Xilinx Synthesis Technology User Guide

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XST User Guide • From-To FROM-TO defines a timing constraint between two groups. A group can be user-defined or predefined (FFS, PADS, RAMS). See the “FROM-TO” section in the Constraints Guide for details. Example: XCF Syntax: TIMESPEC “TSname”=FROM “group1” TO “group2” value; • TNM TNM is a basic grouping constraint. Use TNM (Timing Name) to identify the elements that make up a group which you can then use in a timing specification. TNM tags specific FFS, RAMs, LATCHES, PADS, BRAMS_PORTA, BRAMS_PORTB, CPUS, HSIOS, and MULTS as members of a group to simplify the application of timing specifications to the group. The RISING and FALLING keywords may also be used with TNMs. See the “TNM” section in the Constraints Guide for details. XCF Syntax: {NET | PIN} “net_or_pin_name” TNM=[predefined_group:] identifier; • TNM Net TNM_NET is essentially equivalent to TNM on a net except for input pad nets. (Special rules apply when using TNM_NET with the PERIOD constraint for Virtex/-E/-II/-II Pro DLL/DCMs. See the “PERIOD Specifications on CLKDLLs and DCMs” section in the Constraints Guide.) A TNM_NET is a property that you normally use in conjunction with an HDL design to tag a specific net. All downstream synchronous elements and pads tagged with the TNM_NET identifier are considered a group. See the “TNM” section in the Constraints Guide for details. XCF Syntax: NET “netname” TNM_NET=[predefined_group:] identifier; 5-32 Xilinx Development System
Design Constraints • TIMEGRP TIMEGRP is a basic grouping constraint. In addition to naming groups using the TNM identifier, you can also define groups in terms of other groups. You can create a group that is a combination of existing groups by defining a TIMEGRP constraint. You can place TIMEGRP constraints in a constraints file (XCF or NCF). You can use TIMEGRP attributes to create groups using the following methods. ♦ Combining multiple groups into one ♦ Defining flip-flop subgroups by clock sense See the “TIMEGRP” section in the Constraints Guide for details. XCF Syntax: TIMEGRP “newgroup”=”existing_grp1” “existing_grp2” [“existing_grp3” . . .]; • TIG The TIG constraint causes all paths going through a specific net to be ignored for timing analyses and optimization purposes. This constraint can be applied to the name of the signal affected. See the “TIG” section in the Constraints Guide for details. XCF Syntax: NET “net_name” TIG; Old Timing Constraint Support In the past, XST supported limited private timing constraints. These constraints will be supported in current release, and the next, in the same way they were supported in release 4.2i without any further enhancements. Xilinx strongly suggests that you use the newer XCF syntax constraint style for new devices. The following is a list of these old private timing constraints: XST User Guide 5-33
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Xilinx Synthesis Technology (XST) U
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About This Manual Manual Contents T
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Resource Description/URL About This
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Conventions Typographical This manu
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Contents About This Manual Conventi
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Contents 8-bit Shift-Left Register
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Contents Dividers .................
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Contents Verilog Flow: ............
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Contents Sequential Process with a
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Introduction Architecture Support X
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Introduction 4. Set the desired Syn
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Figure 1-1 View Synthesis Report In
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HDL Coding Techniques This chapter
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HDL Coding Techniques The following
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Table 2-1 VHDL and Verilog Examples
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Signed/Unsigned Support Registers H
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Flip-flop with Positive-Edge Clock
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VHDL Code HDL Coding Techniques Fol
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IO Pins Description CE Clock Enable
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Log File HDL Coding Techniques The
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HDL Coding Techniques Verilog Code
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HDL Coding Techniques 4-bit Latch w
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Tristates Log File HDL Coding Techn
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Counters HDL Coding Techniques XST
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HDL Coding Techniques 4-bit Unsigne
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HDL Coding Techniques entity counte
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Verilog Code HDL Coding Techniques
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HDL Coding Techniques 4-bit Unsigne
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Accumulators HDL Coding Techniques
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HDL Coding Techniques • shift mod
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HDL Coding Techniques 8-bit Shift-L
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Dynamic Shift Register module shift
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library IEEE; use IEEE.std_logic_11
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neither Full nor Parallel module no
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Related Constraints Related constra
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HDL Coding Techniques entity mux is
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Decoders Log File HDL Coding Techni
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VHDL (One-Cold) Following is the VH
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VHDL Following is the VHDL code. li
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Priority Encoders Log File HDL Codi
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Verilog Logical Shifters HDL Coding
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Example 1 HDL Coding Techniques The
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Verilog Arithmetic Operations Follo
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Unsigned 8-bit Adder HDL Coding Tec
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HDL Coding Techniques Verilog Follo
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Simple Signed 8-bit Adder HDL Codin
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Unsigned 8-bit Adder/Subtractor HDL
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Comparators (=, /=,=) HDL Coding Te
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HDL Coding Techniques this, XST can
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Dividers HDL Coding Techniques VHDL
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B C A OPER +/- RES OPER X8984 HDL C
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HDL Coding Techniques • RAM descr
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HDL Coding Techniques entity raminf
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HDL Coding Techniques VHDL The foll
