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Re: gEDA-user: European symbols?

On Jan 1, 2011, at 1:24 PM, Johnny Rosenberg wrote:

> Den 2011-01-01 18:42:49 skrev kai-martin knaak <kmk@xxxxxxxxxxxxxxx>:
>> Johnny Rosenberg wrote:
>>> here's a
>>> new try, which I tested several times:
>>> http://ubuntuone.com/p/W8l/
>> I just looked at 7400-IEC-1.sym. Some comments:
>> * some lines of invisible text is not on 100 grid.
> I took a look myself and you're right. I didn't make those though, since I just modified an existing gate, so I guess they are not on ”100 grid” in the original symbol files either, but I didn't check that yet.
> I didn't add or modify any invisible text except those very unnecessary (?) author- and license lines. I guess I should remove them entirely.

You should have them if you intend to publish on gedasymbols.

>> * the footprint attribute is invisible
> Didn't change that either. Why would you like them visible?

Matter of style. Kai-Martin has his, others have theirs. I prefer the footprint invisible so it doesn't clutter the schematic. If I want to know the footprint, I look in the BOM.

>> * pin labels are invisible

Another matter of style, when the symbol itself is sufficient to deduce function.

>> * if pin labels were visible, they'd collide with the box

But they are invisible.

>> * pin length is 200 units. IMHO, these lengthy pins result in
>> awkward artwork, when there is little space on the canvas. This
>> is of course a matter of taste.
> 200? Strange. Strange. Looks like 300 to me, except the output pin, which indeed is 200. I didn't change that from the original symbol either, though.
> Actually, the only thing I changed was the shape of the box, and I added an & sign inside…

Another matter of style. Do it how it looks good to you: they are your symbols.

>> * the slot attribute is invisible. I like to make it visible, so
>> it is explicitly shown on the schematic and can be edited on mouse
>> click.

I personally prefer it invisible. Do as you please.

>> * there is no value attribute --> this attribute is used in the bill of
>> materials

There's no common convention here. I often use the device attribute for this purpose. Then value is for things like resistors. Whatever makes sense to you.

>> * the visible string 7400 is simple text. That way, it cannot be edited
>> in the schematic. In a real circuit it should read 74HC00 or whatever
>> flavor of TTL logic should be used.

That's an old convention. Due to Ales? I usually agree with Kai-Martin on this matter of style (but on some days ...). Use device= or value= to identify the component if you like.

>> * the supply nets are implicitly given with the net attribute. IMHO,
>> this approach hides information that should be visible in the
>> schematic. I prefer to put the power pins in a dedicated 74er
>> power symbol.

Another matter of style, where I again generally agree with Kai-Martin. I even use the power symbols he posted on gedasymbols. But do what makes sense for *your* flow.

>> * suggestion: If the symbol complies to a specific IEC norm. How about
>> a comment, that refers to the specific norm?

Good idea.

>> * what is the intended use of the attribute device=7400 ?

Another style is to use device= as a generic identifier (7400), and put the complete part number in value=, e.g. value=SN74HC00D or some such.

> Don't know, I didn't add that, so it is probably the same as the original symbol.
>> ---<)kaimartin(>---
> If it's not too much work, could you modify the 7400 symbol to your likings and then send it back so I can modify the other symbols accordingly?

Your symbols should fit your prejudices and intended use.

John Doty              Noqsi Aerospace, Ltd.

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