Re: gEDA-user: is gEDA a good choice for designers?

[Dan McMahill <dan@xxxxxxxxxxxx>]

Dan McMahill wrote:
> Steve Meier wrote:
> 
>> 3) Do you need back anotation?
>>
>> If you answer yes to any of these then geda/pcb isn't there yet and may
>> never be. If you would like to discuss your project requirements either
>> here or more privately don't hesitate to ask.
> 
> depends a bit on the flow.  Using gschem + gnetlist to drive pads layout 
> seems to work and backannotation does work there.  Although for some 
> reason it looks like the documentation vanished when everything moved to 
> the wiki :(
> 
> -Dan

correction, I found it.

http://geda.seul.org/wiki/geda:fbabgapp

There is some limited ability to do this with pcb too.  By limited, I 
mean you can use the Renumber() feature in pcb and then backannotate 
that to your schematics.  You can't, howerver, currently manually 
renumber, add components to the layout and backannotate to schematic, or 
do gate/slot/pin swapping, or package changes and backannotate to the 
schematics.  Of course I'm of the belief that if you're doing analog 
design you don't really need those features.

I think the only hard part in more fully implementing a more full 
featured forward/backward annotation flow is a netlist comparison tool. 
  But the tool needs to be able to match a topology without needing to 
know the netnames or the refdes's.  In other words it needs to be able 
to tell you that

R1 (node1 node2) resistor r=10k
C1 (node2 ground) capacitor c=0.1u
C2 (node1 ground) capacitor c=0.22u

can be the same as

R3 (in out) resistor=6.8k
C3 (in ground) capacitor c=0.1u
C4 (out ground) capacitor c=0.1u

if you do

R1 -> R3
node in -> node node1
node out -> node node2
value C2 -> 0.1u
value R1 -> 6.8k
C1 -> C4
C2 -> C3


Once you have that, you can produce a change file which can be reviewed 
for sanity and then applied in either direction.

-Dan


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