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module test1 (input data, oe, output out, inout bidir); wire triwire, gnd; assign gnd = 1'b0; assign triwire = oe ? gnd : 1'bz; and(out, triwire, data); assign bidir = triwire; endmoduleIn the design, the open-drain buffer triwire feeds an AND gate in addition to feeding the pin bidir. As a result, the Quartus Prime software converts its fanout to the AND gate to a wire, and gives this warning. Note that an inversion is also an internal fanout. If an open-drain buffer feeds a pin through an inversion, the Quartus Prime software will convert the open-drain buffer into a wire. Additionally, if an open-drain buffer feeds another open-drain buffer, the Quartus Prime software will convert the first open-drain buffer to a wire.
ACTION: Avoid this warning message by removing all the internal fanouts of the open-drain buffer.
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