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AR# 22128

8.1i Virtex-4 PAR - "ERROR:Place:472 on ECC RAM with Shared Address lines"


I am using two RAMB32_S64_ECC components to create a 512x128 Dual-port Memory with ECC. My design fails during placement and reports the following error:

"ERROR:Place:472 - Placer was unable to create RAMB16 ECC mode cascade related RPM forcomponent ECC0/RAMB16_LOWER. The design would not be routable.

The reason for this issue:

The structured logic has to be merged with another RPM which causes a placement violation for component ECC1/RAMB16_LOWER. The following components are part of this structure:




The placement failure occurs because the placer incorrectly constructs an RPM macro for the RAM. This issue will be fixed in version 9.1i.

Meanwhile, you can work around this problem by inverting one bit of the addresses:

assign rdaddr_u= {~RDADDR[8], RDADDR[7:0]};

assign wraddr_u = {~WRADDR[8], WRADDR[7:0]};

AR# 22128
Date 12/15/2012
Status Active
Type General Article