Spectrum Software
Industrial Strength Simulation




Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.




Creating Parts with Many Pins


Suppose you have to create a part with a great many pins. How do you do that? The usual method is to create a suitable shape with the Shape editor using the Block shape. It looks like this:

16 pin block shape

When the part is created in the Component editor, you use the created block shape and manually assign the pins and their names one by one. This works well up to a point, but what if you have a part with hundreds of pins? The process can be error prone with so many pins.

With the release of MC11.0.0.9, you now have a new option. The new capability is implemented with two features:

The Shape editor creates a large block shape automatically by specifying only the number of pins, The pins are placed as equally as possible on either side of the block shape.

The Component editor's Add Part wizard now automatically assigns the pin names from the .subckt statement. The name assignment starts at the shape's origin point and assigns names sequentially in a counter-clockwise order. The first pin name in the .subckt statement is assigned to the pin nearest the shape origin. Then the next pin name in the subckt list is assigned to the second pin and so on until the last pin name is assigned. Even if you want the pins to be assigned in a different way, the process at least places the pins systematically with the correct names, so you can drag the pins to different locations.

Consider this subcircuit:

The Big150 subcircuit

This subcircuit, called BIG150, uses 150 pins as can be seen from its .subckt statement:

.subckt BIG150 D1 D2 D3 EA EB OA B 8 9 10 11 12 13 14 15 16 17 18 19 20
+ 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
+ 139 140 141 142 143 144 145 146 147 148 149 150

In this case some of the pins have names with letters, but most have numeric names. To illustrate, we'll create a suitable shape and then add the part in the Component editor. If you wish to follow along, you must copy the Big150.LIB from this newsletter's zip file to the Micro-Cap LIBRARY folder.

Select Windows Menu / Shape Editor... Click on the Add button. A dialog box will come up and ask for the shape name. Enter Big150. Select the Block icon. Click on the Origin symbol in the shape area. A dialog box will come up and ask for the number of pins. Enter 150. The screen should now look like this:

The Big150 shape

Exit the Shape editor and select Windows menu / Component Editor. Select a place in the part hierarchy by clicking on one of the groups , like Analog Library. Click on the Add Part wizard.

Select Subckt from the first panel.

Click on the Next button or press Enter.

Enter Big150.lib. Click on the Next button or press Enter.

Click on the Big150 part name.

Click on the Next button or press Enter.

Click in the Shape list and press 'B' until you see the 'Big150' shape created earlier.

Press Enter five more times to complete the wizard. Your screen should now look like this:

The Big150 part

At this scale it is hard to see the pin names. Click on the Magnifying icon several times to the enlarge the shape and you see this:

The Big150 part enlarged

You can see the first few pin names imported from the subckt statement in the Big150.lib file. Exit from the Component editor by clicking on the X in the upper right corner of the dialog box.

Now we can create a circuit using the Big150 part. Press CTRL + N to create a new circuit file. Click on the Component menu / Find Component and type in Big150 in the name field and press Enter. This selects the Big150 part. Click in the upper left of the circuit. Click the Show check box next to the Big150 part name. Click on the Pin Names check box. Click OK in the Attribute dialog box or just press Enter. This will place the Big150 part. Press the Spacebar key to toggle from Add Part mode to Select mode, and the drag the 'X1' name and the 'Big150' name roughly center then in the block shape.

Your circuit should now look like this:

The Big150 part placed in a circuit.

When you request an analysis, the program reads the Big150.lib to fill in the content of the Big150 part. Of course, there is still much to do in the circuit; setting up sources to drive the inputs and circuitry to load the outputs, but a great deal of the work is done.

Micro-Cap 12 will have a more sophisticated version of this, allowing for 1- 4 sides with varying pin spacing, pin length, and pin alignment, but the basic capability will be similar.

Download Winter 2015 Circuit Files
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