External Memory Interface Handbook Volume 2: Design Guidelines

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ID 683385
Date 5/08/2017
Public
Document Table of Contents

10.1.2. Dedicated DLL Resources

Intel® devices typically use DLLs to enhance data capture at the FPGA. While multiple external memory interfaces can usually share DLL resources, fitter issues can occur when there is insufficient planning before HDL coding.

If DLL sharing is required, Intel® gives the following recommendations for each instance of the IP that shares the DLL resources:

  • Must have compatible DLL requirements—same frequency and mode.
  • Exports its autogenerated DLL instance out of its own dedicated PHY hierarchy and into the top-level design file. This procedure allows easy comparison of the generated DLL’s mode, and allows you to explicitly show the required DLL sharing between two IP blocks in the HDL
Note: The Quartus Prime fitter does not dynamically merge DLL instances.

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