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AM335x DDR2 timing : Calculation tool vs EVM board

Other Parts Discussed in Thread: AM3359

Hi,

In order to understand how to configure SDRAM_TIM_1, SDRAM_TIM2 and SDRAM_TIM3, I've compared the values given by the DDR Calculation tool with the values defined in the U-boot of the TI AM3359 EVM board.
Some values are the same, some others are fast the same and some others are totally differents.
 
Which values are the right ones ? Is there some margin to consider on timings ?
And finally how do I have to define register value for the model of DDR2 that I will use in my design and that is not exactlly the same as on EVM board ?
 
Parameters that are not the same in calculator than on EVM board are :
 
name                          calculator                             EVM
 
reg_t_ras                    10                                        11
reg_t_rc                      14                                        15
reg_t_rrd                     1                                          2
reg_t_wtr                     1                                          6
 
reg_t_xsnr                   54                                        59
reg_t_rtp                      1                                         3
reg_t_rfc                      51                                       52
reg_t_ras_max            15                                        7
 
Thanks
Cyril
  • Cyril, the values generated by the calculator spreadsheet are optimal values based on the DDR2 datasheet for the EVM.  The u-boot settings may not be optimal, but you should be able to change u-boot to the calculated values.  If you are going to use a different DDR2, simply substitute the values from your DDR2 datasheet into the spreadsheet to obtain the new optimum values.

    Regards,

    James

  • Hi James,
     
    Thank you for your answer.
     
    I will try to replace the values in U-boot by the optimal ones and test them on EVM.

    Regards,

    Cyril