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AR# 3332

M1.3/1.4 TRACE: A DPRAM DPO to destination FROM:TO constraint is not analyzed

Description

Keywords: Dual Port Ram, TIG, constraints, DPO, SPO

Urgency: Hot

General Description:

A TNM attached to a DPRAM may not attach itself correctly
to the RAM if the SPO output is not connected. For example,
for the following path:

|--------|
| DPRAM |
| spo|---x
| | |----|
| dpo|-----------------|D Q|
| | |> |
|--------| |----|
tnm=myram tnm=myflop

This path would be picked up by a PERIOD constraint. However,
a constraint such as "TIMESPEC TS_IG=FROM:myram:TO:myflop:TIG;"
will not be recognized (path still in PERIOD constraint ).
Even if the constraint is not a TIG ( a normal FROM:TO, for
instance), it will still not be recognized (PERIOD will still
control it).

Solution

This is actually a MAP bug, and it is fixed in a M1.4 patch
on the FTP site. Go to: http://www.xilinx.com/txpatches/pub/swhelp/M1.4_alliance
and download the appropriate "core" patch for your platform.

AR# 3332
Date Created 01/23/1998
Last Updated 03/27/2000
Status Archive
Type General Article