AR #33122 - 11.2 System Generator for DSP - Why does the Multiplier block use fabric when I specified "use embedded multipliers"?

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11.2 System Generator for DSP - Why does the Multiplier block use fabric when I specified "use embedded multipliers"?

AR#	33122
Part	SW-SysGen
Last Modified	2009-07-10 00:00:00.0
Status	Active
Keywords	spartan-3, DSP, sysgen

Description

Keywords: spartan-3, DSP, sysgen

When I generate my design I notice that the multiplier blocks are setting "use_LUTs" during core generation even though "use embedded multipliers" is specified in the System Generator GUI.

Solution

This is due to a known issue in System Generator. This issue seems to only affect devices which have 18x18 dedicated multiplier slices but not DSP48 slices.

To work around this issue, check the box for "Use behavioral HDL" on the Implementation tab. This will produce code which will be inferred to use the embedded multiplier blocks by the synthesis tool.

This issue will be addressed in a future release of System Generator.