Device Family: Intel® Arria® 10 GT, Intel® Arria® 10 GX, Intel® Arria® 10 SX

Type: Answers

Area: EMIF, Intellectual Property


IP Product: DDR4 Hilo Daughter Card

Why do I see an extra read data valid assertion on the Arria 10 EMIF MMR interface?

Description

If your Arria® 10 memory controller IP has the MMR interface enabled, you may notice that the mmr_readdatavalid signal asserts occasionally even when no read commands are issued.

 

The mmr_readdatavalid assertion originates from the memory controller\'s internal read command and could cause the Avalon Master to capture the wrong read data.

Workaround/Fix

The Avalon Master must only accept mmr_readdatavalid based on the following requirement:

  • mmr_readdatavalid returns 1 cycle after issuing read request to MMR register ecc1, ecc2, ecc3, ecc4.
  • mmr_readdatavalid returns 3 cycles after issuing read request to all other MMR registers other than ecc1, ecc2, ecc3, ecc4.

Example: The Avalon Master should only accept mmr_readdatavalid one clock cycle after sending read request to register ecc1 (with mmr_waitrequest signal low).