On 9/06/2012 5:45 AM, Bil Herd wrote: > I have seen Xylinx parts not work at speed, as in internal noise, ultimately > Xylinx admitted that there were problems. This was some of their big > expensive parts that ultimately couldn’t be "loaded up and ran" as this wasn’t > not a subtle problem where you track down a glitch, whole sections > propagated invalid states. [pedantic] Xilinx, not Xylinx [/pedantic] Wonder if it was SSN (simultaneous switching noise)? When large portions of a device change state at the same time, it momentarily pulls a lot of current and also produces noise that can effect other parts of the device. It's something you need to be mindful of even in "non-faulty" devices, but it sounds like they had more than normal problems with it!?! I have a design that has been running on 4 different Altera devices; Cyclone, Cyclone II, Cyclone III & Startix III. Involves a rather wide mux and is scalable. On the Stratix III I have it running up to 64 inputs side. Even on the lower-end Cyclone II it handles at least 16 inputs. On Xilinx devices it craps out after 8 inputs. And if you try more, the synthesis runs forever!!! Regards, -- | Mark McDougall | "Electrical Engineers do it | <http://members.iinet.net.au/~msmcdoug> | with less resistance!" Message was sent through the cbm-hackers mailing listReceived on 2012-06-09 02:00:04
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