Type: Answers

Area: EMIF

Area: Intellectual Property


IP Product: DDR3 SDRAM Controller Supporting UniPHY

Why are there duplicates for the differential signals in the Pin Planner after I run the <variation name>_pin_assignments.tcl file?

Description

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_dqs and mem_dqs(n)
  • mem_dqs_n and mem_dqs_n(n)
  • mem_ck and mem_ck(n)
  • mem_ck_n and mem_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.

Workaround/Fix

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.