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OMAP-L138: mDDR data lines swapping

Vladislav Shmelev
Prodigy 80 points

Part Number: OMAP-L138

Hello! For the OMAP L138, is it fine to swap data bits within a byte of LPDDR (MT46H64M16LFBF)?

Would it work correct?

In my schematic i swapped UDQ bits, but just read that JESD forbidden that.

Thank you!

  • +1
    TI__Guru* 90725 points

    I believe swapping bits within a data byte is allowed.  Can you point me to the location in the spec where it says this is forbidden?  The only caveat with swapping data bits is that when you read MR registers, you would have to translate the read value on the byte with the swapped bits.

    Regards,

    James

  • 0
    Prodigy 80 points

    Hello James, thank you for your answer! It's my mistake i saw it in JESD209-2F (LPDDR2) in Annex B "LPDDR2-NVM Boot Procedure": "NOTE 2 Ordering of DQ bits shall be maintained in the system, including within the package and on the PCB. DQ byte swapping and DQ bit Swapping are not allowed in the system."

    I didn't have JESD209A for LPDDR, hope you are right.

    Thank you.