Device Family: Cyclone® V

Type: Answers, Errata

Area: EMIF, Intellectual Property

Some DQ Group Locations Are Not Usable in Cyclone V


In Cyclone V, you may encounter one of the following error messages when trying to place a DQ group:

Could not place DQS group fed by DQS I/O pad mem_dqs Illegal constraint of DQS group fed by DQS I/O pad mem_dqs

This issue occurs when you attempt to place a DQ group at any of the following I/O locations:

X2Y0 X2Y81 X4Y0 X4Y81 X6Y0 X6Y81 X79Y81 X81Y81 X83Y81 X85Y81 X89Y3 X89Y4 X89Y5 X89Y6 X89Y71 X89Y72 X89Y73 X89Y74 X8Y0 X8Y81

This issue affects all protocols targeting Cyclone V devices. This issue will be fixed in a future version of the software.


The workaround for this issue is to avoid assigning DQ groups to the affected locations; if no other DQ group locations are available, use a larger device.