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AM2631: 4 MB address space (addressable) according to Table 5-1 in DS vs. TRM in section 13.3.1.2.1 GPMC Modes

Chris Yorkey
Genius 15855 points
Part Number: AM2631

TI SItara MCU Friends & Family!

We have a small discrepancy with Target device AM263x.

Customer desires 16-32MB SDRAM (synchronous DRAM) externally.

GPMC interface on AM263x appears to support only 4 MB address space (addressable) according to Table 5-1 in DS.

So, it begs the question how could a potential Sitara MCU+ customer use 32MB external DRAM in their system ?

General-Purpose Memory Controller (GPMC) module on AM263x.

AM263x supports 8- or 16- or 32-bit-wide path to external memory devices.

AM263x supports up to 4 independent chip-select regions of programmable size and programmable base addresses on 16MB, 32MB, 64MB, or 128MB boundary in a total address space of 128MB.

 TRM in section 13.3.1.2.1 GPMC Modes that illustrates this further.

We believe this could be a suitable option for interfacing to 32MB external RAM.

So IS there a discrepancy between the DS and TRM - or is this simply user error misunderstanding and perhaps could it simply be made more clear?

Thank you,
Chris

  • 0
    TI__Genius 15855 points

    Team,

    Just to clarify.  External DRAM support isn't really the question here (sorry if I didn't make that clear).

    That (DRAM) may be a legacy support question.  This is more of a fundamental I/F question and addressable capability. 

    More importantly, that the GPMC supports Flash, NOR and NAND type, but also SRAM and PSRAM.

    Comments indeed welcomed.

    -Chris

  • +1 in reply to Chris Yorkey
    TI__Guru 55025 points

    Hi Chris,

    Both data sheet and TRM are correct.

    In DS, it focused on the Address and Data usage in non-multiplexed mode. Since it is only has 22 bit address, so the addressable space is 4MB.

    In TRM, the GPMC can be used in A/D in multiplexed mode. Please see the detailed description in "13.3.1.2.1 GPMC Modes" of TRM.

    Best regards,

    Ming 

  • 0 in reply to Ming Wei
    TI__Genius 15855 points

    Hi Ming,

    Thank you!  Though, this might not be that obvious to an end customer (ours was confused) and honestly even I needed clarification.

    Perhaps at/during the next Rev of the DS it can simply be reworded to reflect your statement, which to be honest would be very helpful.

    Thank you,

    Chris