External Memory Interfaces Agilex™ 7 M-Series FPGA IP User Guide

Download PDF
ID 772538
Date 4/01/2024
Public
Document Table of Contents
Document Table of Contents x
1. About the External Memory Interfaces Agilex™ 7 M-Series FPGA IP 2. Agilex™ 7 M-Series FPGA EMIF IP – Introduction 3. Agilex™ 7 M-Series FPGA EMIF IP – Product Architecture 4. Agilex™ 7 M-Series FPGA EMIF IP – End-User Signals 5. Agilex™ 7 M-Series FPGA EMIF IP – Simulating Memory IP 6. Agilex™ 7 M-Series FPGA EMIF IP – DDR4 Support 7. Agilex™ 7 M-Series FPGA EMIF IP – DDR5 Support 8. Agilex™ 7 M-Series FPGA EMIF IP – LPDDR5 Support 9. Agilex™ 7 M-Series FPGA EMIF IP – Timing Closure 10. Agilex™ 7 M-Series FPGA EMIF IP – Controller Optimization 11. Agilex™ 7 M-Series FPGA EMIF IP – Debugging 12. Document Revision History for External Memory Interfaces Agilex™ 7 M-Series FPGA IP User Guide
1. About the External Memory Interfaces Agilex™ 7 M-Series FPGA IP x
1.1. Release Information
2. Agilex™ 7 M-Series FPGA EMIF IP – Introduction x
2.1. Agilex™ 7 M-Series EMIF IP Protocol and Feature Support 2.2. Agilex™ 7 M-Series EMIF IP Design Flow 2.3. Agilex™ 7 M-Series EMIF IP Design Checklist
3. Agilex™ 7 M-Series FPGA EMIF IP – Product Architecture x
3.1. Agilex™ 7 M-Series EMIF Architecture: Introduction 3.2. Agilex™ 7 M-Series EMIF Sequencer 3.3. Agilex™ 7 M-Series EMIF Controller 3.4. Agilex™ 7 M-Series EMIF IP for Hard Processor Subsystem (HPS)
3.1. Agilex™ 7 M-Series EMIF Architecture: Introduction x
3.1.1. Agilex™ 7 M-Series EMIF Architecture: I/O Subsystem 3.1.2. Agilex™ 7 M-Series EMIF Architecture: I/O SSM 3.1.3. Agilex™ 7 M-Series EMIF Architecture: I/O Bank 3.1.4. Agilex™ 7 M-Series EMIF Architecture: I/O Lane 3.1.5. Agilex™ 7 M-Series EMIF Architecture: Input DQS Clock Tree 3.1.6. Agilex™ 7 M-Series EMIF Architecture: PHY Clock Tree 3.1.7. Agilex™ 7 M-Series EMIF Architecture: PLL Reference Clock Networks 3.1.8. Agilex™ 7 M-Series EMIF Architecture: Clock Phase Alignment 3.1.9. User Clock in Different Core Access Modes
3.1.3. Agilex™ 7 M-Series EMIF Architecture: I/O Bank x
3.1.3.1. Lockstep Configuration Two Controllers in Lockstep Within One IO96 Bank Two/Three Controllers in Lockstep Within One IO96 Bank 3.1.3.2. DDR4 Pin Placement 3.1.3.3. DDR5 Pin Placement 3.1.3.4. LPDDR5 Pin Placement 3.1.3.5. I/O Sub-Bank Usage
3.2. Agilex™ 7 M-Series EMIF Sequencer x
3.2.1. Agilex™ 7 M-Series Mailbox Structure and Register Definitions
3.2.1. Agilex™ 7 M-Series Mailbox Structure and Register Definitions x
3.2.1.1. Mailbox Supported Commands 3.2.1.2. Mailbox Command Definitions
3.3. Agilex™ 7 M-Series EMIF Controller x
3.3.1. Hard Memory Controller
3.3.1. Hard Memory Controller x
3.3.1.1. Hard Memory Controller Features
4. Agilex™ 7 M-Series FPGA EMIF IP – End-User Signals x
4.1. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for DDR4 4.2. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for DDR5 4.3. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for LPDDR5 4.4. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for EMIF Calibration Component
4.1. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for DDR4 x
4.1.1. ref_clk for EMIF 4.1.2. core_init_n for EMIF 4.1.3. usr_async_clk for EMIF 4.1.4. usr_clk for EMIF 4.1.5. usr_rst_n for EMIF 4.1.6. s0_axi4 for EMIF 4.1.7. mem for EMIF 4.1.8. oct for EMIF
4.2. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for DDR5 x
4.2.1. ref_clk for EMIF 4.2.2. core_init_n for EMIF 4.2.3. usr_async_clk for EMIF 4.2.4. usr_clk for EMIF 4.2.5. usr_rst_n for EMIF 4.2.6. s0_axi4 for EMIF 4.2.7. mem for EMIF 4.2.8. i3c for EMIF 4.2.9. mem_lbd for EMIF 4.2.10. mem_lbs for EMIF 4.2.11. oct for EMIF
