AR# 68571


2015.4 Vivado - Phys_opt_design inverts ENBWREN of RAMB36E1 connection, causing BRAM function error.


I see that the ENBWREN pin of an RAMB36E1 has had its connectivity changed by phys_opt_design, causing the BRAM to have a functional error.

How can I resolve this issue?


This issue is resolved in Vivado 2016.3. For Vivado versions prior to 2016.3, one of the following work-arounds can be used:

1) Add the following to the Tcl script of the tcl.pre option of phys_opt_design:

set_param physynth.bramEnableOpt 0

2) Add DONT_TOUCH constraints on the affected BRAMs:

For example:

set_property DONT_TOUCH true [get_cells RAM_INSTANCE_NAME]

The attached script can be used to detect whether there is an issue in an existing design. 

To use it, just source it on the DCP after phys_opt_design.


Associated Attachments

Name File Size File Type
bram_physopt_detect.tcl 506 Bytes TCL
AR# 68571
Date 01/24/2017
Status Active
Type General Article
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