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AR# 24645

MPMC2 v1.7 - Virtex4 reads from DDR/DDR2 always reads as 0xFFFFFFFF

Description

After power-up the contents of DDR2 memory using the MPMC2 always reads as 0xFFFFFFFF. What are some steps to debug this problem?

Solution


There are a couple of reasons why the contents of memory can read 0xFFFFFFFF.



* IDELAYCTRL may not be instanced in the correct clock region

* Read calibration window my be shifted by half or one clock cycle



IDELAYCTRL

* Please refer to answer record IDELAYCTRL (Xilinx Answer 25147)

* Also look at (Xilinx Answer 24644)



READ Calibration

* Look at (Xilinx Answer 24657)
AR# 24645
Date Created 01/31/2007
Last Updated 11/12/2010
Status Archive
Type General Article