4.3. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for LPDDR5 x
4.3.1. ref_clk for EMIF 4.3.2. core_init_n for EMIF 4.3.3. usr_async_clk for EMIF 4.3.4. usr_clk for EMIF 4.3.5. usr_rst_n for EMIF 4.3.6. s0_axi4 for EMIF 4.3.7. mem for EMIF 4.3.8. oct for EMIF
4.4. Agilex™ 7 M-Series FPGA EMIF IP Interfaces for EMIF Calibration Component x
4.4.1. s0_axi4lite_clk for EMIF 4.4.2. s0_axi4lite_rst_n for EMIF 4.4.3. s0_axi4lite for EMIF
5. Agilex™ 7 M-Series FPGA EMIF IP – Simulating Memory IP x
5.1. Simulation Walkthrough
5.1. Simulation Walkthrough x
5.1.1. Calibration 5.1.2. Simulation Scripts 5.1.3. Functional Simulation with Verilog HDL 5.1.4. Simulating the Design Example
6. Agilex™ 7 M-Series FPGA EMIF IP – DDR4 Support x
6.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for DDR4 6.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning 6.3. DDR4 Board Design Guidelines
6.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for DDR4 x
6.1.1. Agilex™ 7 FPGA EMIF IP Parameter for DDR4 6.1.2. Agilex™ 7 FPGA EMIF Memory Device Description IP (DDR4) Parameter Descriptions 6.1.3. Agilex™ 7 FPGA EMIF Calibration IP Parameter Descriptions
6.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning x
6.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins 6.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources 6.2.3. Pin Guidelines for Agilex™ 7 M-Series FPGA EMIF IP 6.2.4. Pin Placements for Agilex™ 7 M-Series FPGA DDR4 EMIF IP
6.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins x
6.2.1.1. Estimating Pin Requirements 6.2.1.2. DIMM Options 6.2.1.3. Maximum Number of Interfaces
6.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources x
6.2.2.1. OCT 6.2.2.2. PLL
6.2.4. Pin Placements for Agilex™ 7 M-Series FPGA DDR4 EMIF IP x
6.2.4.1. Address and Command Pin Placement for DDR4 6.2.4.2. DDR4 Data Width Mapping 6.2.4.3. General Guidelines - DDR4 6.2.4.4. x4 DIMM Implementation 6.2.4.5. Specific Pin Connection Requirements 6.2.4.6. Command and Address Signals 6.2.4.7. Clock Signals 6.2.4.8. Data, Data Strobes, DM/DBI, and Optional ECC Signals
6.3. DDR4 Board Design Guidelines x
6.3.1. Terminations for DDR4 with Agilex™ 7 M-Series Devices 6.3.2. General Layout Routing Guidelines 6.3.3. Reference Stackup 6.3.4. Agilex™ 7 M-Series EMIF-Specific Routing Guidelines for Various DDR4 Topologies 6.3.5. DDR4 Routing Guidelines: Discrete (Component) Topologies
6.3.1. Terminations for DDR4 with Agilex™ 7 M-Series Devices x
6.3.1.1. Dynamic On-Chip Termination (OCT) 6.3.1.2. Dynamic On-Die Termination (ODT) in DDR4 6.3.1.3. Choosing Terminations on Agilex™ 7 M-Series FPGA Devices 6.3.1.4. On-Chip Termination Recommendations for Agilex™ 7 M-Series FPGA Devices
6.3.4. Agilex™ 7 M-Series EMIF-Specific Routing Guidelines for Various DDR4 Topologies x
6.3.4.1. One DIMM per Channel (1DPC) for UDIMM, RDIMM, and SODIMM DDR4 Topologies 6.3.4.2. Skew Matching Guidelines for DIMM Configurations 6.3.4.3. Power Delivery Recommendations for the Memory / DIMM Side
6.3.5. DDR4 Routing Guidelines: Discrete (Component) Topologies x
6.3.5.1. Single Rank x 8 Discrete (Component) Topology 6.3.5.2. Single Rank x 16 Discrete (Component) Topology 6.3.5.3. ADDR/CMD Reference Voltage/RESET Signal Routing Guidelines for Single Rank x 8 and Single Rank x 16 Discrete (Component) Topologies 6.3.5.4. Skew Matching Guidelines for DDR4 Discrete Configurations 6.3.5.5. Power Delivery Recommendations for DDR4 Discrete Configurations 6.3.5.6. Agilex™ 7 M-Series EMIF Pin Swapping Guidelines
