Specifications

54 Chapter 3—Advanced Schematic Editing
IMPORTANT: If you create a port connector symbol using the device symbol editor, the pin type
(input, output or bidirectional) must be set carefully for each pin on the port
connector. The pin on the Port Connector symbol must be of the opposite type to
the corresponding pin on the parent device symbol. For example, a signal coming
in to the subcircuit is actually an output from the port connector pin.
Note, for example, that the pin on the Port In device in the connect.clf library is set
to be an output and the Port Out device has an input pin. A bidirectional port has
bidirectional pins on both sides of the interface.
Bus Ports
Connections can be made between busses across circuit levels using Bus
Port Connectors. Bus pins on a parent device symbol must be matched with
a Bus Port Connector having identical internal pins. For this reason, Bus
Port Connectors must always be custom–made using the device symbol
editor.
Bus Pin Name Matching
Note the following rules for name matching in bus ports:
 As with other Port Connectors, a Bus Port Connector must be given a
name exactly matching the pin name of the bus pin on the parent
device.
 The internal pins in the parent bus pin must exactly match the internal
pins on the Bus Port Connectors bus pin.
 The pin name of the bus pin itself on the Bus Port Connector is not
significant.
 As with normal ports, the names of the signals attached to the Bus Port
Connector’s pin are not significant.
Bus Pin Example
For example, the following simple device has a bus pin called CONTROL
containing internal pins CLK, MEMW/, and MEMR/.
LW Reference.bk Page 54 Monday, December 15, 2003 5:59 PM