FlexSPI Boot - which FlexSPI port?

[chriscowdery]

Hi All,

 According to the reference manual for iMXRT1021, table 8-1 (ROM Bootloader Peripheral PinMux), the Bootloader can boot from FlexSPI_A in two places, and FlexSPI_B.

But I cannot see how it decides which one is the correct port?

Does it try all of them until it finds a good one?

I see nothing in the fuses or GPIO pins to control this feature?

Thanks,

Chris.

[victorjimenez]

Hi Chris, 

ROM does not support boot from FLEXSPI_B port directly. ROM always seeks a valid Flash Configuration Block from the FLEXSPI_A port and then re-configures the FLEXSPI controller using the valid parameters in the block read-out. This reconfiguration can include but is not limited to, FLEXSPI_B port support.

Have a great day,

Victor

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[chriscowdery]

Hi Victor,

 Thanks. Does that also mean that the Boot ROM always uses FLEXSPI_A 'primary pinmux' ? I.e. I cannot connect my Flash to the 'secondary pinmux' port (page 186 of Reference Manual) ?

Thanks,

Chris.

[victorjimenez]

Hi Chris,

You can use the secondary pinmux, but keep in mind that these pins are used only for QSPI devices as specified in Table 8-9. Also, if you want to use these pins you will have to burn the corresponding fuses on the BOOT_CFG1 field.

Regards, 

Victor