Type: Answers, Errata

Area: EMIF, Intellectual Property



Error Message Citing Different I/O Standards for DQ I/O and DQS I/O Pins

Description

This problem affects DDR2, DDR3, LPDDR2, QDR II, RLDRAM II, and RLDRAM 3 products.

When compiling your memory interface, you might receive warning messages resembling the following:

DQ I/O pins fed by DQS I/O pin "I/O pad mem_dqs[n]" assigned different I/O standards -- it is recommended that all DQ I/O pins fed by the same DQS I/O pin have the same I/O standard

Workaround/Fix

If you receive this warning message, check that the DQ I/O pins associated with the warning are set to SSTL-15 CLASS I, and that the DQS pin is set to DIFFERENTIAL 1.5-V SSTL CLASS I. If the pins are set as described, the warning is false and can be ignored.

This issue will be fixed in a future release.