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I see there is a global "slow slew rate" option.
Is it possible to turn it on for individual pins, using Tcl scripting? If so, how? If not, I guess I could turn it on globally; how much would I need to adjust timing for memory devices? (IOW - What is the difference in slew rate between "fast" and "slow"?)Link Copied
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Hi Jason,
You can do this in Quartus with the assignment editor: Assignments->Assignment Editor menu item Category: Logic Options: I/O Timing Then: "To" column: select the pin (you can do this via Node Finder) "Assignment Name" column: Slow Slew Rate Regards, --Scott- Mark as New
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Thanks Scott.
Turning on "slow slew rate" didn't make much of a difference. I explored a bit further and discovered the current limit control - Assignment Editor - Logic Options - I/O Features - Assignment Name "Current Strength" - Value "Minimum Current". The "output pins" section indicates the current limit changed to 4mA (was 24mA). Using this reduced signal products around 50-100 MHz by 3dB. Slugging the output pin with 33pF further reduced those signal products by a further 3dB, and "eradicated" those above 100MHz. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/biggrin.gif
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