6.3.5.6. Agilex™ 7 M-Series EMIF Pin Swapping Guidelines x
6.3.5.6.1. DDR4 Byte Lane Swapping 6.3.5.6.2. DDR4 Address and Command and CLK Lane 6.3.5.6.3. DDR4 Interface x8 Data Lane 6.3.5.6.4. DDR4 Interface x4 Data Lane 6.3.5.6.5. Pin Swizzling
7. Agilex™ 7 M-Series FPGA EMIF IP – DDR5 Support x
7.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for DDR5 7.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning 7.3. DDR5 Board Design Guidelines
7.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for DDR5 x
7.1.1. Agilex™ 7 FPGA EMIF IP Parameter for DDR5 7.1.2. Agilex™ 7 FPGA EMIF Memory Device Description IP (DDR5) Parameter Descriptions 7.1.3. Agilex™ 7 FPGA EMIF Calibration IP Parameter Descriptions
7.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning x
7.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins 7.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources 7.2.3. Pin Guidelines for Agilex™ 7 M-Series FPGA EMIF IP 7.2.4. Pin Placements for Agilex™ 7 M-Series FPGA DDR5 EMIF IP 7.2.5. Agilex™ 7 M-Series EMIF Pin Swapping Guidelines
7.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins x
7.2.1.1. Estimating Pin Requirements 7.2.1.2. DIMM Options 7.2.1.3. Maximum Number of Interfaces
7.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources x
7.2.2.1. OCT 7.2.2.2. PLL
7.2.3. Pin Guidelines for Agilex™ 7 M-Series FPGA EMIF IP x
7.2.3.1. General Guidelines - DDR5 7.2.3.2. x4 DIMM Implementation 7.2.3.3. Specific Pin Connection Requirements 7.2.3.4. Command and Address Signals 7.2.3.5. Clock Signals 7.2.3.6. Data, Data Strobes, DM, and Optional ECC Signals
7.2.4. Pin Placements for Agilex™ 7 M-Series FPGA DDR5 EMIF IP x
7.2.4.1. Address and Command Pin Placement for DDR5 7.2.4.2. DDR5 Data Width Mapping
7.2.5. Agilex™ 7 M-Series EMIF Pin Swapping Guidelines x
7.2.5.1. DDR5 Byte Lane Swapping 7.2.5.2. DDR5 Address and Command and CLK Lane 7.2.5.3. DDR5 Interface x8 Data Lane 7.2.5.4. DDR5 Interface x4 Data Lane 7.2.5.5. Pin Swizzling
7.3. DDR5 Board Design Guidelines x
7.3.1. PCB Stack-up and Design Considerations 7.3.2. General Design Considerations 7.3.3. DDR Differential Signals Routing 7.3.4. Ground Plane and Return Path 7.3.5. RDIMM, UDIMM, and SODIMM Break-in Layout Guidelines 7.3.6. DRAM Break-in Layout Guidelines 7.3.7. DDR5 PCB Layout Guidelines 7.3.8. DDR5 Simulation Strategy
7.3.7. DDR5 PCB Layout Guidelines x
7.3.7.1. DDR5 Discrete Component/Memory Down Topology: up to 40-Bit Interface (1 Rank x8 or x16, 2 Rank x8 or x16) 7.3.7.2. Routing Guidelines for DDR5 Memory Down: 1 Rank or 2 Rank (x8 bit or x16 bit) Configurations 7.3.7.3. Routing Guidelines for DDR5 RDIMM, UDIMM, and SODIMM Configurations 7.3.7.4. Example of a DDR5 layout on Intel FPGA Platform Board
8. Agilex™ 7 M-Series FPGA EMIF IP – LPDDR5 Support x
8.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for LPDDR5 8.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning 8.3. LPDDR5 Board Design Guidelines
8.1. Agilex™ 7 M-Series FPGA EMIF IP Parameters for LPDDR5 x
8.1.1. Agilex™ 7 FPGA EMIF IP Parameter for LPDDR5 8.1.2. Agilex™ 7 FPGA EMIF Memory Device Description IP (LPDDR5) Parameter Descriptions 8.1.3. Agilex™ 7 FPGA EMIF Calibration IP Parameter Descriptions
8.2. Agilex™ 7 M-Series FPGA EMIF IP Pin and Resource Planning x
8.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins 8.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources 8.2.3. Pin Guidelines for Agilex™ 7 M-Series FPGA EMIF IP 8.2.4. Pin Placements for Agilex™ 7 M-Series FPGA LPDDR5 EMIF IP
8.2.1. Agilex™ 7 M-Series FPGA EMIF IP Interface Pins x
