Article ID: 000076841 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Can I use the programmable differential on-chip termination (OCT) 85-. setting in Cyclone IV GX devices?

Environment

  • Cyclone® IV GX FPGA
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Description

No, you cannot use differential OCT 85-. even though the ALTGX megafunction in the 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.

 

If the 85-. setting is selected in the ALTGX receiver megafunction, 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 megafunction, you will get the warning below during compilation in the 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 megafunction, you will get the warning message shown below during compilation in the 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 Quartus II software.

 

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