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t_alars's avatar
t_alars
Icon for New Contributor rankNew Contributor
3 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
    3 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
3 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


  • t_alars's avatar
    t_alars
    Icon for New Contributor rankNew Contributor
    3 years ago

    Hello @Nurina ,

    I got this after all the compilation complete(no error, or critical warning), I believe the design is good, but I want to double-check with you for the last time.

    Do You think it is fine?

    Thank you so much for your support.

    • FvM's avatar
      FvM
      Icon for Super Contributor rankSuper Contributor
      3 years ago
      Hi,
      the basic point wasn't yet mentioned. Cyclone III (respectively IV or 10) LE is a completely different metric than Cyclone V ALM. Cyclone III LE has one 4-input LUT, ALM has two 6-input LUTs. Effectivity of 4- versus 6-input LUTs is different depending on the complexity of logic or arithmetic operations. Therefore it's difficult to define a general factor.