De Morgan alternate symbols

Apparently not anytime soon (!425). While the old file format had supported it, it got knowingly broken with the new file format implementation in KiCad 6. Use Altium instead.

To return to the original question: using DeMorgan equivalents outside logic symbols.
'I do this on a “need to” or “nice to have” basis.
The mosr comprehensive example is probably single opamps without a separate power unit.
For those I generate a DeMorgan equivalent with swapped inputs. This leaves the rest of the symbol including power pins intact. Very useful and time saving.

Fpr logic design, I use DeMorgan equivalents all the time (just as suppliers like TI and Nexperia). It results in very clean schematics, ahowing signal function and signal assertion level separately.

If someone wants to pursue this, I can recommend:
William I. Fletcher, “An Engineering Approach to Digital Design”. Reckon with $100, fully worth the money.

Not sure what you mean?

My key question/takeaway: If DeMorgan alternates are based on logic equations, isn’t it something of a misnomer to call my two BAW56 symbols DeMorgan variants? Yes I am being nitpicky, but I think we are really getting at any alternate symbols representing the same device? So if we are just drawing op amp power pins differently or repositioning the two diodes in a common anode symbol, that is an equivalent symbol but is NOT a DeMorgan equivalent, right?

Note: I do power and analog but try to avoid logic in my designs. Does that make me illogical?

Actually I recently did use a 74HC4020, a 74HC138, and an NL7SZ97 so this business of avoiding logic is only an un-fulfilled aspiration.

Right!
Two diodes with anodes common and a resistor tied to +, with respect to the cathodes, will have a DeMorgan equivalent, but two diodes with anodes common are just two diodes with anodes common however they are drawn.

Wait, maybe De Morgan did tinker with diodes in his spare time, and the historians just didn’t know. :rofl:

ML9104 writes about opamp symbol with power pins integrated. If you mirror such symbol along X to have + and - inputs swapped you get + supply at bottom and - at top. To avoid this he just makes DeMorgan (the name of flag in symbol definition) with + and - swapped.

So, if I understand correctly: Altium supports alternate symbol representations in general (not limited to De Morgan logic equivalents)?
And for KiCad there is code ready to merge, but the KiCad developer team refuses to have this new code and want to have only the De Morgan special case?

I’m not sure I quite understand why one would refuse alternate symbol representation ability, especially when code is already offered. (I could imagine that someone would find it tedious to implement if there is no code to begin with.)

He died in 1871. Did they have diodes with which to tinker in those days?

Ah you’re no fun. :stuck_out_tongue_winking_eye::grinning:

If I remember correctly, it’s limited to 100 alternative shapes in AD while KiCad 5’s internal structure and file format would have supported more (without changes). My understanding is that some KiCad developers felt it would complicate internals too much for themselves when they’ll eventually move to real databases for symbols and implement more DRC/ERC, and that the implementation they had in mind for them would solve it much better. Currently, I’m not attracted to their database solution at all (as a KiCad user I’m not a DBA), and I think it’s not aimed at the users that would use alternative symbol shapes either.

I guess it’s somewhat similar like with the autorouter; it’s too big for the current team to spend resources on it.

But I’m always trying.
I’ve often been told I’m trying. :slightly_smiling_face:

I never said I like the name, but I don’t decide, that’s up to the KiCAD team.
“Alternate symbol” would work just as well and be more inclusive of other uses.

Did he rectify the wrongs of the hysterical historians? What a pain in the anode!

Now now, no need to get heater up about this.

Well I have made an attempt to put an alternate symbol into my own library, and I am stuck. I am using 6.0. I had a look at:

and have a question similar to what a poster asks there. I am at this


and I do not know where to go from here??

The next step is in the editor window. At the top you will find two buttons for the two graphics.

demorgan

Ahh! Bitten again by picture menus instead of verbal ones! (Note I did not say “symbol” menus. The double meaning is too uhhh uhhhh?)

That gets into the whole international thing. I am one of those monolingual English idiots. But what if the menu was in German or one of the many languages which I do not know? I often think that it would be easier to deal with that (I should be able to Google it!) then to look up a picture.

Anyway I am midway along taking advantage of this assisted Eureka! moment…

Son of a turkey! It seems to work!

But I did cheat in one regard…I was working on BAT54C which in my library was already derived from my BAT54C-1. I could not figure out how to delete my BAT54C. So I zipped a copy of my diodes symbol library for backup, and then deleted the BAT54C using the notepad text editor. That seemed to work.

Then went back into KiCad and did a SAVE AS from BAT54C-1 to BAT54C. Then edited the properties and clicked the De Morgan box. Saved it. Went into my BAT54C-2 and copied all portions of that symbol into the scratchpad memory. Closed BAT54C, opened my BAT54C, clicked on the De Morgan alternate, deleted what was there and pasted what I had copied from the BAT54C-2. It sounds more complicated than it felt when doing it.

I would like to delete my BAT54C-1 and BAT54C-2 but I am probably using them in some designs…

I use deMorgan mainly for microprocessors. This makes it possible to get the I/O pins at the position where they are needed. Would be nice to have more than 2 variants.

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.