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C6455 EMIF boot mode

Bryan Busacco
Expert 1215 points

COntinued from an earlier discussion on Booting with NOR FLASH on the EMIF.

Per SPRUGK2, page 13. It looks like if we partially boot the 6455 DSP in 8-bit EMIF mode, then re-configure for 32-bit mode to finish the boot process, the tables on page 13 seem to indicate that there is an issue with the "EA" and "BA" pins. It appears that they have different functions when in 8-bit and 32-bit mode. Is there a pin conflict preventing this from working?

 

We like the idea of beginning a boot on EMIF with NOR FLASH in 8-bit mode, then putting the DSP into 32-bit EMIF mode, then finishing the boot. THis only wastes a small portion of FLASH ( from the early boot in 8-bit mode ).

 

Bryan Busacco.

  • 0
    TI__Mastermind 41665 points

    This does appear to be a problem, to make the move from 8 bit boot to 32 bit flash work you would need some external muxing such that the BA signals go to the lower address bits of the flash during boot, but are dropped off when switching to 32 bit mode (as easy as a GPIO toggle). On the positive side the mux does not need to be all that wide, just wide enough to cover the address bits you need to access in 8 bit mode to do the initial boot, a 12 bit wide mux would give you 4kB of initial boot space.