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AR# 2259

1.5i NGD2VER, NGD2VHDL - Prorating simulation


Keywords: temperature, voltage, ucf, back annotation, timing simulation

Urgency: Standard

General description:
How do you prorate simulation?


Prorating is a linear scaling operation on existing speed file
delays and is applied globally to all delays. The prorating
constraints, VOLTAGE and TEMPERATURE, provide a
method for determining timing delay characteristics based
on known environmental parameters.

The VOLTAGE constraint provides a means of prorating
delay characteristics based on the specified voltage. The
UCF syntax is as follows:


Where value is an integer or real number specifying the
voltage and units is an optional parameter specifying the
unit of measure.

The TEMPERATURE provides a means of prorating device
delay characteristics based on the specified junction
temperature. The UCF syntax is as follows:

TEMPERATURE=value[C | F | K];

Where value is an integer or a real number specifying the
temperature. C, K, and F are the temperature units: F is
degrees Fahrenheit, K is degrees Kelvin, and C is degrees
Celsius, the default.

Each architecture has its own specific range of valid operating
temperatures and voltages. If the entered temperature or voltage
does not fall within the supported range, the constraint is ignored
and an architecture-specific default value is used instead.

For simulation, the VOLTAGE and TEMPERATURE constraints
will be processed from the UCF file into the PCF file.

ngdanno -p design.pcf design.ncd

For VHDL, enter the following:
ngd2vhdl [options] design.nga

For Verilog, enter the following:
ngd2ver [options] design.nga

Do not combine both minimum timing and prorating (-s and -p)
as minimum values would override prorating. Please see
(Xilinx Solution 4422) on details regarding using mindelays for

Prorating may only be available for select FPGA families, and it
is not intended for military and industrial ranges. It is applicable
only within the commercial ranges.
AR# 2259
Date 07/31/2001
Status Archive
Type ??????