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AR# 62834

2014.4 Vivado - LUT equation box displays incorrect value when the LUT4's INIT value is 16'hABFB

Description

 In Vivado or PlanAhead, when I open the LUT equation box for a LUT4 with INIT value =  16'hABFB, it shows "O=I0".

The truth table in the cell properties correctly shows the output values but the equation (O=I0) for the output does not match the truth table.

In the first line of the truth table,  "0000" (O= 1) <> (I0 = 0).

LUT_truth_table.png

Solution

The correct value that should be shown in the LUT equation box is "O = (I0 + (I2 * !I3) + (!I1 * !I2))".

This is only a display issue and will not affect LUT4's logic function.

This issue is fixed in the 2015.1 release of Vivado Design Suite.

AR# 62834
Date Created 11/13/2014
Last Updated 11/24/2014
Status Active
Type General Article
Tools
  • Vivado Design Suite - 2014.3