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Altera_Forum
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13 years ago

Constraining SDRAM

Hello, I have a very strange issue on my EP3C55F484, when sometimes Nios II processor works, sometimes - not. One minute I am able to upload the binary, it works fine for a half of a day even if I...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

I did try with -1ns, but that didn't help.

I am observing interesting thing. I've routed sys_clk signal to debug output pin and set the PLL phase difference between sys_clk and sdram_chip_clk to -6ns. The scope shows me, that the difference between these two signals is -3.2ns. I didn't check that before, but if there's such a huge difference, then I believe I had way much smaller phase difference, when used PLL settings for -3ns. So far, the design is working fine with -6ns @ PLL settings, but as You may know, I still see problems in TQ. Maybe adding max delays will help.