AN 919: Improving Quality of Results with Design Assistant

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ID 683369
Date 4/26/2024
Public
Document Table of Contents
Document Table of Contents x
Improving Quality of Results with Design Assistant Document Revision History for AN 919: Improving Quality of Results with Design Assistant Appendix A: Running Design Assistant Appendix B: Design Assistant Rules
Improving Quality of Results with Design Assistant x
About Design Assistant About the Design Assistant Design Example Fixing SDC and CDC Rules in the Design Assistant Design Example Fixing Other Faults in the Design Assistant Design Example
Appendix A: Running Design Assistant x
Running Design Assistant
Appendix B: Design Assistant Rules x
Timing Closure Rules Clock Domain Crossing and Reset Domain Crossing Rules Intrinsic Margin Rules Combinatorial Logic Levels Reducing High Fan-out Nets Hyper-Retimer Restrictions Initial Power-Up Conditions Rules Reset Release Intel FPGA IP
Reducing High Fan-out Nets x
Duplication Rules Tension and Span Rules
Initial Power-Up Conditions Rules x
Removing Initial Power-Up Conditions
Improving Quality of Results with Design Assistant
Document Revision History for AN 919: Improving Quality of Results with Design Assistant
Appendix A: Running Design Assistant
Appendix B: Design Assistant Rules

Removing Initial Power-Up Conditions

Intel recommends you do not use initial power-up conditions in your RTL. Always reset the design into a known state.
  1. Explicitly specify initial conditions in the RTL: 
    reg q = 1’b1; // q has a default value of ‘1’ always@(posedge clk) begin q <= d; end

    Registers without resets may also have initial conditions. By default, Quartus® Prime determines their FF power-up values automatically.

  2. Turn this setting off and force Quartus® Prime to set all uninitialized registers to 0 at power up by using the following global assignment:
    set_global_assignment ALLOW_POWER_UP_DONT_CARE OFF
    Generally, Intel does not recommend this setting because it can hinder register retiming.
  3. Instead of using a global assignment, target areas of the design to drop automatically generated initial conditions with:
    set_instance_assignment IGNORE_REGISTER_POWER_UP_INITIALIZATION ON -to <instance name>
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