Forum Discussion

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

CDC-50001 - 1-Bit Asynchronous Transfer Not Synchronized

the Quartus STA reports "CDC-50001 - 1-Bit Asynchronous Transfer Not Synchronized" sync-fifo in my design . at this document "AN 919: Improving Quality of Results with Design Assistant" :https://...
Timing
sstrell's avatar
sstrell
Icon for Super Contributor rankSuper Contributor
1 year ago

Quartus may not be recognizing these registers as a synchronization chain.

What are your synch chain length settings (Compiler Settings -> Advanced Synthesis) and synchronizer identification settings (Timing Analyzer -> Metastability Analysis tab)?

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

    I think it is 3 ? / is it the right option ? and auto ?

    • sstrell's avatar
      sstrell
      Icon for Super Contributor rankSuper Contributor
      1 year ago

      Since it's set to 3 and you only have 2 registers in the destination clock domain, it's not getting recognized as a synch chain. Add an extra register or reduce the chain length, though I'd recommend adding a register because it is much more common to have 2 registers in a row throughout your design so there would be a better chance of chains getting mis-identified.