gEDA-user: Non-Rectangular PCB Shape, Negative Etch, 3-Spoke Thermals; Swapping

[Gus Fantanas <fantanas@xxxxxxxxxxxx>]

I am using the gEDA suite that was packaged with Ubuntu 11.04 "Natty." I 
have three questions which I detail below:

1. What can I do if the intended PCB shape is not rectangular, e.g. if 
it is circular? I intend to "palletize" the PCB (if there is any such 
word), that is, to fit several regularly arranged copies of it on a 
bigger PCB and then separate them. It costs less that way. I remember I 
read in the scattered gEDA documentation about some cumbersome way of 
coming up with non-rectangular pcbs using one of the layers, but I am 
not sure where I read it.

2. On the same layer, I want two different grounds which come together 
within a small area (a very common occurrence when laying out an ADC or 
DAC). I can draw two patches and then connect them with a trace. It 
would be easier if I could draw one big patch and then introduce /cuts/ 
to it by telling PCB to /remove/ copper where I draw a trace. Is there 
any way of doing that?

3. I remember reading somewhere that there is a way in PCB to cycle 
between different kinds of thermals (three-spoke, four-spoke, or none). 
I am not sure it that was an experimental version of PCB. My installed 
version only offers the four-spoke option âor, at least, that is what I 
have been able to findâ and I can reduce the spoke length to zero (via 
directly connected to the copper plane) by repeated application of 
<SHIFT>K. Is there a way to tell PCB that I want a three-spoke thermal?

4. What is the current status of swapping in gEDA? I did some spot 
checks on the 7400-series gates that came with the installed libraries 
and did not see any pin-swapping or gate swapping information in their 
attributes. Google shows there has been a lot of discussion about gate 
and pin swapping in gEDA for over a decade.

I did quite a bit of searching before posting these questions, so I hope 
I am not wasting anyone's time.




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