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AM625: Serial NAND boot Chip-Select

Koichiro Tashiro
Mastermind 22945 points
Part Number: AM625


Hi,

I got a question from my customer. He wants to know how CS signal is selected in Serial NAND boot.
According to TRM, section 5.4.10 Serial NAND Boot, it is not clearly described which CS signal can be used / selected.

TRM Table 5-4 Primary Boot Mode Selection shows there is "Csel" configuration for  OSPI / QSPI /SPI, but not for Serial NAND.



And TRM table 5-37 shows OSPI0 signals are used for Serial NAND, but "OSPI boot" and "Serial NAND boot" are different boot modes.
It is confusing. Could you clarify the differences of these two boot modes?


Thanks and regards,
Koichiro Tashiro 

  • +1
    TI__Guru 70182 points

    Hi Tashiro-san,

    Koichiro Tashiro said:
    TRM Table 5-4 Primary Boot Mode Selection shows there is "Csel" configuration for  OSPI / QSPI /SPI, but not for Serial NAND.

    If there's no Csel configuration shown for a given boot mode that means a default Csel of 0 is used, and that it is not configurable. I just confirmed this behavior with the boot ROM source of AM625x to make sure.

    Koichiro Tashiro said:
    And TRM table 5-37 shows OSPI0 signals are used for Serial NAND, but "OSPI boot" and "Serial NAND boot" are different boot modes.
    It is confusing. Could you clarify the differences of these two boot modes?

    The HW interface / peripheral module is the same ("OSPI"), so that's how the signals/pins are named. As for OSPI boot vs. NAND boot the difference is in the protocol. One good example of this is if you look at the schematic of the SK-AM62P board you can see the below comment, saying in the same PCB footprint you can install either OSPI NOR Flash or (serial) OCTAL NAND. Same hardware interface...

    Regards, Andreas