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K_Crocker's avatar
K_Crocker
Icon for Occasional Contributor rankOccasional Contributor
1 year ago
Solved

LPM_MULT not working for Cyclone 10 GX device

I can't get a simple LPM_MULT instantiation to work. It simulates fine in Questa, synthesizes in Quartus Prime 24.2.0 Build 40 06/27/2024 SC Pro Edition without warnings, but 'result' is always 0 wit...
Fpga Devkit
  • K_Crocker's avatar
    K_Crocker
    1 year ago

    I could strip down the design, but I have some new information. I was able to work around the issue by changing the implementation style to "Use logic elements", in lieu of "Use the default implementation" or "Use the dedicated multiplier circuitry". I believe the default implementation is to use the dedicated multiplier circuitry. I think there really is a bug in the Altera LPM_MULT IP when using multiplier blocks.

    Changed to "Use loigc elements"Signal Tap showing ckt works as expected

ShengN_altera's avatar
ShengN_altera
Icon for Super Contributor rankSuper Contributor
1 year ago

Hi,


So you able to tap correctly with just LPM_MULT IP?


Thanks,

Regards,

Sheng


  • K_Crocker's avatar
    K_Crocker
    Icon for Occasional Contributor rankOccasional Contributor
    1 year ago

    If lpm.hint is "DEDICATED_MULTIPLIER_CIRCUITRY=NO,MAXIMIZE_SPEED=5" multiplier operates nominally.

    If lpm.hint is "MAXIMIZE_SPEED=5" multiplier always outputs 0 for my FPGA (10CX150YF780E6G).