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AR# 15842

7.1i XST - "ERROR:Xst:1490 - The instantiated LUT4 <lut_name> does not have any INIT property in unit <unit_name>"

Description

Keywords: EQN

Urgency: Standard

General Description:
When the EQN attribute is used to define a LUT, XST reports the following error:

"ERROR:Xst:1490 - The instantiated LUT4 <Uor4> does not have any INIT property in unit <MULTS_4>."

Solution

To work around this problem, add an empty INIT attribute as follows:

For Verilog, use:
============
// synthesis attribute INIT of Uor4 is "xxxx";

where "xxxx" is the INIT value that captures the intended equation.

For VHDL, use:
=============
attribute INIT : string;
attribute INIT of Uor4 : label is "xxxx";

where "xxxx" is the INIT value that captures the intended equation.

To XST, it will appear that an INIT has been applied. (XST will later discard the dummy INIT value.)

The following warning will be reported, but you can safely ignore it:

"WARNING:Xst:616 - Invalid property "INIT ": Did not attach to U_mult_mult_0_Uor4."
AR# 15842
Date Created 09/03/2007
Last Updated 01/06/2009
Status Archive
Type General Article