0.1 A quartus project from start to finish: 2 bit mux tutorial  (Page 2/4)

• After this you will have to specify your target FPGA. The FPGA in the DE0 board we will be using is a Cyclone III EP3C16F484C6 . You can also find this information by looking at the specification printed on the chip itself.

• The next screen allows you to specify other programs to use with this project in addition to Quartus. We won’t be using any of these so just click next. After reviewing everything on the final screen to make sure it’s set up as you want it and you’re ready to begin laying out your circuit.

Building a circuit in quartus

• Although we specified a name for our top level design file, we still need to create it. Go to File->New or hit Ctrl+N and select Block Diagram/Schematic File under Design Files. Once it’s open go ahead and Save As, Quartus should automatically give it the same title as the project. Make sure that the box titled “Add file to current project” is checked before saving and that the file is being saved into the project folder.

• You should now see a grid of dots and just at the top of it a toolbar. This is where most of our work in Quartus will take place.

• In the upper left corner of the window is the project navigator. Since we only have one file in our project, there’s not much to see here, but if we had more we would be able to easily keep track of the hierarchy of all the files within the project. Additionally, we can easily open up files associated with this project by double clicking them within this box.
• We’ll start by adding symbols to our schematic. Normally you would want to first plan out your circuit design by using Karnaugh maps to write logical functions for the operation of your circuit, however, we’ll proceed as though this step has already been completed.
• Click on the place symbol tool to open up the library of available symbols. This can include the default symbols included with Quartus as well as any user created symbols. Within the Quartus library, the majority of the symbols we’ll be using will come from the “primitives” folder. Start by finding a two input AND gate. You can either navigate to the “logic” folder under primitives and find the gate labeled “and2” or simply search for this symbol using the name box below the browser. Note that the name typed here has to exactly match the symbol name for Quartus to find it. Before you click okay, make sure that the box labeled repeat-insert mode is checked as shown below.

• Place two AND gates onto the grid. Although their relative position isn’t that important since we can remotely connect symbols, it always helps to have a neat circuit layout so for now place them relatively close together. Once you’re done, hit escape to exit from placement mode.
• Continuing on, go back to the symbol browser and select an “or2” gate, also located in primitives->logic. Place one of these gates to the right of your two AND gates.
• Next we’ll add an inverter to implement the select logic for the MUX. In the symbol browser find the “not” gate. Place this close to the input of one of the AND gates. Note that it shouldn’t be a problem at this point, but if you ever find yourself running out of room on the grid, drag a component to the edge of the screen to expand the available area.
• Now we’ll add in I/O pins. This is where signals will enter and leave the schematic. They can be connected to other schematics in the project or connected to inputs and outputs on the board, though we’ll define these connections later. For now, go to the drop-down menu on the Pin Tool and choose input. Again, you can place your pins anywhere due to remote wiring, but for now, place two pins to the left of your logic gates for the inputs to the MUX and one above them for the select signal. Go back to the symbol tool, select output, and place one output pin to the right of your circuit for the output of the MUX. Right click on your I/O pins and select properties. From here give each pin a representative name, which will help out in the later I/O assignment phase.