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DDR4 calibration failed

SYiwe
Novice
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Hi,

I instantiate a EMIF IP core with DDR4 protocol in my design, modify memory timing parameters and board skew values.

The DDR4 speed bin is 2400 and CL=16.

After programming the device in EMIF debug toolkit, I get the following calibration report, and emif_clk_user is correct, measured 267MHz≈1066.667MHz/4, but the local_cal_sucess is low.

The following pictures and txt files are resluts of EMIF debug toolkit. I will be appreciated if anyone can give me some suggestions.

Thanks, regards.

calibration status per gruop.PNG

read data valid windows.PNG

write data valid.PNG

DQ Pin Margins.PNG

DQ pins margins observed during calibration.PNG

VREF margins.PNG

FIFO settings.PNG

controller latency.PNG

 

 

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BoonT_Intel
Moderator
1,952 Views

Hi, I assume this is on your custom board? do you have the RZQ resistor connect on board?

Also, here is the checklist that you can refer to:

https://www.intel.com/content/www/us/en/programmable/support/support-resources/support-centers/devices/cfg-index/calibration-checklist.html

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SYiwe
Novice
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Thank you.

Which of the following should I choose if my DDR4 SDRAMs and FPGA are soldered on the same borad: component, UDIMM, RDIMM or anything else?

Regards.

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BoonT_Intel
Moderator
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Hi,

If solder on board, mean it is not a DIMM device. Thus, choose - component.

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SYiwe
Novice
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where can I found the process of calibration?

thanks, regards.

 

 

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SYiwe
Novice
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Thank you.

I can see three calibration stages in table 45: Address and command, Read, Write.

Does the three stages process as "Address and command" first, then "Read", and "Write" last?

Thanks, regards.

 

 

 

 

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BoonT_Intel
Moderator
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Hi Yes,

Add/Cmd calibration goes first. then follow by read and write.

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SYiwe
Novice
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The calibration failed at "write per-bit deskew" stage, any suggestions?

Thanks.

 

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BoonT_Intel
Moderator
1,952 Views
  • Check the DQ/DQS line length matching. Confirm is the board layout meeting the guideline.
  • Try to reduce the interface frequency and retry. From the screenshot, looks like you are using 1066MhZ? Maybe reduce to 533Mhz.
  • change the data line output and input impedance setting. - on FPGA IO tab.

 

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SYiwe
Novice
1,952 Views

thanks.

In my current design, maximum skew within DQ/DM/DQS is 7.3ps, but both "maximum board skew within address/command bus" and "average delay difference between address/command and CK" exceed ±20 ps, I think that violate the guidelines and results in calibration error, although no errors in "Report DDR".

Is there any way to solve this problem except hardware update?

thanks, regards.

 

 

 

 

 

 

 

 

BoonT_Intel
Moderator
1,952 Views

Hi,

Basically we need to follow the board design guideline to get the calibration pass.

for now, I think you can try to reduce the frequency of the interface.

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BoonT_Intel
Moderator
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Hi, Perhaps you can give it a try by reduce the interface frequency (to 533MHz) and see the calibration results.

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BoonT_Intel
Moderator
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Hi Sorry for late,

I remember I replied to you few days ago but unsure why the note is not sticky.

Basically there is no other way to fix the hardware issue. but I can suggest you give a try on reducing the frequency to half of current interface frequency and see if the calibration pass.

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BoonT_Intel
Moderator
1,952 Views

Hi Sorry for late,

I remember I replied to you few days ago but unsure why the note is not sticky.

Basically there is no other way to fix the hardware issue. but I can suggest you give a try on reducing the frequency to half of current interface frequency and see if the calibration pass.

 

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