Error CMP411: DDR instance <instance name> must be connected to an I/O cell.

The DDR cores – DDR_REG and DDR_OUT - are intended to be paired with a regular I/O core to use the built-in DDR I/O functions.

Action

If you need the DDR functionality on a net not connected to a regular I/O core, use regular gates to build the DDR functionality. This may affect your design performance and area usage; Actel does not recommend it.