Hierarchical Design

[wangqueping]

hi,all:

 When I using mcb connect to DDR2 in my design ,there is errors occur at map process.the error log is following:

ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=L1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=M1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=L3) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=M2) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=N1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=N3) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=P1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=P2) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=R1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=R3) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=T1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=T2) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=U1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=V1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=U3) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=V2) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=W1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=W3) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=Y1) which requires the combination of the symbols listed
   below to be packed into a single IOB component.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
   constraints (LOC=Y2) which requires the combination of the symbols listed
   below to be packed into a single IOB component.

all these pins are the mcb's pin and connect to mcb's pin relatively.However the map tool report these errors.

Anyone can tell why these error ocuurs.And how can i do to solute the problem?

thanks all.

[gszakacs]

The error messages you posted are incomplete.  If these were copied from the errors tab in the ISE Navigator,

you should instead open the Map report to see the full error including the description of "the symbols listed below,"

which don't show up in the message you posted.  Then maybe it will shed some light on the issue.

-- Gabor

[chenweit]

Queping,

The map errors provide you a clue to look at where the potential problems may be. If your PR region has the DDR IP that already instantiated IOBUF, in your top level code, remember to instruct Synthesis tool to not auto insert additional IBUF/OBUF for these signals. Check the LOC constraints or print out full map reports with details to see what these signals are.

It could also be possible that these signals requires differential driver. In that case, please code accordingly. You can use planahead to investigate furthe or open a Xilinx tech support case. 

Regards,

Wei