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brunocavagna
Visitor
Visitor
4,070 Views
Registered: ‎04-07-2011

DDR2 MEMORY CONTROLLER - UCF ERROR FROM MIG

Hi all,

 

I generate a DDR2  MEMORY CONTROLLER  with MIG 3.61. During mapping in ISE 12.4, I have a really odd error that I don't understand.

 


ERROR:Place:864 - Incompatible IOB's are locked to the same bank 27
   Conflicting IO Standards are:
   IO Standard 1: Name = SSTL18_II, VREF = NR, VCCO = 1.80, TERM = NONE, DIR =
   OUTPUT, DRIVE_STR = NR
   List of locked IOB's:
       DDR2_DM[0]
       DDR2_DM[1]
       DDR2_ADDR[7]
       DDR2_CKE
       DDR2_ADDR[11]

   IO Standard 2: Name = LVDS_25, VREF = NR, VCCO = 2.50, TERM = NONE, DIR =
   BIDIR, DRIVE_STR = NR
   List of locked IOB's:
       DDR2_DQS_N[0]
       DDR2_DQS_N[1]
       DDR2_DQS_P[0]
       DDR2_DQS_P[1]

   These IO Standards are incompatible due to VCCO mismatch.

 

I understand the error, you cannot have a SSTL18 and a LVDS_25 IO  in a the same IO bank. And I agree!

 

But, have a look to the UCF file with the IO contstaints .The UCF is taken from MIG that has not been modified.

 

NET  "ddr2_dq[*]"                               IOSTANDARD = SSTL18_II_T_DCI;
NET  "ddr2_dqs_p[*]"                            IOSTANDARD = DIFF_SSTL18_II_T_DCI;
NET  "ddr2_dqs_n[*]"                            IOSTANDARD = DIFF_SSTL18_II_T_DCI;


My problem is ddr2_dgs_p/n IOs are defined as a DIFF_SSTL18_II_T_DC and not LVDS_25.

 

Does anyone has an idea about this issue?

 

Thanks,

Bruno


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3 Replies
eteam00
Instructor
Instructor
4,069 Views
Registered: ‎07-21-2009

Your analysis of the problem is absolutely correct.

 

I've never dealt with this problem, so I'm guessing on these suggestions:

  • Try Project > Cleanup Project Files
  • Search for unexpected or extraneous .UCF files in your project folders, and toss (or rename) the dodgy ones.

-- Bob Elkind

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brunocavagna
Visitor
Visitor
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Registered: ‎04-07-2011

I remove unused UCF files and I clean up Project filesas you suggest but the same errors remain.
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mcgett
Xilinx Employee
Xilinx Employee
4,044 Views
Registered: ‎01-03-2008

It appears the UCF file that you are editing is not being used by your ISE project.  Check your report files to see which UCF it is actually reading.

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com
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