Why Are Parts Already Spread?


#1

KiCad 5.0.1 using Ubuntu 18.04.1 LTS OS. I got my Edge.Cuts layer rectangular board outline done correctly by using “Add graphic lines”. I imported the net list but all land patterns/footprints are not on top of each other as the documentation says. All the footprints are spread out with some being inside the board outline and some parts being outside the board outline at the upper right corner of the board. There are a few parts at the lower left hand side outside of the board outline. I don’t see the icon in the top row that your supposed to click on to spread the footprints (because they are already spread?). What is going on?
–Larry


#2

Docs are outdated. Yeah, they are already spread when you use the modern (default) canvas/toolkit, so you don’t need that functionality anymore - but in the future 5.1 there will be Place->Auto-place. IIRC it’s not there in 5.0. Why do you ask, is it only because the docs were confusing?


#3

I tend to read the manual/instructions on something new. Of course there are the philosophies of, “If everything else fails, then read the instruction manual” or “WARNING, Real Men don’t read the instructions”. I didn’t find the documentation confusing, I found the instructions incorrect and misleading.

Reminds me of the early 1980s when I was trying to analyze a waveguide bandpass filter with a microwave circuit analysis program called Super Compact. The instruction manual stated that if the source and load impedance were both the same (50 Ω) you only had to state it once. Problem was the programmers didn’t read the instruction manual and the program tried to divide by zero, thus gibberish or no output. The salesman said to state both the input and output Z and it would work. Thus this US $10,000 program needed a patch that turned into an update/revision.

The question now is, are some of the footprints inside of the board boundaries/layout the correct operation? I would think you would still want all footprints outside.
–Larry


#4

I agree, Larry.
The fact here is that the program is published before the whole documentation is updated. It is not bad, since we want new funcionalities as soon as possible.

Many people complaint about all the footprints were on a pile (or maybe a stack) and they wanted all the footprints spread out after netlist import.
It is fine for small boards. But when I come across a layout with hundreds of footprints I’d rather have the old feature. Then I choose when to spread out the footprints.

By the way, the spread-out-footprints-by-sheet feature is great.


#5

Well said :slight_smile: Unfortunately the volunteers (including me) haven’t been busy and the documentation isn’t in a good shape.

Do you mean you have drawn the Edge.cuts layer before you populate the file with footprints? We have different kinds of work flows, I have never designed the board outline beforehand. But anyways when you update the board for the first time you can move all the spread footprints outside the board immediately because they are selected and move with the mouse.

Alternatively you can select the Edge.Cuts layer, go to High contrast display mode, select the outline and move it farther. Then select and move the footprints, all or one by one. Then move the outline back to its place.


#6

eelik,
Yes, I did the Edge.Cuts layer board outline first. That’s because that is what the workflow of the instructions said to do. I had already placed some footprints and locked the two footprints that are for the mounting points. I figured I needed to move the footprints that were inside the board outline, so I enclosed all of the footprints in a box and moved them as a block to be outside the board outline. I didn’t want to fuss moving the board outline as I had it centered on the ANSI/ASME size A drawing sheet where I wanted it. All well and good but now all the footprints are locked because when I pick on a footprint, to move it, a box comes up saying so and I have to check the box that says to move anyway. I guess I need to draw a box around all these footprints and unlock them.
–Larry


#7

That’s right. I just don’t understand why they are locked, items are locked only by explicit action. Maybe you hit “toggle lock” hotkey by accident.

BTW, what document are you reading?


#8

Those steps could be performed in any order, depending on circumstances. On one extreme, you might do a complete layout, then the last step is to draw an outline around it and drop some mounting holes into place. (Then you throw a printout over the wall with the note, “You mechanical guys will just have to live with what we did over here in electrical design.”)

On the other extreme, before you even start the circuit design the mechanical guys tell you, “It’s gotta fit into this strange-shaped enclosure, and use the factory-provided mounting holes. Here’s the mechanical CAD file. Good luck - you’re gonna need it.” With the board outline specified before circuit design even begins, you may end up adding or subtracting features and performance based on what can fit within the prescribed shape.

Most of the boards I have done fall somewhere between these extremes. There are varying amounts of negotiation, trade-offs, and give-and-take between the electrical and mechanical designs as a product takes shape. I learned early on that some “requirements” aren’t really required, and some “suggestions” carry the weight of a Divine Edict.

I haven’t used this yet but it sounds like a great idea!

Dale


#9

I don’t think I hit the hotkey for “toggle lock” by mistake, I don’t even know which hotkey it is. I was able to draw a box around the footprints and do an unlock, its all working good now.

I am reading the Pcbnew document that opens when go to the help tab. Presumably this goes to the kicad-pcb.org > Pcbnew document that is online through an Internet connection.
–Larry


#10

In this case I know what PCB size I need, so yes, I did the board outline first. Good to know that it is optional as to laying out the board first or laying out the footprints first and then do a board outline encompassing them.
–larry