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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

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

I can no longer replicate the issue either. I tried creating a minimal project with two multipliers, one using hardware multipliers and one using logic elements. The results were identical.

Then, since I use 3 instances in my full design, I used one with hardware multipliers and two with logic elements. The results were identical.

So, for now, let's assume the problem is solved (at least until it fails again)!

Thank you for your help!