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Re: gEDA-user: Task list for: Solving the light/heavy symbol problem

Mike Bushroe wrote:

> but could the 'packet' of data also have choices for alternate naming
> in the schematic of pins with multiple uses? 

Is this supposed to configure individual pins? Or is it more like whole 
ranges of pins used either as analog input or as digital output? I
think, we need both :-)

For individual pins I propose an extension of the pin attribute concept.
Add a comma separated list of alternatives in an attribute like this: 
The gschem GUI would present a drop-down list of these alternatives in 
the attribute editor. It is a way to give a choice of default values for
the pinlabel attribute rather than just one as we do now. This technique 
may be applied to every attribute. It does not affect the notion of packets 
at all. 

For whole ranges of pins the packet may contain alternate sub-symbols. 
These sub-symbols shall bear a unique label. The scope of uniqueness 
of the labels is just the current packet. So it is easy to meet. 
These labels are used by a be a set of rules that tell the system which 
sub symbols are alternates, which sub symbols are required (e.g. power) 
and which are optional. The rules are be attributed individually with 
a policy flag to tell the system how to treat violations ("enforce", 
"warn", "ignore", ...). The default of the policy flag is set at design 
time of the packet. It can be overridden by the user per instance of the
packet in the schematic.

> You would also have to allow
> for the fact that the DIP part is often limited to 40 pins, but the TQFP has
> 44 pins, and when they have one the BGA is 49.

This is the pin mapping theme again. The packet may, no, should contain
a scheme to map symbol pins to footprint pads.   

Kai-Martin Knaak
Email: kmk@xxxxxxxxxxxxxxx
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