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AR# 50615

MIG Spartan-6 v3.91 LPDDR - Incorrect Termination upon Reset

Description

Issue Found: v3.91
Issue Resolved: v3.92 (available with ISE 14.2)

The MIG Spartan-6 LPDDR design has been found to incorrectly turn on n-term termination during consecutive resets. This issue is specifically seen when the PLL output clocks sys_clk2x (CLKOUT0) and drp_clk (CLKOUT3) have a 2:1 ratio. The associated failure is a continued decrease in DQS/DQ amplitude after each reset. This eventually results inthe I/O (and therefore MCB) not capturing reads. Failures can be seen during calibration (calib_done does not assert). An exampleof the amplitude decrease is shown below.

50615.JPG
50615.JPG


Solution

MIG v3.92 includes updated soft calibration code which prevents the incorrect enabling of n-term. Before the release of v3.92 or for customers not wanting to upgrade to the latest MIG code, the updated mcb_soft_calibration module and readme can be downloaded from the bottom of this answer record. It is a drop-in replacement for the MIG generated mcb_soft_calibration module located in both the "example_design/rtl/mcb_controller" and "user_design/rtl/mcb_controller" directories.

Attachments

Associated Attachments

Name File Size File Type
ar50615.zip 15 KB ZIP

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
50642 MIG Virtex-6 and Spartan-6 v3.92 - Release Notes and Known Issues for ISE Design Suite 14.3 N/A N/A
AR# 50615
Date Created 07/02/2012
Last Updated 03/02/2013
Status Active
Type Known Issues
Devices
  • Spartan-6
  • Spartan-6 LX
  • Spartan-6 LXT
  • Spartan-6Q
IP
  • MIG Virtex-6 and Spartan-6