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Altera_Forum's avatar
Altera_Forum
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16 years ago

Cyclone III On-Chip Termination

Hi,

I was wondering if anyone had a tutorial or instructions on how to enable the on-chip termination for the Cyclone III? On the Altera website, they mention that it can be done via assignment editor>i/o standard but I don't see any mention to OCT when I select this. I tried following the instructions of another forum, mentioning to configure it through assignment editor>i/o features, but it requires both from and to values. If I leave the from values empty, I am left with a question mark. I was also told that it can be enabled from the pin planner, does anyone know how to do it this way?

9 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    You have to display the column "Output Termination" in the Pin Planner context menu under "Customize Columns".

    The respective Assignment Editor syntax has an empty "From" field, the pin name in "To" and "Output Termination" as the Assignment Name.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    So do I have to add the pin names to my design (in the top entity), even though I'm not actually using them in the code? If yes, what type of signal do I define them as?

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    to enable OCT option in pin planner, right-click anywhere in the pin assignment column> customize column> select "input termination" and "output termination" from "available columns" and bring those options to the right-hand side "show this column.." box.

    you will see the termination option in the pin planner pin assignment area.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    --- Quote Start ---

    So do I have to add the pin names to my design (in the top entity), even though I'm not actually using them in the code?

    --- Quote End ---

    What are you talking about? On-chíp termination (not reasonable with unused signals, I think) or weak pull-up resistors? The latter can be globally enabled for all unused pins which is the default setting with newer chips.

    Cyclone III has only limited OCT capabilities by the way. So you should better clarify, what you mean.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    --- Quote Start ---

    What are you talking about? On-chíp termination (not reasonable with unused signals, I think) or weak pull-up resistors? The latter can be globally enabled for all unused pins which is the default setting with newer chips.

    Cyclone III has only limited OCT capabilities by the way. So you should better clarify, what you mean.

    --- Quote End ---

    What I meant was that since I'm using the pins for on-chip termination, i.e. they are not receiving or sending signals, do I still have to define them in my top entity or just set them to OCT capabilities in the assignment editor?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Sorry, but I don't either understand which pins you are talking about nor what you want to achieve with them. Why do you think, you have to set on chip termination for unused pins?

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I was talking about the RUP and RDN pins. I've tied resistors to these pins to either VCC or gnd (as specified in the datasheets) so that I can use them for OCT. They will be matched to 50 Ohm resistors. How do I make sure that the pin planner doesn't use the RUP and RDN pins for other I/Os?

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Assign them yourself. Then the fitter won't have the opportunity to reassign them.

    Jake
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Usually, selection of OCT with calibration for at least one I/O would reserve RUP and RDN pins.