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66AK2H14: Need more info about DXnGSR2 of Keystone II device DDR register

lding
Guru* 95265 points
Part Number: 66AK2H14

Hi, 

The question opened for my customer: 

We’ve noticed on our boards with TI K2 SOC: Write Bit Deskew Warning and Write Eye Centering Warning bits from DXnGSR2 are set. Can you please give as a bit more explanation, as :

  • What does those warnings really mean?
  • What are the conditions to trigger those warnings?

We already looked at Table 4-66. DATX8 General Status Register 2 (DXnGSR2) Field Descriptions in Keystone II Architecture DDR3 Memory Controller User's Guide. We are looking for more information regarding those warnings. We would like to understand why we see it in our system.

Regards, Eric

  • 0
    TI__Mastermind 28045 points

    We'll check in to this and get back to you in a day or two. 

  • 0 in reply to PaulM
    TI__Mastermind 46460 points

    Eric,

    Per the DDR3 User Guide (SPRUHN7):

    WEWN - Write Eye Centering Warning: Indicates, if set, that the byte lane n has encountered a warning during execution of the write eye centering training.

    WDWN - Write Bit Deskew Warning: Indicates, if set, that the byte lane n has encountered a warning during execution of the write bit deskew training.

    These warnings indicate that the edge of the data eye was not found before encountering the search limit.  This is not indication of a leveling error.  It simply means that the write eye is so large that the range limit was reached before finding the edge of the eye.  Also note that write eye centering and write bit deskew are features of this PHY that are not required for DDR3 operation by JEDEC and are not required by TI to operate at the rated speeds.

    Tom