Xilinx ISE, where do the pins go?

Nov 01, 2006 1 Replies

Hi, it seems obvious, but I'll ask the question anyways to be sure.



My dual port ram on a Spartan 3 does not use the rst or ena inputs, nor have but one clock (clka). On the schematic view, it shows these pins going nowhere. Can I assume this is "shorthand" for "goes to pullup"? The documentation on the embedded rams says that pullup of unused inputs is recommended, because "it takes no routed resources", vs. zero driven inputs. This implies there is a special bit to pull up right at the input. Does the unconnected pin on the schematic represent this?



Thanks,



Scott Moore


No, if a pin is pulled up, it will have a pullup circuit in the schematic, which you can add. The schematic is saying that the pin isn't connected which what that means may well be device dependent.

---Matthew Hicks

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