DCI on Virtex 5

[cksim1972]

I would like to use the DCI feature in Virtex 5 for a few signals.

I have configured those pins to be LVDCI_33 in the ucf file and I have the reference resistors on VRP and VRN.

However, the DCI does not seem to be working.

Is there any implementation steps or code that need to be added into the design ?

 Thank you.

[prateek_bhatt]

Hello.

How did you come to a conclusion that DCI is not working?? 

[cksim1972]

Hi,

I make some changes to the value of the resistors on VRN and VRP, but did not observe any difference in the output (it is used as a clock output pin).

That is why I suspect the DCI is not functioning (or activated).

As this is the first time I am using the DCI feature and I could not find any detailed implementation info, I could only trial and error.

Hence, I really hope that someone with experience on this could advise on the steps needed to ensure the DCI is activated.

Thank you.

[evgenis1]

You can open the PAD report (your_design_name_pad.csv) and check that those pins are indeed LVDCI_33.

OutputLogic 

[cksim1972]

Hi,

Yes, the pad report does show that the pin is LVDCI_33.

I noted that there is a column "DCI Value". It is blank. Is this correct ?

Thank you.

[evgenis1]

It refers to DCI_VALUE constraint (see Constraints Guide doc). If not set, it has a default value.

OutputLogic 

[cksim1972]

Hi,

Questions on items I have found so far.

Is there a need to instantiate/use the  "DCI Reset" block (the one with a "LOCKED" output) ?

Also, I noted some possible configurations for DCI, e.g. continuous matching mode, etc. Is there a need to select any of such configurations ?

Really appreciate your above replies.

Thank you.

[evgenis1]

I don't think so. DCI is an IOB property defined as a constraint in UCF.

 OutputLogic