For what it’s worth, of all the 8+ layer boards I’ve seen in my career, only one was auto-routed, and the auto-router was only allowed to do a portion of the board after a human had done all the critical parts. None of the hand-routed ones took months and months – maybe a week or so max for the most complicated board. This is using a variety of EDA tools, and the interactive router features.
Think we have all experienced something like that! I used an option called rules based routing and it controlled the route of critical lines using rules of my making. In my case I had differential lines, and they had to be equal length and controlled impedance. Similarly, various other lines were specified not to exceed certain lengths, or got routed first to ensure integrity. There’s a lot that went into that auto-router. I used it to it’s fullest and had a first pass working to spec board. It took me a couple of extra weeks to learn how to specify what I wanted, (and it was the first release of the software) but it was worth it. So auto-routers are not all bad, at least that is my experience.
Thanks for the assurance that I don’t have exceptional needs! I will figure it out eventually. You have gone through the learning curve, I have yet to. Will get there. My personal journey…
Haw many PCBs you could design in that time yourself?
For me 90% of work is right element placement and then routing is a moment. KiCad Interactive router in most cases allows you to route a track by simply clicking its begin and end.
I use ‘Shove’ mode so if any previously routed track disturb the current one that old is simply shoved (jumping over elements if needed). Just experiment with it.
In my case 90% spend on placement probably comes from this that my PCBs are 2 layer with whole bottom GND so I really have to place everything to route all tracks (except GND) at single layer.
An example of my PCB you can see here:
Interesting. My experience was with military boards initially. We were getting really long time quotes for the job, hence my desire and motivation to use a new-fangled tool called auto-router in the early 80’s. I sat with the experienced board designers and layout guys and tried to soak in all the information I was being provided. On my own initiative, and I got a lot of heat from management over my decision, decided to try the new auto-routing tools. My story is that of first pass success. My board was done and operational months ahead of schedule, but it took 2 weeks longer in the layout phase to understand how to use the tools correctly. If I recall correctly, as a young headstrong engineer, I never got extra pay or reward of any sort for daring to buck the system and being two months early with my delivery.
Fortunately for me, I didn’t have to design any extra PCBs. I was in charge of delivering a product, which was 1 PCB that met all it’s specifications and was on schedule. To be honest, laying out PCBs seems tedious (at the moment, because it is hard for me), rather be doing something else that is more fun. Just doing it because it needs to be done for something I’m automating at home. For me, the fun is in the creation of the system that does the automation, and testing it, rather than in laying out a board. Different ways to float one’s boat.
Totally agree with the right element placement. Once I get the board in place and make the display footprint, it doesn’t look all that bad to route by hand. For me, it is just getting used to how to use the PCB Editor that will take a while. I will hack about with it for a few days.
Seems to be an area of great controversy, although I don’t honestly know why. I successfully used an auto-router in the 80’s for a dense military design. The art, and it is an art, is to specify enough rules so that it is possible to get what you want, without ending in a locked no solution mode. Like layout itself, it requires a bit of intuition and skill. It can be done, indeed it was done in the 1980’s by Mentor Graphics, because I was one of the first users of that tool. Can you get a mess, sure. Does it absolve the designer of reviewing the layout, NO! Even if it gets you only 99% of the way there it is worthwhile since you can manually fix the rest. This collapses development time, which means either you, or your group is more productive. Despite all the horror stories contained in the threads posted, my experience with commercial auto-routing has been positive. However, one cannot blindly trust it. The router needs to be constrained with sensible, necessary and sufficient rules. All I know is when I adopted new tools to help me with my designs, I was able to complete the designs in less time. To ignore technology like this just doesn’t make sense. Instead, we should be trying to make this sort of tool more useful and accessible. Personally, I think it would benefit the community.
I get the old school part of this argument. There are some things I’d rather do in traditional ways, if the results are good, and the experience gratifying. But sometimes you have to use modern tools, or you simply won’t be as productive as the person that does use them. So you won’t get the job, because it would take too long, or cost too much. Or you give up, because it will take too long. Quite honestly, in the past, I have given up on creating personal PCB’s because the software was painful to learn. At this point, I do have some additional motivation to learn the tools, so I will go through the process.
