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AR# 31735

MIG v2.3 - MIG tool does not allow selection of Reduced Strength for the Extended Mode Register Output Drive Strength setting


MIG v2.3 does not allow changing the Output Drive Strength Extended Mode Register setting from Full Strength to Reduced Strength for the Spartan-3 DDR, Virtex-4 DDR/DDR2 Direct Clocking, Virtex-4 DDR2 SERDES, and Virtex-5 DDR designs. This should be selectable as it is for other MIG designs such as Virtex-5 DDR2.


Thisissue isfixed in MIG v2.4.

As per memory specifications, EXT_LOAD_MODE_REGISTER[1] i.e., EMRS[1] corresponds to Output Drive Strength.

EMRS[0] = '0' FULL Drive Strength

EMRS[1] = '1' Reduced Drive Strength

To work around this issue, modify the top-level parameter for the specific design as follows:

Virtex-4 and Spartan-3

Change the value of the "EXT_LOAD_MODE_REGISTER" parameter in the parameters.v/.vhd file. For example, Output Drive Strength value of Fullstrength in the MIG output is as follows:

'define EXT_LOAD_MODE_REGISTER 13'b0000000000000

To make it Reduce drive strength change the EMRS[1] value to '1':

'define EXT_LOAD_MODE_REGISTER 13'b0000000000010


Change the top-level parameter "REDUCE_DRV" from 0 to 1 in the ddr2_sdram.v/.vhd file to set Reduced Drive Strength.

AR# 31735
Date 12/15/2012
Status Active
Type General Article
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