Recommendations for write leveling delay values on i.MX6Q

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Recommendations for write leveling delay values on i.MX6Q

Jump to solution
798 Views
jschoen
Contributor III

Should the WRITE_LEVELING delay register values be set greater than the worst case delay value measured across boards?

The documents and discussions usually defer to using a model of the design to set the WRITE_LEVELING delay, but from our measurements using the DDR Stress Test, there is significant deviation board to board which may not align with a modeled design center.  Proposing to set delays in the shape of the average line but offset to where they are beyond the worst case delays

Labels (1)
0 Kudos
1 Solution
623 Views
igorpadykov
NXP Employee
NXP Employee

Hi jschoen

procedure normally to average them

Best regards

igor

View solution in original post

0 Kudos
3 Replies
623 Views
igorpadykov
NXP Employee
NXP Employee

Hi jschoen

I am afraid it is not true to use worst case delay value measured

across boards. Ideally board should use own  WRITE_LEVELING delay register values.

Difference accross boards may be caused by impedance mismatch or board noise.

One can recheck with sect.3.4 DDR routing rules IMX6DQ6SDLHDG

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------

0 Kudos
623 Views
jschoen
Contributor III

Igor,

I found this related post : https://community.freescale.com/thread/319387

It suggests sampling 5-10 boards and get calibration values.  Then balance the write leveling values (normally average them).  This is essentially what we've done....obtained calibration values for a sample build of same board design.

Is it recommended to average the write leveling value or use the worst case delay value?

Thanks.

Joel

0 Kudos
624 Views
igorpadykov
NXP Employee
NXP Employee

Hi jschoen

procedure normally to average them

Best regards

igor

0 Kudos