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IMX7D, LPDDR3 register setting Query

Question asked by Logesh S on Jan 10, 2018
Latest reply on Jan 10, 2018 by igorpadykov

Hi,

 

We are using IMX7D (MCIMX7D3EVK10SD) in our board along with Kingston LPDDR3 (08EMCP08-EL3DT227-A01U). I'm filling out the (MX7D_LPDDR3_register_programming_aid_v1_4) Register Programming sheet. I have downloaded the Excel sheet in below link,

 

i.MX7D DRAM Register Programming Aid 

 

I have below query in DDRC_ODTCFG register,

 

1. In downloaded Excel sheet, under register configuration sheet, line item 158 is as below,

WR_ODT_HOLD1.25606000000Note, for LPDDR3, input the value of tDQSS from the DRAM data sheet (in clock cycles), otherwise for DDR3, this will be automatically set to 0x6.
Description: Cycles to hold ODT for a write command. The minimum supported value is 2.
For DDR3:
■ BL8 - 0x6
■ BL4 - 0x4
For LPDDR3:
RU(tDQSSmax/tCK) + 4
Value After Reset: 0x4

 

 

My Query is in line item 158 under LPDDR3 they have mentioned a formula "RU(tDQSSmax/tCK)+4" but in Cell D158 the formula does not use tCK value (=IF(C17="DDR3", 6, ROUNDUP((C158 + 4),0))). Where the formula supposed to be (=IF(C17="DDR3", 6, ROUNDUP((C158/C31 + 4),0))).

 

Please confirm what value should i use in cell C158 while programming. Should i want to use the value of tDQSS (1.25ns) alone (Resulting Value = 6) or should i want to use correct formula in C158, RU(tDQSS/tCK) which will be "1" (Resulting Value = 5)?

 

Kindly Confirm.

 

Thanks,

Logesh

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