Device Family: Cyclone® V GT

Device Family: Cyclone® V ST

Type: Answers

Area: HSIO

Last Modified: April 13, 2017
Bug ID: FB: 386594;

Why might the PCI Express configuration fail link training at low temperature for Cyclone V GT and ST devices?


Due to a problem in Quartus® Prime software version 17.0 and earlier, you may observe PCIe Signal Detect (SD) circuit unable to assert or switch “ON” at low temperature.  Please check Cyclone® V Errata sheet for more details.


To work around this problem in Cyclone V GT and ST devices, make the following changes:

Add the following Quartus Prime Settings File (QSF) assignment for all PCI Express receiver channels in your design. 

  • set_instance_assignment -name XCVR_RX_COMMON_MODE_VOLTAGE VTT_0P70V -to <pin_name>
  • set_instance_assignment -name XCVR_RX_SD_THRESHOLD 5 -to <pin_name> 

Include the above assignment to all PCI Express receiver pins in the design and do not use wildcard characters (*) in the assignments.

However, Quartus Prime software version before 17.0 will not allow fitter compilation with the above QSF assignment. Hence, please contact MySupport for a patch.