Knowledge Base Article
Can I use the programmable differential on-chip termination (OCT) 85-. setting in Cyclone® IV GX devices?
Description
No, you cannot use differential OCT 85-. even though the ALTGX Intel® FPGA IP in the Intel® Quartus® II software version 10.0 and 10.0 SP1 has this setting in the pull down menu for Cyclone® IV GX devices. This is applicable to both receiver and transmitter variations.
Resolution
If the 85-. setting is selected in the ALTGX receiver Intel FPGA IP, no warning will be displayed. The termination value assigned to the device will be differential 100-. However, if you select the 100-. setting in the ALTGX receiver Intel FPGA IP, you will get the following warning during compilation in the Intel Quartus II software, which can be safely ignored:
“MGL_INTERNAL_WARNING: ( The parameter value is not one of the pre-specified values in the value list.) alt_c3gxb|receiver_termination The value assigned is oct_100_ohms and the valid value list is OCT_85_OHMS|OCT_150_OHMS”
If the 85-. setting is selected in the ALTGX transmitter Intel FPGA IP, you will get the following warning message during compilation in the Intel Quartus II software. The termination value assigned to the device will be differential 100-:
“MGL_INTERNAL_WARNING: ( The parameter value is not one of the pre-specified values in the value list.) alt_c3gxb|transmitter_termination The value assigned is oct_85_ohms and the valid value list is OCT_100_OHMS|OCT_150_OHMS”
These warning messages are discussed in detail in the Quartus II Software Version 10.0 Release Notes (PDF).
This issue will be fixed in a future version of the Intel Quartus II software.