Xilinx Constraints Guide

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Chapter 4: Xilinx Constraints Delay Symbol Name Path Type Default io_pad_i IO pad to input propagation delay Enabled io_t_pad IO tristate to pad propagation delay Enabled io_o_i IO output to input propagation delay. Disabled for tristated IOBs. Enabled io_o_pad IO output to pad propagation delay. Enabled PCF Syntax Same as UCF Syntax. Constraints Guide 104 www.xilinx.com UG625 (v. 13.2) July 6, 2011
DRIVE (Drive) The DRIVE (Drive) constraint: Architecture Support Applicable Elements • Is a basic mapping directive Chapter 4: Xilinx Constraints • Selects the output for drive strength for all supported FPGA architectures. • Selects output drive strength (mA) for the SelectIO technology buffers that use the LVTTL, LVCMOS12, LVCMOS15, LVCMOS18, LVCMOS25, or LVCMOS33 interface I/O standard Applies to FPGA devices. Does not apply to CPLD devices. This constraint may be used with an FPGA device in one or more of the following design elements, or categories of design elements. Not all devices support all elements. To see which design elements can be used with which devices, see the Libraries Guides. For more information, see the device data sheet. • IOB output components (such as OBUF and OFD) • SelectIO technology output buffers with: – IOSTANDARD = LVTTL – LVCMOS15 – LVCMOS18 – LVCMOS25, or – LVCMOS33 • Nets Propagation Rules DRIVE is illegal when attached to a net or signal, except when the net or signal is connected to a pad. In this case, DRIVE is treated as attached to the pad instance. When attached to a design element, DRIVE is propagated to all applicable elements in the hierarchy below the 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. Schematic Syntax • Attach to a valid IOB output component • Attribute Name DRIVE • Attribute Values For a list of the constraint values, see the UCF and NCF Syntax section below. Constraints Guide UG625 (v. 13.2) July 6, 2011 www.xilinx.com 105
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Constraints Guide UG625 (v. 13.2) J
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Table of Contents Revision History
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IBUF_DELAY_VALUE (Input Buffer Dela
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Constraint Types Attributes and Con
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Grouping Constraints for Timing Cha
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The name qualifier can include the
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Physical Constraints Mapping Note T
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Placement Constraints Chapter 1: Co
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Routing Directives Routing directiv
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Timing Constraints Chapter 1: Const
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UCF Timing Constraint Support From-
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Timing Model Constraint Priority Ch
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Chapter 2 Entry Strategies for Xili
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Constraint Schematic VHDL Verilog L
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An attribute can be declared in an
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User Constraints File (UCF) UCF Flo
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Syntax Chapter 2: Entry Strategies
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Entering Multiple Constraints File
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Chapter 2: Entry Strategies for Xil
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Running Constraints Editor As a Sta
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Defining I/O Pin Configurations Cha
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Placement LOC Constraint Assignment
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Verilog Example -------------module
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Chapter 2: Entry Strategies for Xil
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Timing Specification Priorities Cha
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Timing Constraint Strategies Chapte
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Page 55 and 56: The global OFFSET IN constraint for
Page 57 and 58: The PERIOD constraint syntax for th
Page 59 and 60: Example Chapter 3: Timing Constrain
Page 61 and 62: Chapter 3: Timing Constraint Strate
Page 63 and 64: The global OFFSET OUT constraints f
Page 65 and 66: Multi-Cycle Paths Chapter 3: Timing
Page 67 and 68: Xilinx Constraints Each Xilinx® co
Page 69 and 70: RANGE Chapter 4: Xilinx Constraints
Page 71 and 72: Chapter 4: Xilinx Constraints Range
Page 73 and 74: COMPRESSION GROUP PLACE Chapter 4:
Page 75 and 76: Defining From Timing Groups Chapter
Page 77 and 78: BEL (BEL) The BEL (BEL) constraint:
Page 79 and 80: BLKNM (Block Name) Architecture Sup
Page 81 and 82: BUFG (BUFG) The BUFG (BUFG) constra
Page 83 and 84: Clock Dedicated Route (CLOCK_DEDICA
Page 85 and 86: COMPGRP (Component Group) Architect
Page 87 and 88: • S_SELECTMAP16 Slave SelectMAP M
Page 89 and 90: Verilog Syntax Chapter 4: Xilinx Co
Page 93 and 94: PCF Syntax CONFIG DCI_CASCADE = ",
Page 95 and 96: Default (DEFAULT) Chapter 4: Xilinx
Page 97 and 98: Example (* KEEPER = “TRUE” *) D
Page 99 and 100: DIFF_TERM (Diff_Term) Architecture
Page 101 and 102: DIRECTED_ROUTING (Directed Routing)
Page 103: DISABLE (Disable) The DISABLE (Disa
Page 107 and 108: XCF Syntax MODEL “entity_name”
Page 109 and 110: ENABLE (Enable) The ENABLE (Enable)
Page 111 and 112: ENABLE_SUSPEND (Enable Suspend) Arc
Page 115 and 116: Constraints Editor Syntax Chapter 4
Page 117 and 118: VHDL Syntax Declare the VHDL constr
Page 119 and 120: UCF and NCF Syntax NET “signal_na
Page 121 and 122: Chapter 4: Xilinx Constraints You a
Page 123 and 124: Constraints Editor Syntax Chapter 4
Page 125 and 126: HBLKNM (Hierarchical Block Name) Ar
Page 127 and 128: HIODELAY_GROUP (HIODELAY Group) Arc
Page 129 and 130: VHDL Syntax Declare the VHDL constr
Page 131 and 132: HU_SET (HU Set) The HU_SET (HU Set)
Page 133 and 134: IBUF_DELAY_VALUE (Input Buffer Dela
Page 135 and 136: IFD_DELAY_VALUE (IFD Delay Value) T
Page 137 and 138: IN_TERM (In Term) Architecture Supp
Page 139 and 140: INREG (Input Registers) Architectur
Page 141 and 142: IOB (IOB) The IOB constraint: • I
Page 143 and 144: IOBDELAY (Input Output Block Delay)
Page 145 and 146: IODELAY_GROUP (IODELAY Group) Limit
Page 147 and 148: IOSTANDARD (Input Output Standard)
Page 149 and 150: Pinout and Area Constraints Editor
Page 153 and 154: Architecture Support Applicable Ele
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Keeper (KEEPER) Architecture Suppor
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LOC (Location) The LOC (Location) c
