Re: How to activate LVDS Rd OCT for Arria II GX

Altera_Forum · ‎03-11-2011

Good morning,

Can somebody help me, I don't seem to be able to assign 100ohm Rd OCT input termination logic option in assignment editor. All Arria II GX documentation I have seen indicate that for DIFFIO_RX pairs it is possible to activate receiver 100ohm OCT termination.

So, I defined an adc[11:0] input pin array in the top level Verilog module, assigned LVDS as an I/O standard for those pins, assigned adc[0] pin to PIN_A18 location (adc[0](n) went to PIN_A17) and then added the following assignment: To: adc[0], Assignment name: Input Termination, Value: OCT 100ohms, Enabled: Yes, Entity: Arria (my top level verilog module name).

Now, when I compile it, Quartus complains that: "Error: I/O pin adc[0] with Termination logic option setting OCT 100 Ohms cannot be assigned to pin A18 -- pin does not support logic option setting" and "Error: I/O pin adc[0](n) with Termination logic option setting OCT 100 Ohms cannot be assigned to pin A17 -- pin does not support logic option setting". Yet the pair A18/A17 is named DIFFIO_RX_T31p/n which should support OCT 100ohms.

Moreover, when I remove the location assignment of this pin and let the fitter look for a place to assign this pin, it can't. It tries all DIFFIO_RX pins and gives the same error message for all locations it tries.

So, how am I supposed to activate Rd OCT for LVDS input pairs then? Or is 100ohm LVDS input termination automatically activated for all LVDS pairs that I assign to DIFFIO_RX locations? I need to know this before I send the board in for manufacturing.

I am running Quartus II 10.0sp1 and the selected FPGA is EP2AGX95DF25C5.

I'll be very thankful for any response you guys can give me. I have so far worked with Cyclone III series and this is my first Arria II based design.

Altera_Forum · ‎03-11-2011

If the I/O features syntax hasn't changed with Quartus 10, the correct assignment is still differential input termination rather than OCT 100 ohm. It has to be applied to the non-inverted input signal.

Altera_Forum · ‎03-11-2011

Thanks! :)

Quartus is deffinitely happy with this assignment. Sorry about such a newbie question then. Cyclones I worked with before didn't have input termination anyway.