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Altera_Forum's avatar
Altera_Forum
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12 years ago

Cyclone V LVDS differential termination

In the pin planner I specified input termination as differential for LVDS inputs.

Do I need to specify for both positive and negative signals or just one?

It seems to work both ways which bothers me.

Thanks

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    --- Quote Start ---

    you may check the fit report for those two ways

    --- Quote End ---

    Looks like that helped.

    If I only assign termination to the positive then both positive and negative termination are off in the fitter report.

    So it appears you have to assign termination to both positive and negative in the pin planner.

    Thanks
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    Sounds unlikely. Up to now, the basic method with differential I/O standards has been to assign the non-inverted pin and also specifiy additional I/O features for thi spin.

    The pin planner tool is primarly a wrapper around the pin assignments, but does some things on it's own by e.g. displaying the inverted pins along with the (primarly assigned) non-inverted pins.

    In case of doubt, I would check the actual pin assignments, in assignment editor or *.qsf file.