Nexys2 suddenly stopped working with custom bit files

[fentonc]

I had been successfully working with a Nexys2 board using ISE 14.7 on a laptop running linux and using digilent adept utilities 2.2.1 to program it. After taking a break for a few days, I went back to work on it, and now the board no longer seems to successfully load my .bit files. To be clear, the 'done' light comes on, and the 'djtgcfg' utility says that it was successfully programmed, but no matter what design I try all I see is some dimly light 7-segment displays. I had previously had  a 1280x1024 VGA controller working, but now even a design that directly has button 0 connected to LED 0 does not generate any kind of signs of life from the board aside from the 'done' LED.

ISE doesn't generate any errors or warnings about unconnected pins (and I'm using the 'master UCF' file for the -500 part on my board provided by digilent), so I'm really at a loss for what could be going on.

To further confound things, I downloaded the self-test design that digilent provides with the board and was able to successfully program the provided bit file (and it behaved perfectly), so it would appear that the board is still in fine shape.

Any further debugging suggestions?

[xc6lx45]

Hi,

those are just generic things to try. I hope you'll get more specific advice from the official support.

is it possible that some obscure options in your ISE project or the constraints file have been changed? I'd try a new copy of the constraints file and download or create a project from scratch. Reinstalling ISE might be another thing to try, just to rule out the possibility that it got damaged.

I would get a different USB cable and port, even if the original bitfiles work with the one you've got.

[fentonc]

Okay, sanity has returned. It turns out I had used the GUI to add a timing constraint for my clock, and for some reason it had created a new UCF file that only contained that constraint and added it to my project. The project then contained two UCF files, but it was only mapping the one that just had the clock.

I merged things into a single UCB and everything started working again.

[jpeyron]

Hi @fentonc,

Glad to hear that you figured out the issue and have resolved it. Thank you for sharing what you did to fix the issue.

Cheers,

Jon