Cyclone V differential HSSI REFCLK implementation

I tried your suggestion and removed the ALTIOBUF and directly used the refclk non-inverted pin, but I still get the same error.

Error (177035): The input pin adc_dco_p assigned to HSSI Pin_AA11 has no fanout.

I found the following information at quartushelp.altera.com:

[h=3]<direction> pin <name> assigned to HSSI <name> has no <fanin_or_fanout>.[/h]

(ID: 177035)

CAUSE:

The specified pin is assigned to an HSSI input/output and has no fan-out (http://www.alteraforum.com/reference/glossary/def_fan.htm) and fan-in. HSSI input/output must be connected with exception of reserved refclk pins.

ACTION:

Remove the specified pin, location assignment, or both. Or if it is refclk, set as reserved

How do I set the refclk pins to reserved?

Thanks.

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You don't need altiobuf, and I guess, it doesn't work for dedicated clock signals at all.

Just assign the non-inverted input pin and specify a differential IO-standard supported by the pins.

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