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Chapter 4: Xilinx Constraints The w
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LOC Range Constraint Examples Const
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PlanAhead Syntax Chapter 4: Xilinx
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Schematic LOC=P17 Chapter 4: Xilinx
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Example One Chapter 4: Xilinx Const
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Slices Prohibited Example Two Chapt
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LOCK_PINS (Lock Pins) Architecture
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where value is any chosen name unde
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MAP (Map) Architecture Support Appl
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Specify the Verilog constraint as f
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Architecture Support Applicable Ele
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MAXDELAY (Maximum Delay) Architectu
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PCF Syntax item MAXDELAY = maxvalue
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MAXSKEW (Maximum Skew) The MAXSKEW
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FPGA Editor Syntax Chapter 4: Xilin
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MIODELAY_GROUP (MIODELAY Group) Arc
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VHDL Syntax Declare the VHDL constr
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UCF and NCF Syntax Chapter 4: Xilin
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where Chapter 4: Xilinx Constraints
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Falling Edge Constraints Chapter 4:
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PlanAhead Syntax Chapter 4: Xilinx
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where Chapter 4: Xilinx Constraints
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UCF Syntax NET “clock” TNM_NET
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Verilog Syntax Chapter 4: Xilinx Co
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Attribute OUT_TERM: string; Specify
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TIMESPEC PERIOD Method Chapter 4: X
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Examples of a Primary Clock with De
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where • period is the required cl
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New PERIOD Specifications Output Pi
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Post CRC (POST_CRC) Architecture Su
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Post CRC Frequency (POST_CRC_FREQ)
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Post CRC Signal (POST_CRC_SIGNAL) A
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PRIORITY (Priority) Architecture Su
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The following are not supported: Ch
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PULLDOWN (Pulldown) Architecture Su
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PULLUP (Pullup) Architecture Suppor
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PWR_MODE (Power Mode) Architecture
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REG (Registers) The REG (Registers)
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RLOC (Relative Location) The Relati
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RLOC = X3Y4 Chapter 4: Xilinx Const
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Linking Sets Set Linkage Chapter 4:
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Chapter 4: Xilinx Constraints by th
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Linking Two HU_SET Sets Chapter 4:
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Specify the VHDL constraint as foll
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Chapter 4: Xilinx Constraints Diffe
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H_SET (H Set) Chapter 4: Xilinx Con
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Chapter 4: Xilinx Constraints The n
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Syntax Examples Chapter 4: Xilinx C
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RLOC_RANGE (Relative Location Range
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where the relative X values (m1 and
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UCF and NCF Syntax NET “mysignal
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VHDL Syntax Chapter 4: Xilinx Const
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SLOW (Slow) The SLOW (Slow) constra
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STEPPING (Stepping) Architecture Su
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VHDL Syntax Chapter 4: Xilinx Const
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Constraints Editor Syntax Chapter 4
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Chapter 4: Xilinx Constraints The f
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TIMEGRP (Timing Group) The TIMEGRP
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Defining Latch Subgroups by Gate Se
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Chapter 4: Xilinx Constraints When
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PCF Syntax TIMEGRP name; TIMEGRP na
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Separators FROM-TO Syntax TIMESPEC
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TNM (Timing Name) Chapter 4: Xilinx
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Chapter 4: Xilinx Constraints A qua
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TNM_NET (Timing Name Net) The TNM_N
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Schematic Syntax • Attach to a ne
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TPSYNC (Timing Point Synchronizatio
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UCF and NCF Syntax NET “net_name
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Using TPTHRU in a FROM TO Constrain
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TSidentifier (Timing Specification
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Ignoring Paths Note This form is no
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Chapter 4: Xilinx Constraints If yo
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Use Low Skew Lines (USELOWSKEWLINES
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VCCAUX (VCCAUX) Architecture Suppor
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VREF (VREF) The VREF (VREF) constra
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XBLKNM (XBLKNM) Architecture Suppor
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Additional Resources Appendix • X
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