The Fitter cannot create sufficient VREF pins during compilation. This message can occur for one of the following reasons:

• Available memory is insufficient to continue running the Fitter.

• The target device is too small to accomodate the number of pins in your design, for example, the number of user-assigned pins prevents the placement of V_REF-dependent pins.

Perform one of the following actions:

• Temporarily close other Windows programs to make enough memory available to run the Quartus II software and do not run other programs in the background. You may be able to free up more memory by exiting from Windows and then restarting Windows and the Quartus II software, and by increasing the size of the Windows swap file on your hard disk. You can also add more memory (RAM) to your computer.

• Change or delete assignments to I/O pins in the device, or select a larger device.