, but if you did it as you described then at PCB you will have the same pin numbers as at the schematic, but you don’t have. Don’t you see it?
I don’t think you have right pin numbers at schematic and right pin numbers in footprint?
If so then tell me why you have at schematic connector pin 1 connected to transformer pin 2 but you are asking about connecting that pin 1 to transformer pin 1 and it looks you don’t see any problem in asking such question.
How does KiCad know which symbol pin represents which pad of the footprint? may be good to read.
Thanks for your help.
I am afraid that now you are not clear !
So the footprint was numbered like the actual component, the schematic still has its original, incorrect numbers.
I think I do that is why I asked this:
It is working backwards to the schematic from the footprint that seems to be my problem.
But then again there is also the question of ‘nets’… but one step at a time.
Here is what I don’t understand.
KiCad uses pin numbers from schematic and looks for the same pin number in footprint. So if your symbol at schematic is connected with your footprint then connections made on PCB are based on that numbers - they just can’t be different at schematic and at PCB as it is the way to establish which pin is connected with which.
Thanks eelik, I have quickly read it and it confirms I have ‘crossed’ pin/pad numbers.
Fixing it is my problem
The concept of a net is very fundamental in KiCad (and any other PCB design software)
A net is basically everything connected by copper, and a list of them is called a netlist.
It is possible to generate a netlist as a separate file, but these day’s the netlist is communicated directly between Eeschema and Pcbnew.
So for a pad and track to be connected they must be in the same net?
But could be on a different Net to the other side of a component.
Simple example Pad > Track > Pad > Resistor > Pad > Track
Have I got that right?
Again, to make it as simple as possible (simplifying a bit):
- Everything (each symbol pin / footprint pad) which must be connected together must belong to the same net.
- Each pin or pad can belong only to one net.
- In the schematic, symbol pins are connected with wires (or labels).
- In the layout, footprint pads are connected with tracks, vias and zones (i.e. copper).
This required a second reading, but if I understood you correctly, you understood correctly.
A “net” is an abstract entity, and the netlist itself is generated in the schematic, and it does not have necesarrily to do with physical copper in PCBnew.
From the example screenshot eelik posted:
Net 1: R1 pad 1 and R2 pad2 are connected.
Net 2: R2 pad1, R3 pad 1 and R4 pad 2 are connected.
This netlist is already made in the schematic by drawing the wires between the schematic components. For most components the pin numbers are visible, but resistors are one of the few components for which pin numbers do not add mostly clutter in the schematic, and they are therefore hidden (but they still exist).
The netlist can be made visible by printing it to a file. In KiCad V5 this can be done with: Eeschema / Tools / Generate Netlist File….
OK, thanks understood. Your schematic explained it better than my words.
Paul. I see the nets are also available in Pcbnew under, Inspect > List nets, my list as below.
So my remaining problem is to get my trafo schematic connection numbers to match the footprint.
I will try again to edit a standard component and see if I can accomplish it.
I don’t know about your specific “trafo”, but in general…
If there’s a datasheet for the component and it has pin numbers and pad numbers, you should follow them. It’s possible to get a symbol/footprint combination working in KiCad but if they conflict external information sources you may run into problems. You may need to adjust the symbol, the footprint or both. In any case I recommend copying both to a personal library as a “fully defined” component: the symbol in the library has the footprint field populated with the correct footprint.
After the schematic was saved was the net imported to pcbnew?
Or are you just copying the schematic visually?
Just asking because you say you are newby.
Unfortunately not and that I think that was my problem. I wasn’t aware how strictly the schematic was followed in the footprint and then onto the pcb. I have gone back to the transformer library and found a better match. That wasn’t easy as I had to go through every model that looked like it had the correct spec, my exact model was not listed.
I have now imported that and started to make track connections, fingers crossed.
Yes it was. One of the things I did correctly!
Making some progress but need some more advice please.
The two small downward facing vertical tracks need to terminate in Pads.
to enable me to wire the piggyback board in position.
I can’t find single pads to add.
I have tried to copy and paste ones from the trafo secondary but nothing pasted?
Pads are only found in footprints.
So if you want pads, make a footprint first.
…And that footprint must come from a library, and also be linked in from the schematic to add it to the netlist.
Thanks understood but I have gone through the footprint library and couldn’t find anything that I thought would be right. Do you have a suggestion please?