Due to a problem in the Quartus® II software Pin Planner tool, some differential signals may appear twice in the Pin Planner for the UniPHY-based memory controller. For example, mem_dqs(n) and mem_dqs_n(n) as well as mem_ck(n) and mem_ck_n(n) signals may appear after the <variation name>_pin_assignments.tcl is run. The Pin Planner may also show the following pins as differential pairs:
mem_dqsandmem_dqs(n)mem_dqs_nandmem_dqs_n(n)mem_ckandmem_ck(n)mem_ck_nandmem_ck_n(n)
This duplication occurs because the <variation name>_pin_assignments.tcl file sets the IO_STANDARD assignments as DIFFERENTIAL for these signals. The Pin Planner then automatically creates a negative pin for these signals.
There is no workaround necessary for this problem. After the positive pin location is assigned, the Pin Planner will correctly assign the negative pin of the differential pair. After the Fitter is run, it will show up correctly in the Pin Planner.
This problem will be fixed in a future version of the Quartus II software.