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OrCad Capture power pins

M

Malcolm Reeves

Jan 1, 1970
0
Hi,

I can't seem to find a good way of having logic gates on different
rails.

My options seem to be:

Edit part to change power name for each part.
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?


--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
([email protected], [email protected] or [email protected]).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - www.CharteredConsultant.co.uk - The Consultant A-List
 
J

Jim Thompson

Jan 1, 1970
0
Hi,

I can't seem to find a good way of having logic gates on different
rails.

My options seem to be:

Edit part to change power name for each part.
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?

I'm heading to the airport, to Pittsburgh for a few days. Will show a
trick when I get back.

...Jim Thompson
 
K

Ken Smith

Jan 1, 1970
0
Malcolm Reeves said:
My options seem to be:

Edit part to change power name for each part.
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?

In the DOS Orcad, you could make passive pins that appeared only on one
part in the package. Such schematics import into capture ok so I assume
you can do the same in capture, but this may not be true. I've discovered
that some things that are quick and easy to do in the DOS version don't
seem posible in the windows software.
 
G

Geo

Jan 1, 1970
0
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?
Rubbish :)
Hidden power pins are a complete PITA to a service tech. When you come to
service the product, the circuit MUST show which supply each chip is connected
to. And preferably on the chip not in some hand-typed table...
Geo
 
N

Ned Forrester

Jan 1, 1970
0
|> Hi,
|>
|> I can't seem to find a good way of having logic gates on different
|> rails.
|>
|> My options seem to be:
|>
|> Edit part to change power name for each part.
|> Make power pins passive and thus visible on all gates and connect.
|>
|> Both seem naff to me. Is there another way?

Well, I don't think you would want the first option. That would hide
the power connections so that you would not be able to see what rails
they are connected to.

In Capture, you can select the part, and then right click and select
"Edit Properties". At the bottom of the dialog box, check "Power Pins
Visible". Then you can wire the pins to whatever rails you want. I
THINK (check this) that this will have the desired effect of
overriding the power name on the pin. Alternatively, it might cause
you to interconnect all your power buses, but I don't think it does
that.

The bad thing about this is that many of the Orcad parts have zero
length pins for the power pins, and the pins may not be located on the
part body where you would like to see them. I suppose that this is
because they forgot that someone might actually want to make these
pins visible. The work around, of course, is to make your own library
of parts on which you want sane power pins. This is what I usually do.

--
NOTE: to reply, remove all punctuation from email name field

Ned Forrester [email protected] 508-289-2226
Applied Ocean Physics and Engineering Dept.
Oceanographic Systems Lab http://adcp.whoi.edu/
Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
 
C

Charles Edmondson

Jan 1, 1970
0
Malcolm said:
Hi,

I can't seem to find a good way of having logic gates on different
rails.

My options seem to be:

Edit part to change power name for each part.
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?
Hi Malcolm,
You are using Capture, right? If so, you can just make the power pins
visible, and attach them to the different rails. That makes it pretty
apparent.

Of course, if you are using PSpice, only some of the parts have the
ability to use different power supply rails, spec. only the CMOS based
parts usually have the option...
 
M

Malcolm Reeves

Jan 1, 1970
0
Rubbish :)
Hidden power pins are a complete PITA to a service tech. When you come to
service the product, the circuit MUST show which supply each chip is connected
to. And preferably on the chip not in some hand-typed table...
Geo

Thanks to all for their suggestions but let me address this point.

I would agree that hidden power pins are a pain, but then so is power
pins on all 6 gates. The best method I have seen is where a part has
6 gates and a power block. That way you can put the power block on a
decoupling sheet. The information is all there but the power pins
don't clutter up the logic as normally you don't care about the rails
(i.e. if they are all VCC).

In my circuit I have opted for editing the gate to two different
parts. One with the label VCCa connecting to VCCa and one VCCb. That
way I can pick the appropriate part for the right rail and annotate
won't assign the wrong gate to the wrong package. The labels are
shown in on each part of course.

The alternative of power pins visible I'd have to do for all gates to
ensure they all packaged right. Since I only have two ICs my method
seems more tidy.


--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
([email protected], [email protected] or [email protected]).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - www.CharteredConsultant.co.uk - The Consultant A-List
 
J

Jim Thompson

Jan 1, 1970
0
Hi,

I can't seem to find a good way of having logic gates on different
rails.

My options seem to be:

Edit part to change power name for each part.
Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?

Malcolm, Here is the way I do it with my individual logic parts
within I/Cs...

Mylib.slb : INVERTER

Pin Data
U? VP
X Y E R C# Name invert_a

VN 0 20 i 1 A
50 20 o 2 Y
30 0 x 3 VP
30 40 x 4 VN
Symbol Data:

Description = Inverter
Type = p
Bbox = (0 0) (50 40)
Origin = (0 20)

Attributes

PART = INVERTER
REFDES = U?
TEMPLATE = X^@REFDES %A %Y ?GLOPWR|[email protected] [email protected]|%VP %VN|@MODEL
MODEL = invert_a
GLOPWR =
VPLUS = PWRP
VNEG = PWRN

This is, of course, with Schematics, not Capture, which you seem to
have switched to ;-)

...Jim Thompson
 
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