Keyword: Spartan-II, Virtex-E, I/O Standard, 993
The following error messages are reported:
"ERROR:Place:1827 - There are special SelectI/O banking requirements for the package being targeted. Please refer to the SelectIO application note. The IOBs in your design cannot be automatically placed. Xilinx recommends that you lock your IOBs to specific sites."
"ERROR:Place:993 - Due to Virtex SelectIO banking constraints, the IOBs in your design cannot be automatically placed."
A current limitation exists for the placer when it deals with designs that:
- Contain SelectIO standards with more than one VCCO requirement, and
- Use packages that have fewer than eight VCCO banks.
The placer cannot automatically place these IOBs. Therefore, it is necessary for the user to apply placement constraints to the affected components. If these constraints are not applied, the messages above are reported.
The following architectures and packages are affected by this issue:
Virtex: TQ, PQ, HQ, CS
Spartan-II: CS, TQ, VQ, PQ
More details are available in the Output Drive Source section of the following Xilinx Application Notes:
To work around this problem, manually place a LOC constraint on each I/O to a specific pin in order to meet the SelectIO requirements.