Honored Contributor
Honored ContributorI have resolved my issues. May be my findings help some one else in the future.
The address send by the EPCQ controller was correct in the SPI mode: The hardware only stores the 24 most significant bits of the address, and then transmits 0 for the least significant byte. This is what is described on page 8-38 of the device handbook: https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/hb/arria-v/av_5v2.pdf Why there is a mismatch in address mode even though the Factory configures well. The answer is the default boot loader. Even though there is an NVCR corresponds to the 4 BYTE Address Mode, the operation code 4BYTEARREX (EPCQ 256 Datasheet) overrides this value. I have observed the presence of 4BYTEARREX in SPI interface when the default boot copier runs. So the solution is to force the EPCQ256 device in 4BYTE ADDRESS MODE before reconfig either by epcs_enter_4_bytes_mode call or some other method.
