Re: gEDA-user: PCB format wishlist

[Steven Michalske <smichalske@xxxxxxxxx>]

On Sep 4, 2010, at 4:50 PM, Ethan Swint wrote:

> In parallel to how we want to implement the PCB file format, why don't we have a separate thread on *what* we want to implement?  I'll propose the following as a starting point:
> 
> 1) Better angle support: include rotation (in degrees, rotation/translation matrix, whatever) as a location argument instead of altering the pad/pin/silk/refdes/whatever location data separately
> 2) Footprint re-use: reduce file size by having components refer to a 'base' component with XYRS information, make component tweaking easier. Say you wanted to change all your 0603 resistors - it's easier to change the fundamental component, rather than the present case of to modifying individual components in all of their rotations.
> 3) Connectivity information: include the connection information between line segments, similar to (but not necessarily exactly!) SVG format, where multiple points and arcs can be included in one line.
> 4) DRC re-use: refer to a 'base' DRC rule, rather than re-describing the DRC at every instance.  DRC rules could be arbitrarily complex or simple, e.g. elements in DRC class '250V' must have a 0.050" clearance from class '5V', but can have 0.010" clearance within '250V', or something along the lines of the 'skinny, normal, fat, power' we have in place now.
> 5) Ability to lock any portion of the location coordinate, either in absolute or relative to another entity (line segment locked to pin/pad, components locked to the same Y coordinate, etc) - rather than just specifying an absolute coordinate.
> 
> We might not be able to use this flexibility until PCB's internals are modified, but the ability will be there, waiting to be tapped.
> 

I think that we should start from a bit lower level an include discussions of wishes for footprint file format as well, because currently footprints are a pcb file snippet.


Desires for PCB footprints:

True solder and paste mask layers. (could be converted to pads with no copper and the proper mask clearances set in the current PCB data structures)
keepouts:
	- Mechanical: no components in these places.
	- Electrical:
		- No surface copper. (housings, connectors)
		- No internal copper. (antennas)
Alignment points:
	- board edges
	- board slots
	- mating connector alignments

glue/potting/underfill points.


Any other thoughts?

Steve

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