Schematic Footprint Help


#1

I’m trying to make a schematic footprint and I’m confused by the pins for CS and SW. Could someone help me? http://www.issi.com/WW/pdf/31FL3733.pdf


#2

It appears that there are 12 pins (“SW1” through “SW12”; pin numbers 2 through 4, 6 through 11, and 13 through 15 on the IC package) devoted to selecting the rows of the display matrix. There are also 16 pins (“CS1” through “CS16”; pin numbers 16 through 19, 21 through 28, and 30 through 33 on the IC package) used to select the columns of the display matrix.

To decrease visual clutter on the schematic it may be helpful to represent these as two (or more) buses, rather than individual connections.

Dale


#3

First, a correction. The “thing” you appear to want to make is a “schematic symbol”. Hate to seem to come across as nit-picky, but that is the correct term you want to use to get good Google results.

Second, that datasheet sorta SUCKS.

Based upon the datasheets schematic symbol, at first I did not understand dchisholm’s reply above. In order to create an accurate schematic symbol in KiCad, the pin description on page 4 of the datasheet, and the actual pin configuration for the device on page 3 contains the information to recognize what is missing from the schematic symbol.


#4

How would that be done with the oddball spacing of pin numbers?

ON EDIT: NEVER MIND… temporary blank state of mind.

For others:
The Bus lines are for visual connection on the schematic of labeled nets as such to make the schematic easier to READ/understand by humans. However, KiCad is NOT human, and does not need this visual cue to make the RatsNest connections on the actual PCB.


#5

Even worse, KiCAD calls those ‘components:wink:

How would that be done with the oddball spacing of pin numbers?[/quote]

The SW pins go from 1 to 12, the CS pins go from 1 to 16…?
Just connect them to a bus each if you need a bus visualization or need to go between hierarchical sheets. Otherwise I’d just put local labels on them and use those.


#6

That is certainly NOT going to make it easy on a newcomer to get the correct search term. I did not notice the terminology in working with KiCad. However, I do note that the search terms, “Schematic Symbol” and “Component Symbol” are “mostly” the same results currently.

But, I DO agree with you, as “Component Symbol” in Google also brings up the symbols that are used in the dash of automobiles to indicate which “component” in the car requires attention.

Yea, that is what the datasheet seems to indicate on it’s schematic symbol. Read the details on pages 3 and 4 and reply back. It’s why I thought dchisholm’s post was wonky.

Dchisolm was spot-on and it is the datasheet that is wonky.


#7

Yeah, KiCADs heritage is based in the french language. Thus the sometimes (still odd) names for things. Most probably due to word-for-word translation.


#8

If you’ve followed the Kicad development over the last three or so years, you’ll see that nomenclature shifts. Footprints used to be called “modules” (which, I suppose, is worse than “decals”). “Symbols,” “Components,” “Parts” are all used interchangeably to indicate the things you put on the schematic.

But here’s where things get interesting. Some of us don’t like the whole CvPCB design flow (place symbols, draw wires to connect symbols, associate footprints with symbols, export netlist to PCB) and instead we put the correct footprint for our components in the symbol’s “footprint” field (and we may add and populate a Part Number field, too). We tend to call these symbols “components” or more fully “atomic components” (or “parts” or “atomic parts”) because they contain all the information you need to not only make a PCB but also to order parts used to stuff that PCB.


#9

I would say ‘not like’ is too strong a word/concept - for me it’s more like ‘unfit for my personal workflow’.
To the contrary - I definitely like that other people who have a different workflow and have no desire for atomic parts, can use the more simple CvPCB workflow.
Live and let live.
:hugging:


#10

(My, my . . . . haven’t we pulled this thread off-topic? :confused: I wonder if @kjfsaaf ever got his symbol and footprint built?)

I wouldn’t say that CvPCB is “more simple” . . . . but it DOES direct your attention to only one type of task at a time. That’s an advantage for those of us who find it difficult to walk and chew gum at the same time. It’s a disadvantage to those of us who get intimidated by a long “to do” list of tasks that must be done in the process of laying out a board. Personally, I hardly ever use CvPCB to assign footprints to a large number of schematic symbols, but I almost always use it to verify that all of my symbols have an assigned footprint. Occasionally I use it to assign an alternative footprint, more suitable to the particular application at hand.

KiCAD offers a great deal of flexibility in how you accomplish many basic tasks. (The OpenGL canvas versus Traditional is perhaps the foremost example.) This flexibility is a two-edged sword. It allows a user to select tools and methods that seem “most comfortable” or “most familiar” . . . . provided we know the choice is available. On the other hand, it confuses users who are faced with the choice of “You can do it {this way}, or {this other way}, or {yet another way}.” As you work with the program you will undoubtedly find alternative approaches that are either better or worse than what you previously used.

When I began my journey with KiCAD about 18 months ago I pretty much worked with one hand on the mouse, and the other in my pocket. Now I work with one hand on the keyboard, and the other split 80/20 between the mouse and the coffee mug. That’s changing, since the cardiologist says I need to stay away from real coffee, and the decaffitated stuff is a wretched substitute. :persevere:

Dale


#11

I REALLY HOPE CvPCB stays in the game with enhancements.

I’m starting up a new business and hope to have product in production some time early this year.

Putting on the Engineer hat, I need a linear 5V regulator from a automotive ~12V source.

Putting on the Bean Counter hat, I need to keep costs down.

In the past, I was employed as a technician to assist in the re-design of a PCB to replace obsolete parts; in some circuits no need to change the schematic, just the part number and footprint.

Atomic parts are a great idea in my opinion; up to the point that the actual physical part number becomes obsolete but the electrical part is still available in a different form factor with a different part number… never mind the different part numbers for the same form factor part in different ordering formats and quantities.

At the moment, I am EXACTLY in the MIDDLE based on my own personal knowledge and experience; and I’m not really an expert.

Why not expand CvPCB to handle part numbers, footprints, and costs in the one tool?

If CvPCB had MORE functionality, it might be that even Atomic part users would find it helpful.

Just a thought…