Re: gEDA-user: Fwd: [Open-graphics] How to get more eyes on OGD1 schematic?

[Xtian Xultz <xultz@xxxxxxxxxxxx>]

Em Ter 14 Mar 2006 17:15, Stuart Brorson escreveu:
> (Regarding the OpenGraphics board)
>
> > Thats the first time I had seen a part in a "U" shape... thats very ugly
> > to me...
> > And a lot of capacitors, all in paralell,
> > the ICs withou power pins... how can
> > somebody deffend that kind of design style? (I am not saying the
> > schematic is
> > bad, I just dislike a lot that style, but a lot of people thinks thats
> > the best design style, which I cant understand).
>
> *chuckle*
>
> That schematic is an excellent demonstration of the oft-made claim
> that graphical schematics are dead, and should be replaced by
> text-based HDLs.
>
> Personally, as an analog guy I don't think the graphical schematic
> will ever die.  But it *is* true that not much real info is gleaned
> from a bunch of boxes drawn on a page.
>
> Of course, the question is: How *should* one represent a digital
> design like that one?  I mean, you still need to capture info about
> pin-outs, and placement of series term resistors, bypass caps, and a
> few other things.  But is there a better way than just drawing boxes
> on a page?
>
> I see a good PhD research project for somebody clever here. . . . .
>
> Stuart

The connectors, I draw different. I made a component with only one pin and one 
little circle. If I need a connector with 10 pins, I put and attribute on it 
defining 10 slots. That works for connectr which have only numerical pin 
numbers. 
Of course, when I use a connector with a large number of pins (the greater I 
used had 66 pins) it sucks to assign slot to every pin, but maybe in a near 
future that could be automatycally by gschem :)
Then, I made the refdes of all pins (except for the first) hidden (AT) and I 
draw a rectangle around the connector. 
That way is fine to break the connector into pieces, put part of the connector 
in one sheet and part in another, I put a text next to thge refdes with P/O 
(wich means Part Of), I have seen some diagrams like that in avionics 
diagrams, most drawed by hand (wich means they are old, but very well drawed) 
and they use really large connectors to connect one equipment to another...

The power pins, I use power boxes. I told a lot about that in this maillist, 
IMHO is the best way to show where the power goes, and to place decoupling 
capacitors (I draw 45 deg line to show that the connection must be as close 
as possible).

Finally, I tend to brake large parts in smaller boxes, putting GPIOs from one 
port in one box, other port in another, osclilator, reset, JTAG, etc in 
another, and so on. Its better to see small boxes than a large box. 
That makes sense. If you think in a old TTL logic IC, like 7404 wich is (if I 
remeber well) 6 inverters. The normal way to draw it is not to put a single 
box with the inverters inside (except the Jedec specification, but a few use 
that) so the normal way is to draw the inverter symbol around the sheet, and 
put a slotdef for every one. Why not make that with large parts, like a 
microcontroller? Why not put a port togheter in a box, and have some boxes 
with some ports on the sheet(s)? IMHO, that makes sense.