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Should the External Memory XINTF on the Memory Map for F28335 32bits instead of 16 bit?

Hainan Wang
Intellectual 450 points

The memory map of F28335 is confusing to me. The External memory XINTF has a 32 bit data bus. However, the memory map for zone0/6/7 is only 16bits. Why is that?

For example, XINTF Zone 6 is 1M x 16 on the memory map, should it be 1M x 32?

Could it be the memory map used here is evolved from F281x memory map and failed to change to 32 bit?

  • 0
    TI__Guru 61235 points

    Hainan,

    The F2833x XINTF can be configured for 16-bit or 32-bit wide data bus.  But that doesn't change the address space.  The C28x address space is in 16-bit words.  For example, address 0x10_0000 is a 16-bit word.  Address 0x10_0000 is the next 16-bit word.  If you did a 32-bit read of address 0x10_0000, you would read the 16-bits from address 0x10_0000 and the 16-bits at address 0x10_0001.  I believe the compiler would have the MSW at 0x10_0001, and the LSW at 0x10_0000.

    So the memory map in the datasheet is correct.  Zone 0 is 4Kx16, Zone 6 is 1Mx16, and Zone 7 is 1Mx16 in size.

    Regards,

    David