Due to an incorrect receiver common mode voltage (Rx Vcm) setting in Quartus® II software version 14.0 and earlier, the PCI Express® signal detect feature may fail at low temperatures on Arria® V GT and ST devices, and the link fails to train.
The table below shows the Arria® device VCCR_GXB and Rx Vcm requirements.
| Device | VCCR_GXB Voltage | Rx Vcm Voltage |
| Arria V GX, SX | 1.1V/1.15V | 0.65V |
| Arria V GT, ST | 1.2V | 0.75V |
To work around this problem in Arria® V GT and ST devices, you can download and install the patch below and add the following Quartus® II Settings File (QSF) assignment for all PCI Express receiver channels in your design.
- Download the Quartus II software version 13.1 patch 0.110 for Windows (.exe)
- Download the Quartus II software version 13.1 patch 0.110 for Linux (.run)
- Download the Quartus II software version 13.1 patch 0.110 Readme file (.txt)
set_instance_assignment -name XCVR_RX_COMMON_MODE_VOLTAGE VTT_0P75V -to <pin_name>
You must make the above assignment to all PCI Express receiver pins in your design, and you should not use wildcard characters (*) in your assignments.
This problem has already been fixed in the Quartus® II software version 15.0.