Xilinx Constraints Guide

TSidentifier (Timing Specification Identifier)
Architecture Support
Applicable Elements
Chapter 4: Xilinx Constraints
TSidentifier (Timing Specification Identifier) is a basic timing constraint. TSidentifier
properties beginning with the letters TS are used with the TIMESPEC in a User
Constraints File (UCF). The value of TSidentifier corresponds to a specific timing
specification that can then be applied to paths in the design.
Applies to all FPGA devices and all CPLD devices.
TIMESPEC keywords
Propagation Rules
It is illegal to attach TSidentifier to a net, signal, or design element.
Syntax Examples
The following examples show how to use this constraint with particular tools or
methods. If a tool or method is not listed, you cannot use this constraint with it.
UCF and NCF Syntax
All the following syntax definitions use a space as a separator. The use of a colon as
a separator is optional.
Defining a Maximum Allowable Delay
TIMESPEC “TSidentifier”=FROM “source_group” TO “dest_group” allowable_delay [units];
Defining Intermediate Points (UCF)
TIMESPEC “TSidentifier”=FROM “source_group” THRU “thru_point” [THRU
“thru_point1”... “thru_pointn”] TO “dest_group” allowable_delay [units];
where
• identifier is an ASCII string made up of the characters A-Z, a-z, 0-9, and _
• source_group and dest_group are user-defined or predefined groups
• thru_point is an intermediate point used to qualify the path, defined using a
TPTHRU constraint
• allowable_delay is the timing requirement value
• units is an optional field to indicate the units for the allowable delay. The default
units are nanoseconds (ns), but the timing number can be followed by ps, ns, micro,
ms, GHz, MHz, or kHz to indicate the intended units.
Defining a Linked Specification
This allows you to link the timing number used in one specification to another
specification.
TIMESPEC “TSidentifier”=FROM “source_group” TO “dest_group” another_TSid [/ |
*] number;
Constraints Guide
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