Specifications

56 Chapter 3—Advanced Schematic Editing
to be used because the default primitive type for a symbol is
SUBCCT.) Save the symbol in a library.
 Use the symbol as desired in your schematic.
 Use the New Design command to create a new and completely
independent design. Create the schematic for the subcircuit in this
design. You may use any existing parts from libraries except the parent
symbol that we created above. Subcircuits cannot be recursive!
 Add port connectors to the design and attach them to the appropriate
connection points. Each port connector must match its corresponding
pin in type according to the following table:
:
*
For Tied High, No Connect, and other pin types, use a Port In for
consistency, although no simulation data is transferred through these
types of pins in any case.
 Name each port connector to match the associated parent pin. You may
want to have the parent symbol open in the device symbol editor at the
same time so that the names are easily checked.
NOTE: There must be a one–to–one match between the pins on the parent symbol
and the port connectors in the subcircuit.
 Return to the design where the parent symbol was used. Select the
parent symbol by clicking on it. If it has been used more than once,
select any of the copies.
 Select the Attach Sub-Circuit command from the Schematic menu.
Choose the design containing the subcircuit from the list of open
Parent Pin Type Port Connector (in the connect.clf library)
Input Port In
Output Port Out
Bidirectional Port Bidir
Bus Must be custom–made
All others
*
Port In
*
LW Reference.bk Page 56 Monday, December 15, 2003 5:59 PM