Intel® Quartus® Prime Pro Edition User Guide: Design Recommendations

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Date 3/28/2022
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Document Table of Contents
Document Table of Contents x
1. Recommended HDL Coding Styles 2. Recommended Design Practices 3. Managing Metastability with the Intel® Quartus® Prime Software 4. Intel® Quartus® Prime Pro Edition User Guide: Design Recommendations Archive A. Intel® Quartus® Prime Pro Edition User Guides
1. Recommended HDL Coding Styles x
1.1. Using Provided HDL Templates 1.2. Instantiating IP Cores in HDL 1.3. Inferring Multipliers and DSP Functions 1.4. Inferring Memory Functions from HDL Code 1.5. Register and Latch Coding Guidelines 1.6. General Coding Guidelines 1.7. Designing with Low-Level Primitives 1.8. Recommended HDL Coding Styles Revision History
1.1. Using Provided HDL Templates x
1.1.1. Inserting HDL Code from a Provided Template
1.3. Inferring Multipliers and DSP Functions x
1.3.1. Inferring Multipliers 1.3.2. Inferring Multiply-Accumulator and Multiply-Adder Functions
1.4. Inferring Memory Functions from HDL Code x
1.4.1. Inferring RAM functions from HDL Code 1.4.2. Inferring ROM Functions from HDL Code 1.4.3. Inferring Shift Registers in HDL Code 1.4.4. Inferring FIFOs in HDL Code
1.4.1. Inferring RAM functions from HDL Code x
1.4.1.1. Use Synchronous Memory Blocks 1.4.1.2. Avoid Unsupported Reset and Control Conditions 1.4.1.3. Check Read-During-Write Behavior 1.4.1.4. Controlling RAM Inference and Implementation 1.4.1.5. Single-Clock Synchronous RAM with Old Data Read-During-Write Behavior 1.4.1.6. Single-Clock Synchronous RAM with New Data Read-During-Write Behavior 1.4.1.7. Simple Dual-Port, Dual-Clock Synchronous RAM 1.4.1.8. True Dual-Port Synchronous RAM 1.4.1.9. Mixed-Width Dual-Port RAM 1.4.1.10. RAM with Byte-Enable Signals 1.4.1.11. Specifying Initial Memory Contents at Power-Up
1.4.3. Inferring Shift Registers in HDL Code x
1.4.3.1. Simple Shift Register 1.4.3.2. Shift Register with Evenly Spaced Taps
1.4.4. Inferring FIFOs in HDL Code x
1.4.4.1. Dual Clock FIFO Example in Verilog HDL 1.4.4.2. Dual Clock FIFO Timing Constraints
1.5. Register and Latch Coding Guidelines x
1.5.1. Register Power-Up Values 1.5.2. Secondary Register Control Signals Such as Clear and Clock Enable 1.5.3. Latches
1.5.1. Register Power-Up Values x
1.5.1.1. Specifying a Power-Up Value
1.5.3. Latches x
1.5.3.1. Avoid Unintentional Latch Generation 1.5.3.2. Inferring Latches Correctly
1.6. General Coding Guidelines x
1.6.1. Tri-State Signals 1.6.2. Clock Multiplexing 1.6.3. Adder Trees 1.6.4. State Machine HDL Guidelines 1.6.5. Multiplexer HDL Guidelines 1.6.6. Cyclic Redundancy Check Functions 1.6.7. Comparator HDL Guidelines 1.6.8. Counter HDL Guidelines
1.6.3. Adder Trees x
1.6.3.1. Architectures with 6-Input LUTs in Adaptive Logic Modules
1.6.4. State Machine HDL Guidelines x
1.6.4.1. State Machine Power-Up 1.6.4.2. Verilog HDL State Machines 1.6.4.3. VHDL State Machines
1.6.4.2. Verilog HDL State Machines x
1.6.4.2.1. Verilog-2001 State Machine Coding Example 1.6.4.2.2. SystemVerilog State Machine Coding Example
1.6.4.3. VHDL State Machines x
1.6.4.3.1. VHDL State Machine Coding Example
1.6.5. Multiplexer HDL Guidelines x
1.6.5.1. Intel® Quartus® Prime Software Option for Multiplexer Restructuring 1.6.5.2. Multiplexer Types 1.6.5.3. Implicit Defaults in IF Statements 1.6.5.4. default or OTHERS CASE Assignment
1.6.5.2. Multiplexer Types x
1.6.5.2.1. Binary Multiplexers 1.6.5.2.2. Selector Multiplexers 1.6.5.2.3. Priority Multiplexers
1.6.6. Cyclic Redundancy Check Functions x
1.6.6.1. If Performance is Important, Optimize for Speed 1.6.6.2. Use Separate CRC Blocks Instead of Cascaded Stages 1.6.6.3. Use Separate CRC Blocks Instead of Allowing Blocks to Merge 1.6.6.4. Take Advantage of Latency if Available 1.6.6.5. Save Power by Disabling CRC Blocks When Not in Use 1.6.6.6. Initialize the Device with the Synchronous Load (sload) Signal
2. Recommended Design Practices x
2.1. Following Synchronous FPGA Design Practices 2.2. HDL Design Guidelines 2.3. Use Clock and Register-Control Architectural Features 2.4. Implementing Embedded RAM 2.5. Design Assistant Design Rule Checking 2.6. Recommended Design Practices Revision History
2.1. Following Synchronous FPGA Design Practices x
2.1.1. Implementing Synchronous Designs 2.1.2. Asynchronous Design Hazards
2.2. HDL Design Guidelines x
2.2.1. Considerations for the Intel® Hyperflex™ FPGA Architecture 2.2.2. Optimizing Combinational Logic 2.2.3. Optimizing Clocking Schemes 2.2.4. Optimizing Physical Implementation and Timing Closure 2.2.5. Optimizing Power Consumption 2.2.6. Managing Design Metastability
2.2.2. Optimizing Combinational Logic x
2.2.2.1. Avoid Combinational Loops 2.2.2.2. Avoid Unintended Latch Inference 2.2.2.3. Avoid Delay Chains in Clock Paths 2.2.2.4. Use Synchronous Pulse Generators
