Honored ContributorHello,
I have noticed a warning in the fitter that the bidirectional pins I am connecting to the DQ lines for the SSRAM aboard the Cyclone III starter kit have permanently disabled output enable. How do I change this parameter for the bidir pins? Thanks.
Honored ContributorPermanently disabled means the OE = GND (if active high) or VCC (if active low). I can never remember which. In any case, the I/O driver is always disabled, making it a bidir pin that's basically just an input. Did you give it a non-Z driver in your design?
Honored ContributorI'd like to agree to HDL Guru. It an I/O pin is permanentely disabled than that's not a problem of the pin but of the logic that drives the enable line.
Honored ContributorHello,
Thanks for the replies. I am not entirely sure what you mean by non-Z driver. I have the bidirectional lines connected to a Tri-state buffer controlling input to the bidr lines. However, I have somehow corrected these warnings without noticing what I did to change things. Thanks for the help. AndreHonored ContributorNon-Z driver simply means that a signal is send to the output. In VHDL or Verilog designs, driving an output to 'Z' state is equivalent to disabling the output driver. It's the ususal technique to infer a tristate driver in HDL.
I understand that you have an tristate driver connected to the pin, either in schematic entry or as explicite instantation of a tristate primitive in HDL. In this case, the error means that the output enable of the tristate driver is never activated cause no respective logic exists in your design. This may be, cause your design is yet incomplete or the logic doesn't correspondend to the intended function.
