^
Advanced Search

AR# 34137 MIG v3.3, Spartan-6 FPGA LPDDR - Drive strength selected in MIG is not properly set in the output design

Description

MIG v3.3 allows the following drive strengths to be selected for the Spartan-6 FPGA LPDDR design:

  • Full-Strength
  • Half-Strength
  • Quarter Strength
  • One-eighth Strength

There are two issues with these settings:

  1. While One-eighth is an optional setting defined by JEDEC, Micron does not support this option. The next release of MIG will remove the One-eighth setting.
  2. The corresponding Output Drive Strength parameter (Cx_MEM_MDDR_ODS) does not get set appropriately. This parameter is always set to "FULL" regardless of the selection in the MIG tool. This Answer Record details the steps towork around this issue.

Solution

To work around this issue, you need to manually change the Cx_MEM_MDDR_ODS parameter to the appropriate value.

Step 1

Open the top-level module ("example_design/rtl/example.top.v/vhd" or the "user_design/rtl/<comp_name>.v/vhd") and locate the Cx_MEM_MDDR_ODS parameters. Thereis a unique parameter for each controller in the MIG design.

  • localparam C1_MEM_MDDR_ODS = "FULL";
  • localparam C3_MEM_MDDR_ODS = "FULL";

Step 2

Change the "FULL" setting to the desired output drive strength.The supported settings are:

  • "FULL"
  • "HALF"
  • "QUARTER"

This issue is scheduled to be fixed in 12.1 ISE tools.


Actions

AR# 34137
Date Created 02/02/2010
Last Updated 05/19/2012
Status Active
Type Known Issues
Devices
  • Spartan-6 LX
  • Spartan-6 LXT
IP
  • MIG
Feed Back