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VC5505 bootloader and asynchronous NOR flash

Chongding Zhao
Prodigy 110 points

Hi

When VC5505 boot from EMIF using a NOR flash, it doesn't specify the exact address of boot table and, instead, it search all 4 external interfaces until it finds the valid boot signature. My question is how the boot loader identify if a NOR flash has a bottom or top boot block? Does the bootloader try both options?

Thanks for help,

Qing

  • 0
    TI__Mastermind 30120 points

    Hi Qing,

     

    When the bootloader reads from NOR flash, it starts reading from address 0x0000 regardless of bottom/top/uniform parameter block configurations. If a valid boot signature is located in 0x0000, then the bootloader copies the boot image to memory and begins executing from memory.

     

    Special care only needs to be taken if you are reauthoring the NOR flash, which requires re-writing the NOR flash. In this case, the number of sectors and the sector size of each erase block must be known prior to writing to the NOR flash. This erase block information can be obtained through the CFI Query or by looking up the Manufacturer ID/Device ID in a table of explicitly supported devices.

     

    For more information, see Section 2.2.1 of the Bootloader App Note (http://www.ti.com/litv/pdf/sprab92).

     

    Are you experiencing a problem booting from NOR Flash?

     

    Hope this helps,

    Mark