nSTATUS is sometimes asserted low during Agilex-F configuration when operating in PMBus slave mode

Hi Itzik,
 

Thanks for the details. Since the failure is repeatable after a fixed 4130 AVST_CLK cycles and happens before ALERT, this points to the AVST configuration stream rather than PMBus.

 Could please try the following?

Raise AVST_CLK and verify VALID/READY handling
Use a faster AVST clock (target ≥1 MHz). Keep AVST_VALID high while streaming; when AVST_READY goes low, send idle clocks with VALID=0. Capture AVST_CLK, AVST_VALID, AVST_READY, and data around the 4130‑cycle point. This fixed similar stall-at-a-fixed-count cases. https://community.altera.com/discussions/boards-and-dev-kits/agilex-3-avst-programming-fails/122255

Read SDM status immediately after nSTATUS drops
Use the AN‑936 method or Configuration Debugger to read SDM major/minor codes right after the failure. It will tell whether the drop was due to AVST stream, PMBus, or another SDM check, guiding the next fix. KDB: [community.altera.com]

Regards,
Fakhrul
 

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