The design is targeted to device sp3400-tw144-4.
I create the design in the PlanAhead tool and assign a LVDS differential port to site P77 and P78.
The following error occurs during implementation:
[Constraints 5] Cannot loc terminal 'lvds_p' at site P77, Site PAD124 is not part of a diff pair ["C:\my_proj\project_3\project_3.runs\impl_1_2\.constrs\lvds_error.ucf":5]
[Constraints 5] Cannot loc terminal 'lvds_n' at site P78, Site PAD123 is not part of a diff pair ["C:\my_proj\project_3\project_3.runs\impl_1_2\.constrs\lvds_error.ucf":7]
Why does this error occur?
The sites P77 and P78 are differential ports. However, the PlanAhead tool does not show them as a differential pair and is unable to comply with the constraints.
To work around this issue, implement the design in Project Navigator or use the ISE command line tools.