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AR# 34088

ISE 11.3 NGDBuild - "WARNING:ConstraintSystem:119..." on HBLKNM attribute

Description

I receive the following warnings in Translate with the Asynchronous Input Synchronization coding example from the ISE 11.1 Language Template:

WARNING:ConstraintSystem:119 - Constraint <NET: UniqueName:
   /top/EXPANDED/sync_SYNC_signal\/sreg<1> HBLKNM = "sync_reg">: This constraint
   cannot be distributed from the design objects matching 'NET: UniqueName:
   /top/EXPANDED/sync_SYNC_signal\/sreg<1>' because those design objects do not
   contain or drive any instances of the correct type.

WARNING:ConstraintSystem:119 - Constraint <NET: UniqueName:
   /top/EXPANDED/sync_SYNC_signal\/sreg<0> HBLKNM = "sync_reg">: This constraint
   cannot be distributed from the design objects matching 'NET: UniqueName:
   /top/EXPANDED/sync_SYNC_signal\/sreg<0>' because those design objects do not
   contain or drive any instances of the correct type.

What does this warning mean, and how can I avoid it?

Solution

The warning states that the HBLKNM attribute cannot be propagated to valid applicable elements.

In the coding example, HBLKNM is expected to propagate to registers.

signal sreg : std_logic_vector(1 downto 0);
attribute HBLKNM of sreg : signal is "sync_reg";

The problem is that when attached to a NET, HBLKNM is only propagated to PADs.

It is not explicitly stated in the ISE 10.1 Constraints Guide but has been added in the 11.1 documentation.

To eliminate the warning, place HBLKNM constraints on desired register instances.

AR# 34088
Date Created 01/08/2010
Last Updated 01/13/2015
Status Active
Type Error Message
Tools
  • ISE Design Suite