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A bug of LUT component?

Honored Contributor II

Platform: xp + dsp builder 9.1 sp2 + matlab R2010a 


The LUT component works well in simulink. When I generate VHDL files and use them in Quartus, its instance outputs only the first value, but never changes when the address input changes. 


I check the VHDL file, and find that a SCLR input linked to OPEN. But there is no options related to SCLR in simulink. I manually link SCLR with the same wire linked to ACLR. Then the LUT works. 


Is this a bug, or my improper usage of this component? 


My problem is that I have to modify code for every instance of LUT, every time I update MDL and autogenerated VHDL files.
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Honored Contributor II

i've seen this or something similar before. i'm fairly certain its fixed in newer versions 


try using the ROM block instead of the LUT. i don't think it had that problem 


i think the problem has to do with the output register of the LUT. try disabling it and using an external delay if the ROM doesn't work 


for future reference i think a couple of other blocks had problems with the output register so if your hardware doesn't match Simulink either update to recent software or take a look at post-fit netlists to see if you can see the register disappearing
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