2.2.3. Optimizing Clocking Schemes x
2.2.3.1. Register Combinational Logic Outputs 2.2.3.2. Avoid Asynchronous Clock Division 2.2.3.3. Avoid Ripple Counters 2.2.3.4. Use Multiplexed Clocks 2.2.3.5. Use Gated Clocks 2.2.3.6. Use Synchronous Clock Enables
2.2.3.5. Use Gated Clocks x
2.2.3.5.1. Recommended Clock-Gating Methods
2.2.4. Optimizing Physical Implementation and Timing Closure x
2.2.4.1. Planning Physical Implementation 2.2.4.2. Planning FPGA Resources 2.2.4.3. Optimizing for Timing Closure 2.2.4.4. Optimizing Critical Timing Paths
2.3. Use Clock and Register-Control Architectural Features x
2.3.1. Use Global Reset Resources 2.3.2. Use Global Clock Network Resources 2.3.3. Use Clock Region Assignments to Optimize Clock Constraints 2.3.4. Avoid Asynchronous Register Control Signals
2.3.1. Use Global Reset Resources x
2.3.1.1. Use Synchronous Resets 2.3.1.2. Using Asynchronous Resets 2.3.1.3. Use Synchronized Asynchronous Reset
2.3.3. Use Clock Region Assignments to Optimize Clock Constraints x
2.3.3.1. Clock Region Assignments in Intel® Stratix® 10 Devices 2.3.3.2. Clock Region Assignments in Intel® Arria® 10 and Older Device Families
2.5. Design Assistant Design Rule Checking x
2.5.1. Setting Up Design Assistant 2.5.2. Running Design Assistant During Compilation 2.5.3. Running Design Assistant in Analysis Mode 2.5.4. Cross-Probing from Design Assistant 2.5.5. Managing Design Assistant Rules 2.5.6. Design Assistant Rule Categories
2.5.1. Setting Up Design Assistant x
2.5.1.1. Design Assistant Rule Severity Levels
2.5.2. Running Design Assistant During Compilation x
2.5.2.1. Opening Design Assistant Rule Help
2.5.3. Running Design Assistant in Analysis Mode x
2.5.3.1. Launching Design Assistant from Chip Planner 2.5.3.2. Launching Design Assistant from Timing Analyzer
2.5.4. Cross-Probing from Design Assistant x
2.5.4.1. Cross-Probing from Design Assistant to Timing Analyzer 2.5.4.2. Cross-Probing from Design Assistant to Visualization Tools
2.5.5. Managing Design Assistant Rules x
2.5.5.1. Changing the Default Number of Violations per Rule 2.5.5.2. Enabling Rules for Specific Compiler Stages 2.5.5.3. Specifying Rule Parameters for a Specific Compiler Stage 2.5.5.4. Modifying Rule Severity Levels 2.5.5.5. Waiving Design Assistant Rules 2.5.5.6. Design Assistant Tags
2.5.5.5. Waiving Design Assistant Rules x
2.5.5.5.1. Creating Design Assistant Waivers 2.5.5.5.2. Deleting Design Assistant Waivers 2.5.5.5.3. Design Assistant Waiver Tcl Commands
2.5.5.5.1. Creating Design Assistant Waivers x
2.5.5.5.1.1. Design Assistant Waiver Dialog Box
2.5.5.5.3. Design Assistant Waiver Tcl Commands x
2.5.5.5.3.1. drc::add_waiver Command 2.5.5.5.3.2. drc::get_waivers Command 2.5.5.5.3.3. drc::report_waivers Command
3. Managing Metastability with the Intel® Quartus® Prime Software x
3.1. Metastability Analysis in the Intel® Quartus® Prime Software 3.2. Metastability and MTBF Reporting 3.3. MTBF Optimization 3.4. Reducing Metastability Effects 3.5. Scripting Support 3.6. Managing Metastability 3.7. Managing Metastability with the Intel® Quartus® Prime Software Revision History
3.1. Metastability Analysis in the Intel® Quartus® Prime Software x
3.1.1. Data Synchronization Register Chains 3.1.2. Identify Synchronizers for Metastability Analysis 3.1.3. How Timing Constraints Affect Synchronizer Identification and Metastability Analysis
3.2. Metastability and MTBF Reporting x
3.2.1. Metastability Reports 3.2.2. Synchronizer Data Toggle Rate in MTBF Calculation
3.2.1. Metastability Reports x
3.2.1.1. MTBF Summary Report 3.2.1.2. Synchronizer Summary Report 3.2.1.3. Synchronizer Chain Statistics Report in the Timing Analyzer
3.2.1.1. MTBF Summary Report x
3.2.1.1.1. Typical and Worst-Case MTBF of Design 3.2.1.1.2. Synchronizer Chains 3.2.1.1.3. Increasing Available Settling Time
3.3. MTBF Optimization x
3.3.1. Synchronization Register Chain Length
3.4. Reducing Metastability Effects x
3.4.1. Apply Complete System-Centric Timing Constraints for the Timing Analyzer 3.4.2. Force the Identification of Synchronization Registers 3.4.3. Set the Synchronizer Data Toggle Rate 3.4.4. Optimize Metastability During Fitting 3.4.5. Increase the Length of Synchronizers to Protect and Optimize 3.4.6. Increase the Number of Stages Used in Synchronizers 3.4.7. Select a Faster Speed Grade Device
3.5. Scripting Support x
3.5.1. Identifying Synchronizers for Metastability Analysis 3.5.2. Synchronizer Data Toggle Rate in MTBF Calculation 3.5.3. report_metastability and Tcl Command 3.5.4. MTBF Optimization 3.5.5. Synchronization Register Chain Length
1. Recommended HDL Coding Styles
2. Recommended Design Practices
3. Managing Metastability with the Intel® Quartus® Prime Software
4. Intel® Quartus® Prime Pro Edition User Guide: Design Recommendations Archive
A. Intel® Quartus® Prime Pro Edition User Guides

