ID:21610 Output port "<name>" in <name> entity "<name>" does not have a driver. Connecting to the default value "<value>".
CAUSE: The given output port is not connected to a driver in the RTL. However, the port is used in the instantiating entity, or is a top-level output port. It will automatically be connected to the given default value.
ACTION: Connect the output port to an RTL driver if this behavior is not intended.