External Memory Interface Handbook Volume 3: Reference Material

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ID 683841
Date 7/24/2019
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Document Table of Contents

3.9.5.2. Technical Restrictions

Certain criteria must be met in order to use periodic OCT recalibration.

The periodic OCT recalibration engine is enabled only when all of the following criteria are met:

  • The memory interface is configured to use the Altera Hard Memory Controller for DDR4.
  • The memory interface is configured for either DDR4 UDIMM or component topologies. RDIMM and LRDIMM topologies are not supported.
  • The memory interface is not used with the hardened processor subsystem.
  • The memory interface does not use Ping-Pong PHY.
  • The memory interface does not use calibrated I/O standards for address, command, or clock signals.
  • The memory interface uses calibrated I/O standards for the data bus.
  • The memory does not use the memory mapped register (MMR) interface of the HMC, including ECC modes.
  • You have not explicitly disabled periodic OCT recalibration in the parameter editor.
  • The specified device is a production level device (that is, not an ES/ES2/ES3 class device).

Periodic OCT recalibration requires that each EMIF instance in the design employ a dedicated RZQ resistor. Because this restriction cannot be detected at IP generation time, you must explicitly disable the periodic OCT recalibration engine for a given interface if it shares an RZQ resistor with another interface. Ensure that you observe this restriction when automatically upgrading EMIF IP from older versions of the Quartus Prime software.

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