MIG (Memory Interface Generator)

[gerard.visser]

Hello,

  Regarding the Spartan 6 MIG, on page 24 of ug388 there are just a few cryptic words about reserved address space:

"C_MC_CALIBRATION_RA
C_MC_CALIBRATION_BA
C_MC_CALIBRATION_CA
Defines the starting row, bank, and column
address reserved for calibration. This attribute is
used for training pattern data during
recalibration to avoid overwrite of application
data."

 I presume the implication is that the memory content at some addresses will be overwritten/corrupted by the DQS phase calibration? Is it really so? And if so:

 Could someone briefly explain how large is this reserved address space? Odd that it isn't stated in ug388...

 And further, is there a way to turn off the "continuous DQS calibration" while still using the initial DQS calibration? That would presumably avoid the need to reserve any address space for it. In our application temperature and supply voltages will be pretty constant and I suspect we don't need the continuous calibration...

  I must point out, I am currently using ISE 12.2 for initial stages of a new design, I know this is out of date and will update soon. I apologize in advance if the answer to my question would be obvious after updating and looking at the new MIG output.

  A little expert advice on this will be appreciated, thanks,

    Gerard

[bethf · Accepted solution]

The calibration address is at location 0 in the memory space and is only used during the initial start-up calibration upon reset where the SDRAM does not contain user data.  During continuous DQS Tuning, the MCB simply looks at the incoming DQS and makes adjustments as necessary.  There are no additional commands sent to complete the continuous tuning.

[gerard.visser]

Thank you for clarifying this.

So, user data is safe at any location in the memory without restrictions. I hope that I am interpreting your response correctly in saying so. (Please correct if not).

This takes care of the issue for me. Again, thank you...