You may see the following compilation errors in the Quartus® II software, if you make pin assignments to your dedicated GXB pins without instantiating and fully connecting the ALTGXB megafunction in your design:
Error: Can't place input pin <pin name> in <pin location> because the pin is not connected to GXB Transceiver logic but the location is GXB Receiver pin.
Error: Cannot place I/O <pin name> in <pin location> because the I/O is not connected to GXB transmitter.
To avoid these errors, follow these steps:
- Instantiate the ALTGXB megafunction in your design.
- Ensure that all megafunction ports are fully connected.
- Apply the Virtual Pin assignment to any internal or core-side signals that should not connect to device I/O pins.