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20707 Discussions

Weak pull-up setting is ignored

Altera_Forum
Honored Contributor II
1,923 Views

Hi, please help me with this issue. I am stuck with enabling weak pull-up on the I/O pins. I set whole bus's defined by the location earlier weak pull-ups to ON, but fitter ignores it. How to do it properly? I read about constraints, but they should not apply here!

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Altera_Forum
Honored Contributor II
370 Views

Don't know what you did exactly. Programmablé (weak) pull-up can be enabled in the Pin Planner or Assignment Editor.

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Altera_Forum
Honored Contributor II
370 Views

I'm not sure what you mean by "the fitter ignores it" but the pullup may be weaker than you think. Try using the Assignment Editor to assign "Passive Resistor" which can be pulled either up or down.

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Altera_Forum
Honored Contributor II
370 Views

Passive resistor option: quartus help says "This option is used in functional simulations only". 

Is there any way to _physically_ pull up the signal other than weak pull-up (which seems to be insufficient) and external resistor (which is another device on the board)?
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Altera_Forum
Honored Contributor II
370 Views

Be sure to have your pins as INOUT or IN. Setting "weak pull-up" in the assignment editor has always worked for me.

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