As a hobbyist, sometimes I am forced to do things the old way, because the new way is too expensive, or perhaps incomprehensible. But tedious and unenjoyable stuff, I want to automate, and if a good auto-router was around, I’d use it. Because in my case, I used the auto-router, verified the output, and it did a great job, (I checked all critical routes and sampled 50% of the rest of the routes) and it did it in a fraction of the time that the designer could do. So my experience is favorable. 98% of the time one doesn’t need an optimal layout, just one that is good enough. As long as the board performs good enough, and isn’t a mechanical nightmare, I’m happy.
Back from the distraction of the Autorouter
The grid is sort of self explanatory. See green box and red arrow, both repeated in View (blue arrow).
Just change grid as you wish when you wish.
Of note:
Holding Ctrl + Alt down will disable the grid completely (while those keys are held down), if you wish to move something with the mouse off grid.
Take note of the Cyan box at the bottom of your work sheet. X & Y give position of the mouse with respect to your origin. dx & dy are useful for critical placement of stuff… Hold mouse over part “A” (or whatever), tap space bar (which will zero dx & dy) move mouse to “B” or whatever and read off the distance between A & B on dx & dy.
Moving along a little. I think I have been able to make a footprint, that consists of a 1x14 2.54mm pin header and 4 NPTH. I want to put an outline around everything which shows me the extent of the display. This helps me size the PCB. That just goes on the F.Silkscreen? The NPTH in the pad editor state F.Cu and B.Cu, that is what I want? That means the footprint holes go all the way through?
Here is a courtyard question. Is this basically a keepout? Does KiCAD know not to route through a NPTH? Do I need to make anything extra to keep traces away from the holes? In my case there may be a nut on the backside of the board. So do I make a courtyard circle around each hole? Or is courtyard for continuous areas? Sorry for the basic questions, there’s lots to learn!
That is the courtyard. For just personal information you could use a “user” layer. Silk is for what you want printed on the PCB
Yes.
No.
Yes, however if you need to give the hole clearance. Go to File / Board setup / Design rules / Constraints.
Lots of stuff there including hole clearance.
In fact, lots to read in Board setup.
Almost there… Been a long day. Here’s a render of the basic board so far. Still have to do the power plane, which has a split. All routed, save for the power connections. Caps are in, and grounds are done. It’s quite primitive, at least according to this forum’s standards, but it is my first board done using KiCAD and the first PCB I have done in 39 years. Thanks for getting me going!
renderboard.pdf (62.1 KB)
And you’re the president of this industrial complex?
Good job.
Worth pointing this out because it once bit me… Consider the thickness of the USB connector that plugs into it… Some have good size such as to lay against the PCB. I always include a Cutout on the PCB for this…
Oh, yes! I have been burned by that before. Also by standard USB A cables that seem to be molded extra thick. I have been known to machine USB connector bodies because I couldn’t put in two connectors in a stacked USB connector. (RPI4)
Thank you for that warning though. Think it would be a good idea tol put in a cut out for the connector body.
That’s my story, and I am sticking with it!
Have a question about split power planes. Need to make a +3.3V island inside of a +5V plane. How does one go about doing this efficiently? Put in the +3.3V region, then the +5V surrounding it? Will KiCAD automatically put in the boundary surrounding the +3.3V area? The split plane will be on In1.Cu. I have a ground plane on In2.Cu, with wiring on the outside planes. Thanks!
splitplaneQ.pdf (11.5 KB)
Use “zone priority level” in the zone settings. It doesn’t matter what order you create the zones in; it just matters what this number is set to (higher numbers fill first).
Seem to be having an issue with the inner zone vias 3V3 not picking up the plane. I don’t see the thermal reliefs, like I do in the +5V plane, or for that matter the gnd plane. I made 3v3 priority 0, and 5V priority 1. Can’t wire up the processor pins or have them connect to the 3v3 power sub plane. What bothers me is I cannot see a boundary between the split planes. There should be something visible!
You want the inner zone to have a higher priority number, so it will be filled first. The outer zone will then keep clearance to it.
Zone boundaries are visible; by default as a polygon with hatch lines on the inside. Can you share a screenshot of what you mean?
I can show something, but I am not sure what to show. It seems when ever I rerun DRC I get different errors. Sometimes the pads connect to the planes and sometimes not. I see two zones but no discernible cut. I may have mixed up the planes by accident! Let me unravel that first. Maybe that will solve the problem.
When I do show something, what are you looking for? The whole file? Or?
I meant a screenshot of your window; but attaching the file is fine too.
Have you used B
key to refill zones?