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EMIF16 256MB NAND Flash and 16MB NOR Flash

Wenjun Huang
Expert 1770 points

Why is the EMIF16 able to support For Up To 256MB NAND Flash and 16MB NOR Flash?

It should be either 256MB NAND Flash or 16MB NOR Flash?

  • 0
    Expert 1120 points

    Huang

    The interfaces are different between NAND and NOR Flashes.

    Though one CE space of the EMIF16 is 64M,  the EMIF16 only supports 16MB NOR Flash because there are 24 address lines. However, the addressing of a NAND Flash does not depend on the address lines, so the memory capacity can be different. You may want to google 'NAND vs. NOR' for further information.

    Han

  • 0 in reply to haopeng han
    Expert 1770 points

    Han

    EMIF16 has 64MB per CE, implying that 1 CE has 64 *2^20 number of bytes (equivalent to 26 address line) due to the presence of EMIFBE1 (upper byte) and EMIFEB0 (lower byte) and the 24 address lines.

    16MB NOR Flash => 16M (equivalent of 24 address line) of words since this is only considering the 24 address lines and not the EMIFBE1 and EMIFBE0?

    I realise that the NAND flash does not need address line to address the memory, unlike the NOR flash but not so sure why is that so? Any website to recommend?

  • 0 in reply to Wenjun Huang
    Expert 1770 points

    Another question is does c6672 support either 16MB NOR flash or 256MB NAND flash or both concurrently?

  • 0 in reply to Wenjun Huang
    Expert 1120 points

    Oops, it's 16M not 16MB. 24 address lines can address 16M positions. And yes, EMIF16 on the Keystone devices can support both NAND and NOR flashes. Be care if you want to boot from the NOR flash since it can only boot from 0x70000000.

  • 0 in reply to haopeng han
    Expert 1770 points

    From the C6672 datasheet,

    Start            End            Bytes Description

    70000000 73FFFFFF 64M EMIF16 CS2 Data NAND Memory

    74000000 77FFFFFF 64M EMIF16 CS3 Data NAND Memory

    78000000 7BFFFFFF 64M EMIF16 CS4 Data NOR Memory

    7C000000 7FFFFFFF 64M EMIF16 CS5 Data SRAM Memory

    Is it that the NOR flash can only use 7800 0000 to 7BFF FFFF, hence it can access 16 M of addresses (which is 64 MB)

    But NAND flash can access from 7000 0000 to 7FFF FFFF, hence it can access 256 MB of addresses.

    However, it is not possible to have a system with both 256 MB NAND flash and 64 MB NOR flash, but it is possible to have 128 MB NAND flash and 64 MB NOR flash.

  • 0 in reply to Wenjun Huang
    TI__Mastermind 30825 points

    Wenjun,

    Yes, what you're suggesting is correct. You can support all CS spaces w/ their various memory options.  SRAM and NOR Flash are limited to CS4 and CS5 respectfully, NAND can be on all four of the CS's. 

    Best Regards,

    Chad