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t_alars's avatar
t_alars
Icon for New Contributor rankNew Contributor
2 years ago
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Logic elements utilization in FPGA

Hello All, I have an old design on cyclone 3 with Quartus 10 and the used logic elements (in ALMs) are 20k. Now, I migrate exactly the same design to Quartus 21 also I changed the FPGA to Cyclone V...
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  • Nurina's avatar
    Nurina
    2 years ago

    Hi Taha,


    Yes, with a large software jump I would expect differences in the project. Be it ALM usage or place & route or timing performance.

    This is because as the Quartus versions change the optimization algorithm also changes.


    I would suggest to also check for nodes that have been synthesized away. If your design is small enough, you can see it in the netlist viewers. It is easier to check in the warning messages too. Check for the below warning message

    "Warning (14320): Synthesized away node"


    Regards,

    Nurina


Nurina's avatar
Nurina
Icon for Regular Contributor rankRegular Contributor
2 years ago

Hello,


Have you checked for the tri-state nodes as mentioned in the warnings?

I'm not familiar with tri-state usage in Cyclone V, but here are some threads that you may find useful:

https://community.intel.com/t5/Intel-Quartus-Prime-Software/Warning-Tri-state-nodes-do-not-directly-drive-top-level-pins/td-p/213330#:~:text=FPGA%20devices%20don't%20support,not%20possible%20for%20internal%20nodes.

https://community.intel.com/t5/Intel-Quartus-Prime-Software/An-important-warning-confused-me-tri-state-nodes-do-not-directly/td-p/180090

https://community.intel.com/t5/FPGA-SoC-And-CPLD-Boards-And/How-to-tri-state-the-configuration-pins-after-configuration-with/td-p/731909


As for your PLL clock settings warning, here are some threads you may find useful. It just seems like there is issues with the constraints, I would suggest using derive_pll_clocks :

https://community.intel.com/t5/Programmable-Devices/How-to-deal-with-this-warning/td-p/76741

https://www.intel.com/content/www/us/en/support/programmable/articles/000074876.html


Regards,

Nurina