8.2.1.1. Estimating Pin Requirements 8.2.1.2. DIMM Options 8.2.1.3. Maximum Number of Interfaces
8.2.2. Agilex™ 7 M-Series FPGA EMIF IP Resources x
8.2.2.1. OCT 8.2.2.2. PLL
8.2.3. Pin Guidelines for Agilex™ 7 M-Series FPGA EMIF IP x
8.2.3.1. General Guidelines - LPDDR5 8.2.3.2. Specific Pin Connection Requirements 8.2.3.3. Command and Address Signals 8.2.3.4. Clock Signals
8.2.4. Pin Placements for Agilex™ 7 M-Series FPGA LPDDR5 EMIF IP x
8.2.4.1. Address and Command Pin Placement for LPDDR5 8.2.4.2. LPDDR5 Data Width Mapping 8.2.4.3. LPDDR5 Byte Lane Swapping
8.3. LPDDR5 Board Design Guidelines x
8.3.1. PCB Stack-up and Design Considerations 8.3.2. General Design Considerations 8.3.3. DDR Differential Signals Routing 8.3.4. Ground Plane and Return Path 8.3.5. DRAM Break-in Layout Guidelines 8.3.6. LPDDR5 PCB Layout Guidelines 8.3.7. LPDDR5 Simulation Strategy
8.3.6. LPDDR5 PCB Layout Guidelines x
8.3.6.1. LPDDR5 Discrete Component/Memory Down Topology (1 Rank or 2 Rank, up to 64 Bit Interface) 8.3.6.2. Supported LPDDR5 Topologies 8.3.6.3. Example of an LPDDR5 Layout on an Intel® FPGA Platform Board
9. Agilex™ 7 M-Series FPGA EMIF IP – Timing Closure x
9.1. Timing Closure 9.2. Optimizing Timing
9.1. Timing Closure x
9.1.1. Timing Analysis
9.1.1. Timing Analysis x
9.1.1.1. PHY or Core
10. Agilex™ 7 M-Series FPGA EMIF IP – Controller Optimization x
10.1. Interface Standard 10.2. Bank Management Efficiency 10.3. Data Transfer 10.4. Improving Controller Efficiency
10.4. Improving Controller Efficiency x
10.4.1. Frequency of Operation 10.4.2. Series of Reads or Writes
11. Agilex™ 7 M-Series FPGA EMIF IP – Debugging x
11.1. Interface Configuration Performance Issues 11.2. Functional Issue Evaluation 11.3. Timing Issue Characteristics 11.4. Verifying Memory IP Using the Signal Tap Logic Analyzer 11.5. Debugging with the External Memory Interface Debug Toolkit 11.6. Generating Traffic with the Test Engine IP 11.7. Guidelines for Developing HDL for Traffic Generator
11.1. Interface Configuration Performance Issues x
11.1.1. Interface Configuration Bottleneck and Efficiency Issues
11.2. Functional Issue Evaluation x
11.2.1. Intel® IP Memory Model 11.2.2. Vendor Memory Model 11.2.3. Transcript Window Messages
11.3. Timing Issue Characteristics x
11.3.1. Evaluating FPGA Timing Issues 11.3.2. Evaluating External Memory Interface Timing Issues
11.5. Debugging with the External Memory Interface Debug Toolkit x
11.5.1. Prerequisites for Using the EMIF Debug Toolkit 11.5.2. Configuring Your Design to Use the EMIF Debug Toolkit 11.5.3. Launching the EMIF Debug Toolkit 11.5.4. Using the EMIF Debug Toolkit
11.5.4. Using the EMIF Debug Toolkit x
11.5.4.1. Rerunning Calibration 11.5.4.2. Rerunning the Test Engine 11.5.4.3. Saving Debug Print 11.5.4.4. Calibration Reports 11.5.4.5. Driver Margining Tab 11.5.4.6. Pin Delay Settings Tab
1. About the External Memory Interfaces Agilex™ 7 M-Series FPGA IP
2. Agilex™ 7 M-Series FPGA EMIF IP – Introduction
3. Agilex™ 7 M-Series FPGA EMIF IP – Product Architecture
4. Agilex™ 7 M-Series FPGA EMIF IP – End-User Signals
5. Agilex™ 7 M-Series FPGA EMIF IP – Simulating Memory IP
6. Agilex™ 7 M-Series FPGA EMIF IP – DDR4 Support
7. Agilex™ 7 M-Series FPGA EMIF IP – DDR5 Support
8. Agilex™ 7 M-Series FPGA EMIF IP – LPDDR5 Support
9. Agilex™ 7 M-Series FPGA EMIF IP – Timing Closure
10. Agilex™ 7 M-Series FPGA EMIF IP – Controller Optimization
11. Agilex™ 7 M-Series FPGA EMIF IP – Debugging
12. Document Revision History for External Memory Interfaces Agilex™ 7 M-Series FPGA IP User Guide

