Forum Discussion

MPerg's avatar
MPerg
Icon for New Contributor rankNew Contributor
7 years ago

Report DDR timing report - negative slack meaning

Hello,

I'm using Arria10 FPGA with 2 DDR controllers:

One is connected to HPS and the other is connected to FPGA logic.

When I run TimeQuest analysis I get under report DDR report negative slack on "Memory calibration" line under two reports:

1. DQS gating

2. Write Leveling

Attached screenshots and report DDR report.

I would like to be sure it's OK before we get this board to production.

What is the meaning of the slack?

1 Reply

  • BoonT_Intel's avatar
    BoonT_Intel
    Icon for Frequent Contributor rankFrequent Contributor
    7 years ago

    Hi Sir,

    The negative value on the "memory calibration" is expected and ok as long as the final (sum up) value is positive (last row) - for your first screenshot, it is "Final write leveling margin".

    In conclusion, the timing is ok as long as you do not receive critical warning said "DDR timing not met" in quartus timing report.

    Hope this helps😃