This dialog leads you through the process of creating a Sub Net. A Sub Net is a group of pins which are part of a larger net. By defining a Sub Net, you can apply rules to the pads and the connections between them. A Sub Net is defined by a pad attribute which is common to those pins. The Create Sub Net dialog enables you to nominate the pins as well as define and add the attribute to them in one step.
Shortcuts
Menu: Setup
Default Keys: T
Command: Technology
Locating this option
Available from: Setup menu > Technology option > Sub Net tab > New button > Create Sub Net dialog
Available from: Design > Interactive pad selection Context menu > Create Sub Net option
Navigation
Use Filter
Each of the Use Filter boxes will enable you to filter the relevant list.
Dim Design To Show Sub Net
Select this check box to dim the design to show the Sub Net being selected. This makes it easier to tell that you are selecting the right items. It is also possible to select pins in the design rather than selecting them in the appropriate list.
Creating A Sub Net
There are three methods of creating a Sub Net.
Choose Pins In Net
Use this if you know which pins you want and a suitable attribute does not exist on these pins already. Use the Nets list to select a net, you can filter this list by pressing the Use Filter button. The Component Pins on the selected net are shown in the next list. Select the pins you want in the sub net. A filter is available for this list.
Press Add Sub Net To List to add the Sub Net to the lower list.
Use Existing Pin Attribute
Use this if the attribute already exists on the pins. (This might be because you have already used the Attribute Editor or they were imported through some other source). This changes the dialog to display a list of nets that have an existing pin attribute. Select the attribute and a list of the pins with that attribute (which may be on more than one net).
Press Add Sub Net To List to add the Sub Net to the lower list.
Just Add Sub Net Entry
You do not select any pins at this stage, you can do that later using the Attribute Editor for example.
Press Add Sub Net To List to add the Sub Net to the lower list.
Just Add Sub Net Entry is used to create an empty sub net entry that you will add the pin attributes to later on. You can add these interactively or by using the Attribute Editor in the design. With this selected the net and pin attribute selections are not available.
Add Sub Net To List
When the button Add Sub Net To List is pressed, the selected Sub Net will appear in the lower grid and the Create box selected.
Pads in the Sub Net
This part of the dialog shows you the pins in the sub net selected in the list of Possible Sub Nets. Here you can Add or Remove pins, and also change their order. This order defines the order the attribute values are allocated, this is important if you are using Connect In Pin Order.
Sub Net Attribute Name & Match Value
The name of the defining attribute is shown in this column. It may be a generated name, so you may wish to edit it here.
The Match Value will normally be the wildcard value *, but any wildcard value is valid and will restrict the pins to those with a matching attribute, this is useful if the attribute has been added through some other mechanism (such as an imported value).
Connect In Pin Order
Connect in Pin Order forces the connection pattern to be defined by the attribute values on the pins. (Also known as daisy chain routing).
The connection order is defined by an alphanumeric comparison of the sub net pin attribute values. The connections between the pins should form a chain or tree, such that each pin forms a link between pins with lower values and those with higher values.
Create the Sub Nets
Once you have selected some sub nets to create. Press OK to take you back to the Technology dialog, Sub Nets page.
Related Topics
Technology Overview | Technology - Sub Nets | Technology - Attribute Names