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How to set up PULL UP resistor in Spratn 3?

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EDA_hg81

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I have defined the IO pad be pulled up in UCF file like following:

Code: 
NET "INDATA" PULLUP;

But it does not work.

How should I to modify?

Should I write sth in code?

Thanks.
 

I use to assign pull-ups by going to ASSIGN PINS option and set the IO pin to "pullup"...But it simply adds PULL UP in your user constraint file like you said. It has worked for me....I too have used spartan 3.check your hardware one more time....
 

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    EDA_hg81

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Thank you.
I think there have some bugs in my code.
 

I typically use statements like this in my UCF file, and the pullup works fine:
NET "SIO3" LOC="P92" | IOSTANDARD=LVCMOS25 | PULLUP;
 

use this constraints in UCF
net "pin Name" PULLUP; or u can use fpga editor to modify the pull up.
 

I would rather prefer PACE to do these things. HI Echo, What does this mean "IOSTANDARD=LVCMOS25 "?.....I never came across such thing. I just have used PULL UPS next to the loc in ucf. Never received any errors.
 

IOSTANDARD is an optional constraint that selects the desired I/O signal standard. LVCMOS25 means 2.5 volt CMOS. See the Spartan-3 data sheet, Table 2, "Signal Standards Supported by the Spartan-3 Family".

Each I/O buffer provides additional options such as slew rate and drive strength . Those two are very helpful for fine-tuning signal quality when driving long PCB traces. The various options are described in the data sheet, user guide, and ISE Constraints Guide. They are easy to put into the UCF file, like this:
NET "TXEN" LOC="B17" | IOSTANDARD=LVCMOS18 | SLEW=FAST | DRIVE=4 | PULLDOWN;
 

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