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AR# 2243

M1.3/M1.4/M1.5 CPLD: Fitter takes more than 200 Megs of RAM while fitting a design

Description

Keywords: cpld, fitter, ram, memory, 95216, 95288, timespecs

Urgency: standard

General Description:

CPLD fitter may require more than 200 Megs of RAM while trying
to fit a design in a larger device such as 95216 or 95288.

The underlying cause could be the user's UCF file, if it
contains a lot of global timespecs which cause the fitter to
trace a large number of paths, greater than 100,000 in some
cases.

Solution

1

Use more specific Timespecs in your file as recommended by
Xilinx.

Example -

Instead of using a global timespec such as

TIMESPEC TS01 = FROM:FFS:TO:PADS:25ns;

use

TIMESPEC TS01 = FROM:Flip_Flop_1:TO:Pad_1:25ns;

2

Turn off the Timespecs during the Fitting.
AR# 2243
Date Created 06/07/1997
Last Updated 03/26/2000
Status Archive
Type General Article