Rd, OCT Default Value in LVDS

[richwright]

I am using an Arria 10 GX device. There are a number of pins using LVDS IO standard.  The Termination has been set in Pin Planner to Differential but the "Receiver On Chip Termination" has not been specified. I cannot find any documentation that tells me what the compiler does with the On Chip resistance, Rd, if the value is not specified. There three values to choose from 85 ohm, 100 ohm, and External Termination.

I can see that the GSF adds lines of code when this parameter is changed in Pin Planner:

set_instance_assignment -name XCVR_A10_RX_TERM_SEL R_R1 -to ICBS_1_P

set_instance_assignment -name XCVR_A10_RX_TERM_SEL R_R1 -to "ICBS_1_P(n)"

I have not seen much noticeable change in signal at this receiver when I change this value. Perhaps the default is what I am setting.

Can anyone tell me what is the default value and show me where that is documented? 

Is there any possibility that something , like a Global parameter or anything else, that can override the Receiver On Chip Termination (Rd)?

Note: I have already looked at the Intel® Arria® 10 Core Fabric and General Purpose I/Os Handbook. Nothing about default values are mentioned.

Thanks in advance to all.

Rich

[EngWei_O_Intel]

Hi Rich

If you refer to 

https://www.intel.com/content/www/us/en/programmable/documentation/nik1398707230472.html

parameter is meant for usage of transceiver.

For LVDS GPIO, you can do the setting through Assignment Editor, or manually using the INPUT_TERMINATION assignment as mentioned in 

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/manual/mnl-pro-qsf-reference.pdf

Thanks.

[richwright]

Thank you very much for this response. Can you tell me about the default termination value if the INPUT_TERMINATION is set to DIFFERENTIAL in Assignment editor but no termination value is specified by the designer?

[EngWei_O_Intel · Accepted solution]

Hi there

By checking on https://www.intel.com/content/www/us/en/programmable/documentation/sam1403483633377.html#sam1403482197912

The Rd OCT shall be of 100 ohm.

[richwright]

Even resource view shows no specification. How do we know what we are matching on the board trace?

[richwright]

Shouldn't this value exist somewhere in the Resource Property Editor or Technology Map Viewer?

[EngWei_O_Intel]

Hi there

I am not fully confirm about its appearance in any viewer. But the setting shall be visible in fitter report.

Thanks.

Eng Wei