Critical Issue
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.