AN 917: Reset Design Techniques for Intel® Hyperflex™ Architecture FPGAs

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ID 683539
Date 1/05/2021
Public
Document Table of Contents
Document Table of Contents x
1. AN 917: Reset Design Techniques for Intel® Hyperflex™ Architecture FPGAs
1. AN 917: Reset Design Techniques for Intel® Hyperflex™ Architecture FPGAs x
1.1. General Reset Recommendations 1.2. Reset Design Strategies 1.3. Analyzing Resets with Design Assistant 1.4. Implementing Reset Circuitry 1.5. Document Revision History for AN 917: Reset Design Techniques for Intel® Hyperflex™ Architecture FPGAs
1.1. General Reset Recommendations x
1.1.1. Limit Reset Usage 1.1.2. Hyper-Registers Require Synchronous Reset
1.2. Reset Design Strategies x
1.2.1. Asynchronous Reset Design Strategies 1.2.2. Synchronous Reset Design Strategies
1.2.1. Asynchronous Reset Design Strategies x
1.2.1.1. Recovery and Removal Checks
1.3. Analyzing Resets with Design Assistant x
1.3.1. Example: Asynchronous Reset Design Assistant Analysis 1.3.2. Example: Synchronous Reset Design Assistant Analysis
1.3.1. Example: Asynchronous Reset Design Assistant Analysis x
1.3.1.1. Adding SDC Constraints to Asynchronous Reset Circuitry
1.4. Implementing Reset Circuitry x
1.4.1. Reset Coding Techniques 1.4.2. Avoiding Common Reset Coding Issues 1.4.3. Generating Synchronous Reset Trees 1.4.4. Reset Removal on Multi Clock Domain Designs 1.4.5. Using the Reset Release Intel® FPGA IP 1.4.6. Adding Clock Cycles to the Reset Sequence
1.4.1. Reset Coding Techniques x
1.4.1.1. Converting to Synchronous Resets
1.4.2. Avoiding Common Reset Coding Issues x
1.4.2.1. Coding Synchronous Reset with Follower Registers 1.4.2.2. Coding Reset-Related Optimizations
1.4.3. Generating Synchronous Reset Trees x
1.4.3.1. Reset Distribution through Hyper-Pipelining and Hyper-Retiming 1.4.3.2. Adding Pipeline Registers and Automatic Register Duplication
1.4.6. Adding Clock Cycles to the Reset Sequence x
1.4.6.1. C-Cycle Equivalence 1.4.6.2. Determining the Reset Sequence Requirement
1. AN 917: Reset Design Techniques for Intel® Hyperflex™ Architecture FPGAs

1.4.3. Generating Synchronous Reset Trees

A synchronous reset can easily fan-out to a large destination, like any broadcast signal. While the use of synchronous reset over asynchronous reset eases timing restrictions, this technique does not remove all performance restrictions. You must use reset in a careful manner. The logic that does not require synchronous reset can help with timing. You need not remove all resets, especially those that are running on slower clock domains. Focus reset strategies on design blocks that must run at high-speed.

To fix a large fan-out on a synchronous reset, you must duplicate and pipeline the reset to provide retiming ability on all the data paths using the reset as part of the logic.

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