On 12:32 PM 14/03/2001 -0800, Abd ul-Rahman Lomax said:

>At 08:29 AM 3/14/01 +0000, Coleman, Tim wrote:
>>With regard to power pins on multiple part components(or even large single
>>part components like a uP or memory). We create a 'power part' that has just
>>the power pins and any NC pins. This part of the component is then placed as
>>part of the power distribution and if a de-coupling capacitor is required it
>>can be placed directly on the pins of the power part of the component.
>This is an excellent way to go, but it does require making one's own 
>parts. I would also note that if one neglects to place a power section for 
>a part, no rule, as far as I know, will detect that it is missing.
>If one follows Mr. Coleman's practice, it would be useful to be able to 
>generate an unconnected pin report. This would detect all pins on the 
>schematic *including pins on unplaced sections (which exist in the 
>cache)*; it would report all pins which are unconnected -- probably by 
>comparison with a netlist if it is a server we write -- and would 
>specially flag unconnected power pins.

I have been wanting a more elaborate rules system for Sch for some time and 
have raised the issue before to see what rules the group would like. That 
seems to the logical extension of these two interlinked hidden pin threads.

Suggestion: An attribute (per section/part of a multi-part component) in a 
sch library that says this "part must be placed". The ERC could then check 
that for each symbol the required "must place" section(s) is/are 
included.  (David Cary - did you get that for your features database?)

Personally, I would mark *all* parts of my multi-part components as must 
place.  This ensures spare gates etc are visible and any floating inputs 
are detected. Like others I am a firm believer that the sch must be 
complete and show every pin. Design review, debugging, test and future 
improvements are made so much easier not to mention the improved ability of 
the ERC system to detect problems.


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