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Altera_Forum
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15 years ago

How to switch on "weak pullups" for Cyclone in Quartus 10SP1

Hello,

I am doing a development using a Cylclone EP1C3T100.

I am using Quartus 10 SP 1

My design needs a few DIP switches, and so I thought that I can use the internal pull-ups to get the high level. But I cannot configure them in Quartus.

1. Try: I use the Ressource Property Editor, I then select "Weak Pull Up" and set it to "ON". I then run "Edit"->"Check Ressource Properties" and it becomes accepted and printed bold. But when I then look into the synthesis result files, "Weak Pull Up" for the pin is OFF and also it is off if looking into the ressource properties afterwards.

2. Try: I generally switch weak pullups using "Assignments"->"Settings"->"Fitter Settings"->"More Settings..." and there at the very bottom is also a "Weak Pull Up" selection. If I turn on this, I get a fitter error:

Error: Can't place I/O pin osc_clk at pin location 10 -- I/O pin uses weak pullup, which is not supported by this pin location

For methode# 2 I did not find how to turn off the weak pull up on Pin 10, all selections in the property editor are greyed out.

Any idea how to solve this? I would like to save the external pull up resistor.

Thanks a lot in advance, Günter (dl4mea)

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    Can't place I/O pin osc_clk at pin location 10 -- I/O pin uses weak pullup, which is not supported by this pin location

    --- Quote End ---

    Yes it's true. Pin10 is a dedicated clock input. Weak pull-up isn't supported for clock pins, only for general I/O pins.
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Hello,

    thanks for the confirmation. But how can I reach my goal of having the weak pullups active on the switch inputs?

    Cheers, Günter
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    I didn't clearly understand from your post, if the reported problems have been with other pins than CLK0 (pin 10). With other pins, weak pull-up should work of course. But the resource property editor isn't the right way to do it, it's only intended for changes to a compiled design. You have to use either the assignment editor or the convenient pin planner. Columns showing the respective properties can be enabled in the pin planner.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    can be enabled in the pin planner.

    --- Quote End ---

    Hello,

    thanks for the answer.

    Even if it sounds foolish, can you please tell me the details steps how to enable a weak pullup in a EP1C3 device in pin planner? I had a look at all the options, but did not find the one that gives me this option. Some of the configurations in Quartus are really behind a labyrinth.

    Thanks, Günter
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    As said, you have to enable the weak pull-up resistor column. It's done by the "Customize Columns" function in the context menu.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    It's done by the "Customize Columns" function in the context menu.

    --- Quote End ---

    Hello FvM,

    thanks a lot for your comment, now I got it. As I said, Quartus is a labyrinth of configuration options.

    Thanks again, Günter