OPNDRN Primitive

The OPNDRN primitive is similar to a TRI primitive, with a single input and a single output. An OPNDRN primitive fed by a signal called my_signal is equivalent to a TRI primitive whose output enable input is fed by the complement of my_signal, and whose primary input is fed by a GND primitive.

If the input to the OPNDRN primitive is low, the output will be low. If the input is high, the output will be a high-impedance logic level.

When you use an OPNDRN buffer, you must observe the following rules in addition to the rules listed in Primitive/Port Interconnections:

Note: For information about Quartus® Prime Standard Edition primitive instantiation, go to Using a Quartus® Prime Standard Edition Logic Function.
Related reference

TRI Primitive
GND (Block Design Files only) Primitive
Primitive/Port Interconnections
BIDIR or INOUT Primitive/Port

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