3.3.1. Synchronization Register Chain Length

The Synchronization Register Chain Length option specifies how many registers should be protected from optimizations that might reduce MTBF for each register chain, and controls how many registers should be optimized to increase MTBF with the Optimize Design for Metastability option.

For example, if the Synchronization Register Chain Length option is set to 2, optimizations such as register duplication or logic retiming are prevented from being performed on the first two registers in all identified synchronization chains. The first two registers are also optimized to improve MTBF when the Optimize Design for Metastability option is turned on.

The default setting for the Synchronization Register Chain Length option is 3. The first register of a synchronization chain is always protected from operations that might reduce MTBF, but you should set the protection length to protect more of the synchronizer chain. Intel recommends that you set this option to the maximum length of synchronization chains you have in your design so that all synchronization registers are preserved and optimized for MTBF.

Click Assignments > Settings > Compiler Settings > Advanced Settings (Synthesis) to change the global Synchronization Register Chain Length option.

You can also set the Synchronization Register Chain Length on a node or an entity in the Assignment Editor. You can set this value on the first register in a synchronization chain to specify how many registers to protect and optimize in this chain. This individual setting is useful if you want to protect and optimize extra registers that you have created in a specific synchronization chain that has low MTBF, or optimize less registers for MTBF in a specific chain where the maximum frequency or timing performance is not being met. To make the global setting with Tcl, use the following command: 

set_global_assignment -name SYNCHRONIZATION_REGISTER_CHAIN_LENGTH <number of registers>

To apply the assignment to a design instance or the first register in a specific chain with Tcl, use the following command:

set_instance_assignment -name SYNCHRONIZATION_REGISTER_CHAIN_LENGTH <number of registers> -to <register or instance name>
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