When you implement the DDR3 SDRAM Controller with UniPHY in a MAX® 10 device and add pin location assignments to the DQSn pins in the QSF file, you may get following fitter error.
Error (165011): altmemphy pin placement was unsuccessful
Error (13130): The assigned location PIN <pin_number> for DQSn pin mem_dqs_n[*] is not a legal location
As DQSn is a pseudo differential pin of DQS, a pin location assignment for DQSn is not needed. The pin location assignment on the DQS pin is sufficient.