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AM3894 EMIF4 register settings

Andrew King
Prodigy 80 points

I have found and used the register settings spreadsheet here. I have  a query over one of the default values though.

All the default values seem to match exactly those found in the Elpida DDR3 datasheet for the part shown on the Sitara Evaluation board with the exception of one field.

The value provided in the spreadsheet for tFAW is 40nS where the datasheet gives 30nS for 8 bit DRAM at 800MHz clock speed. Is there any reason for this discrepancy? The datasheet value for the Micron part I am using is also 30nS, should I also be using 40nS instead?

  • 0
    TI__Guru**** 170625 points

    Hi Andrew,

    Is this the Elpida DDR3 datasheet you are refering to? http://support.spectrumdigital.com/boards/netra/revb/files/E1463E40-DDR.pdf

    I checked the AM389x TRM, and it states that for 8-bit DDR3 memory, tFAW should be 30ns. tFAW is 40ns for 16-bit DDR3. Same as the Elpida datasheet.

    7.6.4.3 Configuring SDRAM Timing Registers (SDRTIM1, SDRTIM2, and SDTIM3)

    The SDRAM timing 1 register (SDRTIM1), SDRAM timing 2 register (SDRTIM2), and SDRAM timing 3 register (SDRTIM3) configure the DDR3 memory controller to meet the data sheet timing parameters of the attached DDR3 device.

    Table 7-30. SDRTIM1 Configuration

    tRRD/tFAW    30 (x8)   40 (x16)

    So, most probably the spreadsheet should be updated. I will double check with the spreadsheet owner and let you know his answer.

    Best regards,

    Pavel

  • 0 in reply to Pavel Botev
    Prodigy 80 points

    Hi Pavel, yes, the datasheet is the same.

    It's not really a big deal, our DDR looks to be working, it's just that the spreadsheet defaults seemed to be modelled on the device used on the Evaluation board scehmatic with the exception of this parameter which made me wonder if your practical experience with the evaluation board led to reconsideration of the ideal value to use.

    Thanks for spending time looking into this, I'l be interested to see if the spreadsheet owner has any comment.

    Cheers

    Andy