Have you double-checked your clock signal when this occurs? I ran into a similar problem with a Spartan 3; the clock signal was bad, and the DCM couldn't deal with it and stopped clocking the chip.
I never had it come back on its own, though. Maybe your clock is noisy, so the DCM occasionally gets confused, and then starts working again. Matthew On Nov 17, 2010, at 11:40 AM, Laura Spitler wrote: >> Maybe it's overheating? Do you have a little fan right on the FPGA? >> We've found that is necessary, even in a "proper" case. We cut a hole in >> the lid and add a fan right over the chip. > > Interesting idea. I do have a small fan attached to the iBOB heat > sink. It was running at the time. The iBOB is mounted in a rack with > plenty of ventilation. > One other point that just occurred to me... the 8 small LEDs > accessible from the fabric were off, but the larger LED that indicates > that the fabric is programmed was ON. Not sure if that helps support a > diagnosis of the FPGA overheating. > >> That, or a power supply regulator is overheating and shutting down. >> might be able to diagnose that with your finger. (carefully, as they run >> somewhat hot anyway!) > > Hmm... Would a power supply regulator overheating cause the FPGA to > lose it's programming? When it comes back to life it returns to normal > with its software registers set correctly and everything. > > Laura > > >> >> John >> >>> Thanks, >>> Laura >>> >> >> >>
