> At 02:43 PM 4/5/01 +1000, Thomas wrote:
> >Is it possible to assign multiple nets to a bus where the individual nets
> >are not consecutively numbered.
> >
> >i.e. for a bus of nets D0 to D7 I can use D[0..7]
> >
> >but what about a bus of nets FA, FB, FC, FD etc...?
>
> No, I think that is not possible. You can make a pseudo-bus, because it is
> the net labels that count, but if you want to go off-sheet, you will have
> to use either nets global or make a port for each net. I don't think I've
> seen a CAD program that would do an alphabetical sequenced bus.
>
> Solution: use numbers if you can. What's wrong with F1, F2, F3.... or F10,
> F11, F12, F13.... if that's the point?
>
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> P.O. Box 690
> El Verano, CA 95433

The most important reason for wanting non-numbered bus nets is where you
want
to maintain a control-signals bus. This bus may appear on many diferent
sheets
of the project, with only a subset of the bus signals used on any one sheet.
It's a pain not being able to use a single port to represent such a bus.

The alternatives become:
1/ use Nets global (which may impede other aspects of the design), or
2/ bring only the used control signals onto each sheet (which destroys the
neatness of a "bundle" approach).

I see no reason why a CAD package should not attach "smarts" to a bus so
that,
rather than being a just a line, it maintains a list of nets connected to
that
bus. Very simple utilities would allow immediate inspection of the list
(e.g.
informing you that nets SPI_CS_RAM, SPI_CLK, SPI_MISO and SPI_MOSI are
attached
to the bus named SPI). If the list instead showed that SPI_CS_RAM, SPI_CLK,
SPI_CLJ, SPI_MISO and SPI_MOSI were attached, it's pretty easy to see that
SPI_CLK was misspelt on one of the sheets attaching to the bus.

Alternatively (and probably better), one could pre-configure the bus so that
an
error is flagged if you attempt to connect a net that is not in the bus
ownership
list.

Just my $0.02

Cheers,

John Haddy
Cisco Systems WNBU
Level 2, 3 Innovation Rd; North Ryde NSW 2113; Australia
PO Box 617; North Ryde NSW 1670; Australia
Phone: +61 2 8874 5406; Fax: +61 2 8874 5401


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