At 06:21 AM 9/14/98 -0700, Wolfgang Schenke wrote:
>We at www.rsi-inc.com have designed a program called DELTANET, which can
>compare BOM and NETLIST data at any stage of the design and create a diff
>list, which the user than can evaluate the result and make the necessary
>modifications.
Many years ago I ran into the problem, as an independent PC designer, that
I did not have control over the schematic, yet I would run into situations
which required netlist changes. If I were to wait for the one who
controlled the schematic to change it, the job would be delayed, and since
there were, not infrequently, several of these changes, discovered at
different points in the design process, the delay could be quite significant.
So I wrote a utility in QuickBasic which makes changes to netlists through
a readily readable and understandable ASCII text file. I would then use it
to make the changes and complete my design. The text file was sent to the
engineer for approval, and, while they did not always do it, I encouraged
the engineers to change the schematic accordingly and generate a new
netlist, which I would then verify through the normal DRC process of my PCB
design program.
The file used to change netlists I called the .UPD (for Update) file, and
its syntax was very simple.
The first section made pin substitutions. "U3-GND,U3-2" would convert all
instances of "U3-GND" in the netlist to "U3-2". This was used to correct
pin names (as shown in the example) to names used in PC library parts, if
that was, for some reason, to be preferred to changing the library parts
themselves (such as the source schematic was not internally consistent), or
to swap gates or the like.
The second section would move pins from one net to another: the syntax was
"[pinname],[oldnet],[newnet]". This was also used to add new pins (by
leaving the [oldnet] empty, or to remove pins, by leaving the [newnet] empty.
These two commands can be used to make almost all changes to a netlist, and
the program sufficed me for years. Some time back I added a feature to the
netlist, an ability to specify a net used in the second section by
reference to a pin connected to it, rather than by the net name. Looking at
a schematic, referencing @U5-3 was a lot easier than digging through the
existing netlist to find that this net was named N_00231.
I never did make a footprint equivalent to this update file, since it was
totally normal, in my business, for schematic references to footprints to
be completely different than those actually available to me. If I were
working for just one customer, or just one company, I would have made the
effort, so that future schematics would automatically provide me with
footprints.
I still sometimes use the program, even when I have access to the
schematic. It can be substantially faster to make a change directly to the
netlist through my utility than to go back to the schematic, change it,
recheck it, generate a new netlist, and provide that netlist to the PCB
program. My customers are often in quite a hurry for the PCB design, and
using my utility, or one like it, can be quite a timesaver. Yet it still
documents all changes, so that they can be verified and incorporated back
into the schematic.
I also wrote a program similar to the description from Wolfgang of
DELTANET, which created .DIF files by comparing two netlists. I had much
less use for that; it was mostly useful for making changes to a board when
there is no change information available, only a new, revised schematic.
[log in to unmask]
Abdulrahman Lomax
P.O. Box 423
Sonoma, CA 95476
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