I agree with you regarding the use of symbols which match the physical pin layout of the components themselves. A long time ago, I used to draw my symbols with the pins arranged however I was feeling like at the time, just like you see in the CAD libraries. At one job my (much more experienced) boss insisted that all the symbols have pins in sequential order. No rearranging allowed. He said it made board optimisation much easier – he was right. Since then I’ve tried to make my symbols resemble the physical parts for that reason.
It’s a bit odd to see so many people here say it’s a bad idea. I suspect they haven’t even tried to do it this way. In my opinion its the best way to draw any symbol for any part which is programmable, a connector, or an array of smaller parts.
The trouble is the symbol creation tools in Kicad are a bit crude. Pins have to be created one at a time which is very tedious. In other PCB programs it’s possible to create many pins at once, with a name that increments sequentially. This way it’s very quick to enter new symbols for microcontrollers, etc. It’s also very quick to do a check by comparing the new symbol to the pin arrangement diagram in the microcontroller datasheet. When it’s fast to create and check new symbols, I find I have no desire for symbols made by others.
Have a look at Sprint Layout. That’s the one I’ve heard the most positive remarks about. I haven’t used it myself because I don’t have much use for ‘straight to layout’ type PCB software.
Grab a service manual for any piece of consumer electronics equipment made in Japan in the past 30 years. Look at the schematic symbols. Chances are that the symbols for ICs, connectors, transformers all directly resemble the physical parts. They do that because this is the standard for this industry. I suspect it is like this for the benefit of the service technician.
To each their own I guess. I don’t do large complex boards but if I did I would probably consider it more of a logic diagram than a layout diagram putting an emphasis on being able to follow that logic. Crossing traces and playing ping pong back and forth across the diagram would serve no useful purpose in that case. Last guy I did a board for didn’t like named nets because he didn’t have a wire to follow. Should we get rid of named nets and buses?
Do you know the schematics you reference above aren’t reworks of the originals specifically for the service technician?
The funny thing is, KiCad can do that already. Just ask how.
A lot of people moan about KiCad but they haven’t taken the time to learn how to use it. Ok, so “official” documentation is not great, but there are quite a few tutorials around the web, and the best user support forum on the internet.
As for library parts not meeting niche user requirements, that is A Dead Horse to be Flogged Repeatedly.
Scripting can help with this. There’s a tool called KiPart which I’ve seen mentioned on this forum and which looks useful, although I haven’t tried it myself. (I do my own scripting in Haskell, but I’m a bit of an anomaly.)
I mean part of my frustration was trying to find something more useable than the last thing.
I suppose for this use case, since it can be largely automated, something like
right->click on symbol
select order pins
select package
done.
The edit functions are a bit clunky at best, have hit everything from file permissions to things not updating without restart. Plus ideally I don’t have to pass on extra steps to the next guy (like download this lib and that, and good luck!)
I can’t believe you didn’t stagger them for more verbiage space though bobc
also re: right click symbol-> re-order pins, bonus points if pcbnow remembers your package selection. Should probably check that it doesn’t already exist…
re: technician, for these kinds of projects, there isn’t really such a division of responsibilities.
If that methodology works for you then great, just don’t expect much support when you join a forum and start telling everyone else they are doing it wrong. The tools the op is complaining about allow him to do exactly what we wants, it’s just too much work for him to change the existing symbols in the library. He’s already spent more time complaining here than it would take to rearrange the pins on a dozen or so symbols.
30+ years ago I started out drawing schematics using symbols exactly as they appeared on the datasheet. A 4-bit BCD counter connected to a 7-segment decoder connected to a 7-segment display was already a bit of a mess. Eventually I learned to draw my schematics with signals logically grouped, and I’ve never looked back.
They are probably not quite as crude as you think, but if you believe a feature is missing or could be improved then suggest it.
Yes I have seen schematics like this but often they contain a mixture of symbols that match the pinout of the package as well as symbols that don’t. It’s as if when it gets a little too complicated or chaotic they move some pins around. Transformers are usually drawn so that the phases of the windings are aligned, this sometimes requires pins to be swapped. I suspect that rather than being a company, or even country, wide standard it is simply the preference of the person who drew the schematic. And I think most people draw connector pinouts to match the actual connector.
Please direct me to this standard you speak of.
This is the pinout for the D package of the 74192.
Here is it’s schematic symbol according to the IEC standard.
Like many other countries, Japan is a full member of the IEC.
What do your schematic symbols look like for packages that do not have pins around their periphery, such as PGA, BGA or LGAs?
PS. @steveob42 you might want to look up the definition of the word “abstract”.
