Working with schematic editor:

Here you will draw the schematic diagram. The components can be found in the library, to the left of the main window:

Connect the elements using Add/Wire  tool.

All the ports going outside the FPGA (inputs and outputs) should use the corresponding buffers: (IBUF = input buffer, OBUF = output buffer), i.e.:

To generate constant value (logic 'zero' or 'one'), use the following button:

To add new ports, the following button can be used:

Add/Wire  draws single wires.

To draw a bus, first draw a wire, then add a bus name to the wire (i.e. data(7:0) ) with Add/Net Name :

- click on

- enter the bus name in the window::

- click on the wire, which will be changed into a bus.

To extract a single wire from the bus, it is enough to give an appropriate name to this wire going out from the bus, i.e. data(4). You can also use the tool Add/Bus Tap .

When the schematic diagram is ready, save it .