Specifications

Schematic Simulation Issues 79
NOTE: Although it may be tempting to set all pins to “bidirectional,” this is not
recommended. It significantly increases simulation overhead and
increases the difficulty of isolating circuit drive problems.
Port Connector Pin Type
The pin type on the port connector is also used to translate the value of any
incoming signal changes, in a manner similar to the parent pin type. Nor-
mally, the pin type setting on a port connector should complement the set-
ting of the parent pin, as follows:
Other settings on the port connector pin are not recommended.
Pin Type Effect
Input This will prevent that pin from ever driving the attached
signal, regardless of drives in the internal circuit.
Output / Three–state This will pass the sum of the internal drives up to the parent
pin without any translation. Signal value changes on the
signal attached to the parent pin will not be passed to the
internal circuit.
Open collector / Open
emitter
Any drive level from the internal circuit will be translated
according the capability of the pin type. See Appendix B,
Device Pin Types, for more details.
Bidirectional All changes on the internal signal are passed to the parent
pin and vice versa.
Other types Other types, such as Tied High and Tied Low, are not
recommended.
Parent Pin Type Port Connector Name Port Connector Pin Type
Input Port In Output
Bidirectional Port Bidir Bidirectional
All others Port Out Input
LW Reference.bk Page 79 Monday, December 15, 2003 5:59 PM