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Assigning unused pins in Quartus II

Hi folks

I have a VHDL design which I'm putting on an FPGA with Quartus II. There is a specific pin on the FPGA which I need to drive high. This pin has no corresponding port in my VHDL file and I don't want to edit the VHDL file.

I can find the option in Quartus to assign all unused pins to say "driving low." However I want to keep the default at "driving low" while assigning just this pin to "driving high."

The reason for this is that the default drving low value causes the configuration controller on my dev-kit (NiosII Stratix kit) to reconfigure repeatedly.

How can I assign just one pin to drive high? I'm certain it can be done, but for the life of me I cannot find the option in Quartus.

Thanks in advance, Richard

Reply to
rnbrady
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This is one of the most mind boggling things about Quartus II. By default it set all unspecified pins to ground, which is a terrible default as one quick first test is likely to miss this and will end up driving ground to a bunch of should-be input pins.

Richard, the fix for you problem is (from memory) to enter the general settings (assignments?) and change the pin default from "output driving ground" to "input tristated". That should solve this problem completely.

Tommy

Reply to
Tommy Thorn

The Unused Pin Option setting is in: Assignments Settings->Device->Device & Pin Options->Unused Pins.

H> rnbrady wrote:

Reply to
Subroto Datta

Just out of curiousity, why don't you want to edit the VHDL file since apparently 'as it is now' the design is somewhat deficient in that it doesn't do what you want it to do.

KJ

Reply to
KJ

Thanks Subroto.

Do you know why this isn't the default?

Regards, Tommy

Reply to
Tommy Thorn

The choice of unused pins driving low was used I believe to improve signal integrity. However I am not an expert in this area, but I do know that several customers have mentioned this to be a confusing choice. The default will change with future device families.

- Subroto

Reply to
Subroto Datta

The VHDL file is autogenerated, and I feel that editing it with specifics about the precise target board is a hack. To me this should reside in a separate file or be programmable via the GUI.

Reply to
rnbrady

It's not the default I'm looking for, but rather a setting for individual pins to ovverride the default. To me it is unreasonable to assume all unsed pins should have the same behaviour. It would make more sense to allow the assignment editor to override the default for a given pin.

Thanks for your reply, Richard

Reply to
rnbrady

Spot on! I don't know why I didn't think of doing this. There is obviously an external pull-up resistor on that pin.

Thanks a ton Tommy, and thanks to everyone for the help!

Richard

Reply to
rnbrady

If it's auto-generated, it can be auto-hacked. Just write a script in your favorite language to do whatever needs doing and toss that into your Makefile.

(That's not to discourage easier solutions. I'm just trying to say that you shouldn't avoid hacking the "source" code because you don't think of it as source code.

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Reply to
Hal Murray

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