Differential Pair Net Unconnected To Differerential Pair Pin

This compiler hint appears when a differential pair net is not connected to a differential pair pin of a physical device. The message is displayed in the Messages panel in the following format:

Net NetName of differential pair PairName is not connected to a differential pair pin,

where

NetName is the name of the positive or negative polarity net in the pair (e.g. V_RX1_N or V_RX1_P)

PairName is the name of the differential pair (e.g. V_RX1).

Default Report Mode

Error

Recommendation

A true differential pair pin is hard-wired for a physical device (e.g. a Xilinx Virtex-II Pro FPGA device). Although such a pin may appear with the identifier N (for negative) or P (for positive) as part of its name, you cannot make a pin differential simply by changing its name.

Use the Compile Errors dialog to quickly cross probe to the pin to which the differential pair net is currently connected. Consider the following when resolving a violation of this type:

• If the net is correct but has simply been attached/wired to the wrong pin of the device, determine the correct pin and move the net label accordingly.
• If the net has been erroneously specified as a differential pair net, change the associated net label to the correct (non-differential) naming and remove the attached differential pair directive from the connecting wire.
• If the pin is, in fact, not to be used at all in the design, ensure that net label, wire and differential pair directive are removed and place a No ERC marker on it.