Description
One reason this can happen is because the unused pins in the FPGA design are not tri-stated. Make sure you have the unused pins for your Quartus II project set to be Inputs Tristated. You can do this as follows in the Quartus II tool:
- Click on Assignments -> Device
- Click on the Device and Pin Options button
- Click on the Unused Pins tab.
- Click on the As inputs, tri-stated radio button