3.1.3.1. Lockstep Configuration

To support user data widths greater than 32 bits in DDR4, the external memory interface (EMIF) IP instantiates multiple memory controllers driven in lockstep.

The primary controller drives the address and command bus and 32-bits of the DQ bus, while the other controllers drive the remainder of the DQ bus.

The following table summarizes the supported lockstep configurations:

Table 3.  Supported Lockstep Controller Configurations
Memory Protocol Configuration DQ Width AXI Interface
DDR4 x40 40 256 b + 64 b USER DATA
DDR4 x64 64 512 b
DDR4 x64 with ECC 1 72 512 b
DDR4 x72 72 512 b + 64 b USER DATA

To ensure that the controllers remain coordinated in lockstep, the following points apply:

  • Lockstep configurations support only synchronous fabric clocking mode. NoC Mode is not supported.
  • Some of the controller scheduling and optimization features are disabled.
  • There are limitations on the types of AXI transactions supported. Refer to the following table for details.
    Table 4.  Limitations for Lockstep Configuration in ES Devices
    Memory Protocol Configuration Limitation
    DDR4 x72 Supports AXI transfer size= 6 only.
    DDR4 x64 AXI transfer size min = 1* (2 bytes).
    DDR4 x64 Supports 2-byte aligned transfers only.
    DDR4 x40 Supports AXI transfer size= 5 only.
    DDR4 x40 Support 32-bit aligned transfers only.

