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AR# 60340

2014.2 Vivado - MULT18X18S instantiated in my design but when retargeted in Vivado it appears to be incorrect

Description

I have a design from ISE 13.x or earlier which contains HDL code instantiating a MULT18X18S primitive.

If I import this code into Vivado, This multiplier is retargeted correctly to a DSP48E1 primitive.

However, the MREG attribute of this DSP48E1 is set to "0" incorrectly, this should be "1".

Solution

This issue will be fixed in the Vivado 2014.3 release.

There are two workarounds available for earlier releases:

  • Use an NGC file from ISE and XST as an input source to Vivado for the given code.  

    ISE 14.7 correctly converts the  MULT18X18S primitive to a DSP48E1 with the MREG attribute set to "1".

  • Instantiate the DSP48E1 directly with the MREG set.


AR# 60340
Date Created 04/18/2014
Last Updated 06/20/2014
Status Active
Type General Article
Tools
  • Vivado Design Suite - 2013.4
  • Vivado Design Suite - 2014.1