External Memory Interfaces Arria® 10 FPGA IP User Guide

ID 683106
Date 11/28/2024
Public
Document Table of Contents

7.3.3.2. x4 DIMM Implementation

DIMMS using a x4 DQS configuration require remapping of the DQS signals to achieve compatibility between the EMIF IP and the JEDEC standard DIMM socket connections.

The necessary remapping is shown in the table below. You can implement this DQS remapping in either RTL logic or in your schematic wiring connections.

Table 263.  Mapping of DQS Signals Between DIMM and the EMIF IP
DIMM   Quartus® Prime EMIF IP
DQS0 DQ[3:0]   DQS0 DQ[3:0]
DQS9 DQ[7:4]   DQS1 DQ[7:4]
DQS1 DQ[11:8]   DQS2 DQ[11:8]
DQS10 DQ[15:12]   DQS3 DQ[15:12]
DQS2 DQ[19:16]   DQS4 DQ[19:16]
DQS11 DQ[23:20]   DQS5 DQ[23:20]
DQS3 DQ[27:24]   DQS6 DQ[27:24]
DQS12 DQ[31:28]   DQS7 DQ[31:28]
DQS4 DQ[35:32]   DQS8 DQ[35:32]
DQS13 DQ[39:36]   DQS9 DQ[39:36]
DQS5 DQ[43:40]   DQS10 DQ[43:40]
DQS14 DQ[47:44]   DQS11 DQ[47:44]
DQS6 DQ[51:48]   DQS12 DQ[51:48]
DQS15 DQ[55:52]   DQS13 DQ[55:52]
DQS7 DQ[59:56]   DQS14 DQ[59:56]
DQS16 DQ[63:60]   DQS15 DQ[63:60]
DQS8 DQ[67:64]   DQS16 DQ[67:64]
DQS17 DQ[71:68]   DQS17 DQ[71:68]

Data Bus Connection Mapping Flow

  1. Connect all FPGA DQ pins accordingly to DIMM DQ pins. No remapping is required.
  2. DQS/DQSn remapping is required either on the board schematics or in the RTL code.
  3. An example mapping is shown below, with reference to the above table values:
    FPGA (DQS0) to DIMM (DQS0)
    FPGA (DQS1) to DIMM (DQS9)
    FPGA (DQS2) to DIMM (DQS1)
    ...
    FPGA (DQS16) to DIMM (DQS8)
    FPGA (DQS17) to DIMM (DQS17)

When designing a board to support x4 DQS groups, Intel® recommends that you make it compatible for x8 mode, for the following reasons:

  • Provides the flexibility of x4 and x8 DIMM support.
  • Allows use of x8 DQS group connectivity rules.
  • Allows use of x8 timing rules for matching. Intel® strongly recommends adhering to x4/x8 interoperability rules when designing a DIMM interface, even if the primary use case is to support x4 DIMMs only, be