Two Controllers in Lockstep Within One IO96 Bank

The EMIF IP instantiates 2 controllers within one IO96 bank to support x40 configurations. The AXI bus is configured as 256-bits wide plus 64-bits of user data (WUSER/RUSER), to generate the required 320-bits of data to transfer a burst-of-8 of 40-bit DQ. The following table illustrates how the AXI WDATA/RDATA and WUSER/RUSER can be mapped to the DQ lanes.

Table 5.  Mapping of WDATA/RDATA & WUSER/RUSER in x40 Configuration
Transfer 0 1 2 3 4 5 6 7
WDATA/RDATA 31:0 63:32 95:64 127:96 159:128 191:160 223:192 255:224
DQ [31:0]
WUSER/RUSER 7:0 15:8 23:16 31:24 39:32 47:40 55:48 63:56
DQ [39:32]

This configuration can support only 3 address/command lane configurations, because there are only 8 byte lanes in one IO96 bank. The WUSER/RUSER signal is mapped to byte lane 7 (DQ lane with prefix s) in x40 configuration.

Table 6.  Supported Byte Lane Placement for x40 configuration
Scheme BL0 BL1 BL2 BL3 BL4 BL5 BL6 BL7
DDR4_AC_TOP DQ[4] DQ[3] DQ[2] DQ[1] AC1 AC2 AC0 sDQ[0]
DDR4_AC_BOT DQ[0] AC0 AC1 AC2 DQ[1] DQ[2] DQ[3] sDQ[4]

Two/Three Controllers in Lockstep Within One IO96 Bank

This configuration is supported only in DDR4. The EMIF IP instantiates two or three controllers across two adjacent IO96 banks for the configurations listed in the table below.

Table 7.  Supported 2/3 Controller Configurations in Lockstep
Configuration DQ Width AXI Interface Notes
x64 64 512b 2 controllers used.
x64 with ECC 72 512b 3 controllers used. ECC will be generated and checked by a soft IP block within the EMIF IP.
x72 72 512b + 64b USER DATA 3 controllers used.

For the x72 configuration, the AXI bus is configured as 512-bits wide, plus 64-bits of user data (WUSER/RUSER). The following example illustrates how you can map the AXI WDATA/RDATA and WUSER/RUSER to the DQ lanes. In this illustration, the WUSER/RUSER is mapped to the byte lane used for DQ [71:64].

The actual DQ lane to which the WUSER/RUSER is mapped depends on the address and command placement used. In each supported address and command placement scheme, the WUSER/RUSER is mapped to the DQ lane that has a prefix s (for example, sDQ0, sDQ4 or sDQ8). Refer to the following tables in the DDR4 Data Width Mapping topic, to identify the actual DQ lane used for WUSER/RUSER:

  • Supported Lockstep configuration for DDR4 x64
  • Supported Lockstep configuration for DDR4 x72 or x64 (with ECC)
Table 8.  Example Mapping of WDATA/RDATA & WUSER/RUSER in x72 Configuration
Transfer 0 1 2 3 4 5 6 7
WDATA/RDATA 63:0 127:64 191:128 255:192 319:256 383:320 447:384 511:448
DQ [63:0]
WUSER/RUSER 7:0 15:8 23:16 31:24 39:32 47:40 55:48 63:56
DQ [71:64]

The generated IP has 2 mem DQ ports, collectively labeled as mem_DQ0 and mem_DQ1. The mapping below shows how these 2 ports are grouped into one single wide DQ port:

Figure 4. 
Level Two Title