Still don’t understand why the religious devotion to the church of the IEC when there are practical concerns, like interfering with the creation of a PCB. Do you just farm out the PCBnow portion and forget it or something, and you can’t be bothered? I mean that is fine and all, but should that be the way everyone does things?
And that is the problem with simplification.
The stripped out symbol has to use the bus pin names as you have drawn. To be at all usable you then have to have a text table next to it saying what is RST etc.
Until there is away of choosing alternate function names there is no easy way out of this.
a schematic is an abstract, logical representation of a system Wikipedia: Schematic
a circuit diagram exists to communicate the intend of the designer of the electronic circuitry to himself and others Wikipedia: Circuit Diagram
Only hobbyists and starters (electronics books for kids) use and draw pictoral representations of electronic circuitry - anyone else who deals with this on a regular basis abstracts as much as possible to be able to concentrate on the logic of a schematic.
If there is a need to communicate layout relevant information with the schematic it usually is done via notes or pictures. Though, the only time I’ve seen this done is when my dad was using a CAD operator to turn his schematic (on paper/LTspice printouts) into something that the fab can use to create the pcbs. It essentially boils down to him not willing to learn a CAD tool
But don’t fret, KiCAD allows you to create your OWN symbols in a lot of ways (the symbol definitions files ARE HUMAN READABLE for a reason), which means you can do what you want, even draw hydraulic systems with it.
All it takes is - YOU - to sit down and learn the tool given to you and do the leg work. We won’t do it for you.
This is on the borderline of a being a personal attack; as I have no religious devotion to any church of EDA design, nor specification.
when there are practical concerns, like interfering with the creation of a PCB.
If you are creating throw-away designs then the schematic layout doesn’t matter much at all.
However, if one is creating a design that expected to be repaired in the field, then why would you NOT create a schematic that an experienced Technician can easily follow, and get the equipment back up, and that much quicker?
[quote=“Joan_Sparky, post:52, topic:4450”]
Only hobbyists and starters (electronics books for kids) use and draw pictoral representations of electronic circuitry - anyone else who deals with this on a regular basis abstracts as much as possible to be able to concentrate on the logic of a schematic.
[/quote]1.21 nailed it. No one that has worked on a chip with any appreciable pin count doesn’t get this. If he wants to draw me a pictorial symbol of something like a 144 pin bga and prove me wrong, then he is welcome to do it. Otherwise, I’m not wasting time on it.
And the service technician is concerned with what actually?
to understand the circuitry? or
just to find the broken piece (95% of cases its a connection problem anyway) by checking voltages/states, that are pointed out in those service documentations?
A field technician/service guy is not a professional circuitry developer.
He doesn’t need to understand how something works.
He just needs to find his way around the real object (layout) vs a schematic that tells him what is what.
So unless you job is to create service manuals + schematics, you’re doing it wrong.
And this I doubt:
I want you to do this for a 100+ pin package/module + surrounding circuitry.
Any professional schematic that I have seen in the last 20+ years did group pins by function.
It’s only hobby users or slackers who are behind the times…
Prime example of what WE are talking about - note how the BCM2835 + LAN9512 symbol is broken into several pieces with pins grouped by function and then to make it easier for the hobbyist crowd - all other symbols (parts) kept pictoral and identifiable, so they are easier to find/understand for them (professionals wouldn’t bother with that):
I agree with @hack that connectors are best drawn in strict numerical order and for that matter bus entries also. That second requirement totally conflicts with using actual IC pin numbering.
When I debug a board where bus numbering is scrambled, I end up cursing the original designer as I am far more interested in the overall logic of the design than the internal details of the IC
I’m late to the party and I may be overstepping a bit. Starting a schematic before thinking about layout is a bit out of order IMO. Ok, a lot of circuits are going to have the same schematic no matter what. A 2 stage inverting amplifier is going to look like any other 2 stage inverting amplifier. I can’t imagine trying to draw a neat opamp amplifier using the actual pin layout.
Sure, you could draw it like in the datasheets with little opamps inside of the chip, but why not just draw the opamps and show clearer intent?
There are tools that help with this. They are called pin planners, or whatever marketing decides to call them this week. The larger companies offer these in their toolsets. The 2 that I use personally are STCubeMX and the pinplanner inside of Xilinx ISE/Vivado. Along with having a graphical view of the chip they will give you a nice report book and a skeleton to start coding from using the pin configurations you have selected.
My current employer isn’t small, but my current engineering/drafting/layout team consists of 1 person. I want my schematics to be as simple as possible and that is what I tell my circuit guy to do.
Either way, I don’t see how putting this much detail into a schematic is going to help when it comes to actually laying out the board. There will still need to be revisions and pin swaps as you figure out the exact positions of components.