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HDL Coding Techniques Verilog The f
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HDL Coding Techniques VHDL The foll
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VHDL Following is the VHDL code for
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HDL Coding Techniques Single-Port R
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Verilog HDL Coding Techniques Follo
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HDL Coding Techniques Single-Port R
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Verilog Following is the Verilog co
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VHDL HDL Coding Techniques Followin
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Dual-Port RAM with Asynchronous Rea
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HDL Coding Techniques Dual-Port RAM
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HDL Coding Techniques architecture
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HDL Coding Techniques Dual-Port RAM
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VHDL Following is the VHDL code for
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Inputs Next State Function RESET CL
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FSM with 1 Process HDL Coding Techn
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Inputs FSM with 2 Processes HDL Cod
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process2 : process (state, x1) begi
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State Registers HDL Coding Techniqu
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Compact HDL Coding Techniques Compa
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Black Box Support Log File HDL Codi
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FPGA Optimization Introduction This
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Macro Generation • Number of Cloc
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Multiplexers FPGA Optimization For
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RAMs FPGA Optimization Two types of
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Flip-Flop Retiming FPGA Optimizatio
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FPGA Optimization INCREMENTAL_SYNTH
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FPGA Optimization Note In the curre
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FPGA Optimization generated NGC fil
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FPGA Optimization The problem most
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Log File Analysis FPGA Optimization
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FPGA Optimization • Tristates Thi
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FPGA Optimization NOTE: THESE TIMIN
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FPGA Optimization The start point a
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Sequential Process without a Sensit
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egin if RST = '1' then DO
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Multiple Wait Statements Descriptio
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Functions and Procedures VHDL Langu
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VHDL Language Support Example 6-24
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STANDARD Package VHDL Language Supp
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VHDL Language Support Note Function
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Packages Enumeration Types Integer
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Table 6-4 Objects VHDL Language Sup
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Wait Statement Loop Statement Table
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VHDL Reserved Words The following t
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Verilog Language Support Chapter 7
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Behavioral Verilog Features Verilog
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Verilog Language Support Example 7-
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Table 7-1 Expressions Bitwise Negat
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Modules Verilog Language Support In
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Procedural Assignments Verilog Lang
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Verilog Language Support Casez trea
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While Loops Verilog Language Suppor
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Verilog Language Support Example 7-
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Verilog Language Support The main l
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Verilog Language Support • You ca
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Example 7-9 Function Declaration an
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Blocking Versus Non-Blocking Proced
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Include Files Verilog Language Supp
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Verilog Language Support Each insta
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Parameters Verilog Language Support
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Verilog Language Support • Design
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Verilog Meta Comments Verilog Langu
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Table 7-4 Data Types Registers Vect
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Table 7-8 Design Hierarchy Module d
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Verilog Reserved Keywords Verilog L
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Command Line Mode Introduction Chap
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Command Line Mode • Script File
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Command Line Mode • Second column
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Table 8-4 HDL Options (VHDL and Ver
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Command Line Mode Table 8-6 Target
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Command Line Mode • To get a list
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Elaborate Command Time Command Comm
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♦ smallcntr.vhd Command Line Mode
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Command Line Mode You can improve t
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Command Line Mode Sometimes, XST is
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XST Shell Command Line Mode To use
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Case 2 Command Line Mode Each desig
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Log File Analysis Introduction This
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Quiet Mode Timing Report Log File A
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RAM Style : Auto ROM Extraction : y
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Synthesizing Unit . Related source
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# Counters : 2 # 4-bit up counter :
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Log File Analysis Data Path: sixty_
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CPLD Log File Log File Analysis The
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Analyzing Entity (Architecture ).
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Log File Analysis =================
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XST Naming Conventions This appendi
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